# Maha MH C808M Charger



## SilverFox

Maha has stepped up to the high capacity charging challenge by offering a new charger in their line up. The C808M is capable of charging AAA, AA, C, and D cells. It defaults to charging at 2 amps, so it does not take an extended period of time to charge up high capacity cells. My 9000 mAh D cells use to take around 36 hours to charge on my Vanson Speedy Box. Using the C808M, it only takes around 6 hours. That is a vast improvement.

This charger has 8 independent charging bays and charges AAA, AA, C, and D NiMh or NiCd cells. You can mix and match to your hearts content, but once the charge rate or conditioning cycles is set, it is set for all 8 bays. You can not be conditioning cells in bays 1 and 2, then set it up to charge cells in the other bays. The choices are: 
1. default charging (0.7 amps for AAA cells and 2.0 amps for AA, C, and D cells), 
2. soft charging at half the default charging rate, or 
3. conditioning. 
The conditioning cycle first charges the cells (at either the default rate or the soft rate), then discharges them at 0.25 amps EDIT It seems I was a bit off on this, it is more like 350 mA but see post #54 for the real numbers END EDIT, then charges them back up again. At the end of the charging cycles, a trickle charge of 0.007 amps keeps the cells ready to go. This low trickle charge rate may make this the only charger that you can leave your cells in for an extended period of time without harm. I do not recommend leaving batteries on trickle charge, but if you want to do that, this is the charger for you.

The C808M comes with a 3 year warranty from Maha.

The C808M does not use springs in its contact set up. It has individual contacts for each size of battery. This makes for a very robust set up, and allows some spacing between cells to keep them cool. The trade off is that the unit has some size to it. The dimensions of the charger unit are EDIT Oops 7.5” x 3.5” x 1.75” is for the C801D the C808M is 12.63" x 5.25" x 3". END EDIT In addition it is powered by an AC switching adapter that is 5.125” x 2.25” x 1.185”. The power supply input is rated at 100-240 volts 50-60 hertz, so it will work worldwide. It uses a maximum of 1200 mA. Mine came with a North American 2 prong blade plug, but you can get power cords to match the outlet style where you are. The power supply uses a DIN plug to connect to the charger. There is no 12 volt DC power provision.

The back lit LCD display shows a graphic of what is going on in each slot and also displays the English words Condition, Charge, and when the charge is completed, the word Done is displayed for each slot. When an error occurs, the word Done will be flashing in the slot where the error occurred. The graphic is the outline of a battery with three bars in it. During discharging, the outline disappears and the bars change from three, to two, to one, then none at all. When charging starts, the outline comes back on. The charging progress is displayed by the three bars until “Done” indicates the beginning of the trickle charge.

A very soft “click” can be heard as the unit charges. This is a result of the pulse charging used while charging, and also while on trickle charge.

You have to pay attention when inserting the cells for charging. The negative end goes in first and then you press down to snap the positive end in place. AAA cells are placed in the bottom and to the right. I had some initial difficulty getting them in the right place, but when I looked at what I was doing, there were no more difficulties. I have noticed that I often don’t get the AA cells completely snapped into place. The display is very good at letting you know that the cell is not in place, because there will be no graphic display.

The right side of the unit gets warm during discharge, and you are instructed to insert cells starting from the left side. I asked Maha about this, and they said it was simply to keep the cells cooler. You are also instructed to put the larger cells on the left side and work your way right with smaller cells. Once again Maha says that they are trying to keep the heat down.

The operators manual also states that you should not leave an empty slot when putting your cells in for charging. Maha does not know why that statement is in there… Anticipating some problems, I did a number of tests starting from right to left, filling the middle slots, and skipping every other slot. The C808M took it all in stride and performed flawlessly. It truly is an independent 8 channel charger – with no restrictions.

I did have some problems charging NiCd AA cells. It seems that they end up at a higher voltage than the C808M thinks they should and I ended up with an error signal. I also tried to charge some Alkaline AA cells and got the same error signal. I talked with Maha about this. They indicated that the charging algorithm was designed for NiMh chemistry, and it should work well with NiCd chemistry as well, but I was finding a bit of a difference. The cells did end up fully charged, they just ended on an error signal and the trickle charge was terminated.

So, if you are charging NiCd cells, you may run into this same thing. Please note that this did not occur with every cycle. Sometimes everything came out fine, but other times I would get the error signal.

The cells come off the charger warm. The highest temperature I observed was 96 F. Maha claims the high temperature cut off is set at 120 F. The charging is consistent from bay to bay. 

I am used to cells coming off the charger at around 1.45 volts. My cells came off the C808M at 1.43 volts. This charger is right there at the top of the pack as far as complete charging goes. The AccuManager 20 just barely beat it out, and it does slightly better than the BC-900. It also just barely beats the Vanson Speedy Box after the charge has completed and the cells have trickle charged for an additional 24 hours.

I am very pleased with the C808M. It will take very good care of your cells during charging and won’t cook them during trickle charging. It also does a very good job of packing a lot of capacity into your cells.

The only error I noticed was while charging NiCd cells, and when I tried to “trick” it into charging Alkaline cells. I believe the NiCd error was because the voltage went higher than expected.

I can give this charger a big “thumbs up” and highly recommend it.

Tom

Edit: I forgot to mention that this charger does not have a on/off switch. The LCD display comes to life when you put a cell in to charge, and goes off when you remove all the cells.

I received an eMail from William at Maha Energy. He explained that the flashing Done that I am seeing while charging NiCd cells is not an error. It is just indicating that the charge was terminated on high voltage rather than delta voltage. He is considering revising the operators manual to include this information.

By the way, William is the one that sent me the charger to check out. Thanks William!!! If you have any questions, William is the one that programed the charging algorithm used by this charger. He has been most helpful in helping me understand how this charger works. If you have questions, let me know, or get in touch with William directly at www.mahaenergy.com .

Another Edit:

Some people have noticed that the 808 will flash "Done" when charging NiCd cells. This interrupts the conditioning cycle and makes that cycle useless for NiCd cells. This is unfortunate because NiCd cells need to be conditioned more often than NiMh cells do.

This does not happen with every NiCd cell, but it appears that the 808 will terminate the charge when the voltage reaches 1.6 volts. This keeps people from trying to charge alkaline cells. Some NiCd cells bump against this 1.6 volt cut off, resulting in the flashing "Done" and ending the cycle.

William was kind enough to reveal a work around for this. You put 1 NiMh cell in slot 1 and select conditioning. When the cell enters the discharge phase, you load up the other slots with your NiCd cells. Once the unit has entered the discharge phase, it does not try to charge the additional cells before discharging them. The results will be a conditioned NiCd cell. You may end up with a flashing "Done" at the end of the charge cycle, but the cell will have gone through the discharge cycle and should be conditioned.

I must add that I have been using this charger for several months now and still am very pleased with it.


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## Tweek

Sounds like I might need another charger... :naughty: 

Did a quick search and it can be purchased from several places:

Thomas Distributing for $99.97 (I like these guys, been buying stuff from them for years)

Eastgear $96.36 (Never heard of them before, found with Google)

Direct from Maha $109.95 (Do you really want to pay full MSRP?  )


Chris


EDIT: Fixed my spelling!


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## jdriller

I was thinking the same thing.


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## BentHeadTX

Finally!
A charger that can handle all 8 of my nFlex WX1S LuxeonV 8AA Mag mod! Although I shy away from charging AA cells at 2 amps, the soft charge 1 amp option should work fine on my Sanyo Industrial 1700mAH NiMH AA cells. The only option I wish for is for it to display the capacity after conditioning the cells. Always nice to know if one of the cells is getting weak taking the packs performance down.
My BC-900 won't condition on one of the bays and it is a PIA to get the damned thing to conditon (what crackhead designed the human interface!?) Luckily, we have our new Cadex $3,700 NiCad, NiMH, Lead Acid, AGM, Lithium-Ion, Lithium-Polymer and primary lithium cell (3 minute test tells the condition of primary lithium cells for defibrillators... top that!) 
Maybe Maha will come out with one that displays the capacity of the cells one day....


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## SilverFox

Update:

William of MahaEnergy told me that the flashing Done that I am seeing at the end of the charge while charging NiCd cells is not an error message. It simply means that the charge was terminated on high voltage, rather than on delta voltage.

I also added some information about the lack of an on/off switch in the first post.

Tom


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## BVH

Tom, thank you very, very much for the thousands of hours (probably more) that you have spent on battery, battery technology and battery chargers research and the resultant knowledge passed along to all of us. Whenever I see a new thread that you've started, I get a jolt of excitement and click on it immediately! I love to read your posts! thank you, Thank You, THANK YOU!!

Mine arrived last week and its worked exactly as you describe. I, too didn't realize until the 2rd batch of batteries that I had not snapped the AA's fully into place. They'll charge without being fully in-place. My only very slightly negative observation is that the vertical viewing angle of the display is a little lower than I'd like. If you view the display at 45 degrees or above, the icons "gray out" a bit. So if you stand over it, the icons will be faint. If you view it from in-front and low, they are "bright".


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## SilverFox

Hello BVH,

Excellent observation. I had the charger on a shelf and did not notice that at all.

Thanks.

Tom


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## BentHeadTX

Thanks Tom,
I will probably pick up the C808M after what I have been reading about the LaCrosse BC-900 charger/conditioner. Don't like the idea of flaming batteries, melted buttons and it's ability to start things on fire. I can use the BC-900 for measured conditioning only at higher 700mA charge rates but need an 8-bay for general charging. 
Accucharger 4 bay at home and C808M 8-bay at work or travel (were I keep my 8AA Mag) Rather large charger but worth it when charging 8 batteries or dealing with different voltages in different countries.


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## Sway

Thanks for the thorough review Tom :thumbsup:

Later
Kelly


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## Bullzeyebill

It would be nice if Maha could speed up that discharge rate in conditioning cycle. 9 amp cells would take mucho hours to discharge at 250mA's. A nice compromise might be 1amp.

Bill


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## bc5000

The MH C801D looks good to me. $30 cheaper than the 808. Looks like the only difference is it only charges AA/AAA. Don't know how long their Holiday Special will go on though.


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## atm

Many thanks for the review Tom, and for all the information you provide here on CPF!

I recently decided to go with rechargeables and started researching the best charger and cells for the job. I can't tell you how valuable the information you have provided is to me, and with a depth of knowledge and experience I could never hope to match!

One Maha MH C808M Charger is on it's way...  

Thanks again for the priceless service you (and CPF!) provide!

Andrew


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## Ben H

Thanks for the review Tom. This is the charger I have been looking for. I've ordered one and can't wait to get it.


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## john2551

Tom,

Is this charger is better than the Ansmann Energy-16? If so, why? I'd like to know the technical stuff!

Thanks,

John


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## Ben H

I got my charger Saturday. I love it. It is so nice to have 8 independent charging bays. I like the charging status display. I wish it could test for battery capacity, but you can't have it all.


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## TooManyGizmos

bc5000 said:


> The MH C801D looks good to me. $30 cheaper than the 808. Looks like the only difference is it only charges AA/AAA. Don't know how long their Holiday Special will go on though.



I agree with bc5000 :
I've had my C801D for a month now. Since the 808 also charges C & D batt's , I assumed it would also have to be a little larger in size to accomidate them. I'm glad they make the 801D at a -$30 reduction for us who only use AA/AAA. 

One thing that appealed to me was the very low current ' trickle charge ' which wont 'cook' the batt's. Thus allowing me to leave 4 aa & 4 aaa's in there ready for use. Also nice is the ability to select the 'soft charge mode' which should increase batt life and charge them closer to maximum capacity b-4 shut-off.

A CAUTIONARY REMINDER : As stated in the 1st paragraph of the instructions. DO NOT use the (default) one-hour rapid charge mode on AA batteries rated UNDER 2000mAh and AAA batteries UNDER 700mAh. To charge them,use the 'soft-charging mode', which means press the soft-charge 'button' after you insert the 1st battery into the far left slot. ( If you put a single battery in the charger that's rated less than 2000mAh it will be getting "Fast charged" @ a rate of 2.0A which is too much current.........unless you press the "soft-charge" button to change the charge " mode " just after putting the batt. in ) .......o.k. ?

I mention this , as many of us are still using 1200,1400 and 1800mAh NI-MH batt's and even some lower mAh NICAD's. It is SO easy to forget and pop-in a less than 2000mAh batt and walk away. The charger will be charging a lower mAh batt at 2.0A (aa) or 0.7A (aaa) which is higher than the overall rating of the battery itself. This I believe might be a fire and melt-down hazard which we are all more cautious of since the latest LaCrosse 900 issues. Over-all I am pleased with my 801D and recomend it with only these 3 minor complaints :

1: As pointed out by BVH to SilverFox on the C808M model (which it appears is similar to the C801D ) the verticle viewing angle of the LCD display makes it hard to read without getting down to it's level .

2: The LCD display has tiny lettering and is hard for me to read - even with reading glasses .

3: It is very hard and annoying to get the batt's back out of the slots without prying them out from the + end with some type of sharp tool - which over time chews-up and damages the covering label of the batt. at the + end and may cause it to tear and start coming off. I dont like it when my batteries loose their descriptive label.Do you? However even I don't have a re-design suggestion to make removal easier.

Other than that..... The C801D seems to be a great charger just like the C808M of SilverFox's report.

Many thanks to SilverFox for his analysis work. I'm sure it's appreciated by all of us.



^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Edited 1/17/2006 by TooManyGizmos to add an update.

Batteries are too hard to remove from the 801 model , so I'm returning mine to exchange for the 808 model which might be more "user-friendly" . ? ?


************************************

We cant have.........TooManyGizmos:naughty:


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## Ben H

How risky is it to charge a cell over a 1C rate with this charger? The Energizer 15min charger charges well over 1 C. It seems highly probable that people (such as myself)will forget to soft charge batteries of lower capacities. Maybe that's why they call it a professional charger......dangerous in the hands of amateurs. :naughty:


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## D MacAlpine

TooManyGizmos said:


> 3: It is very hard and annoying to get the batt's back out of the slots without prying them out from the + end with some type of sharp tool - which over time chews-up and damages the covering label of the batt. at the + end and may cause it to tear and start coming off. I dont like it when my batteries loose their descriptive label.Do you? However even I don't have a re-design suggestion to make removal easier.


 
How about a length of ribbon/tape laid across the bays (under the cells) and fixed at one end. You just need to lift the other end to pop the cells out.
I've seen this in the battery compartments of a few devices and it seems to do the trick.

Don


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## TooManyGizmos

D MacAlpine said:


> How about a length of ribbon/tape laid across the bays (under the cells) and fixed at one end. You just need to lift the other end to pop the cells out.
> I've seen this in the battery compartments of a few devices and it seems to do the trick.
> 
> Don



Concerning the MaHa MH C801D (AA&AAA only charger)....
Thank you Don , that works very well to remove all the cells at one time , but when charging 8 cells of varying discharge status , they all get done charging at varied times. All the cells are so close together that they almost touch each other . When you want to remove a cell thats done charging somewhere in the middle of the 8 , there in lies the difficulty.

Keep in mind , while I try to explain this , that when the battery is fully inserted, the negative 'springy' terminal pushes the batt. quite strongly towards the positive terminal .

The negative end of the batt. is totally flat and very slick , which does not allow prying out from that end . The pry-tool has nothing to grip so it just slips out.

The stationary positive charging terminals are 'recessed' a little under the plastic housing of the charger at each slot. So the batt. can't come straight up & out cause it gets caught on the recess lip of the case. Therefore you must insert pry-tool above the positive terminal of the batt. and push the batt. toward the negative 'springy' charger terminal as you pry the batt. up and out......whew :sweat:.

That strong prying action is what damages the wrapper label on the battery . It's just plain difficult to get one battery out of the charger so you can insert another to charge . I can't find any other way to get em out !

Just wanted to alert everyone , if you get one , get ready to PRY .

?????? are many other chargers this way / or is it just ME ??????


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## TooManyGizmos

Mr. SilverFox

While you were testing this MH C808M charger did you have any trouble removing any of the batteries from their slots .

Is the case designed that much differently from it's sister model MH C801D which won't give em back ?


Thank you for sharing your extensive knowledge !


====================


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## BVH

TMG, the 808 is quite different. Because its made to charge the larger C and D cells also, (near the top of the charger) there's tons of room/spacing between AA's & AAA's at the bottom of the charger. If, however, you were charging C's or D's, you might have the same issue. Don't have any so have not tried. Must admit, the AA's look lost way down there in the bottom of the charger. Look at the dimensions of both. The 808 is quite a bit bigger. The more mass/surface area/space between cells probably results in better cooling.


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## TooManyGizmos

BVH said:


> TMG, the 808 is quite different. Because its made to charge the larger C and D cells also, (near the top of the charger) there's tons of room/spacing between AA's & AAA's at the bottom of the charger. If, however, you were charging C's or D's, you might have the same issue. Don't have any so have not tried. Must admit, the AA's look lost way down there in the bottom of the charger. Look at the dimensions of both. The 808 is quite a bit bigger. The more mass/surface area/space between cells probably results in better cooling.





Now i'm thinkin........'wish i'd paid $30 more & got the 808 .............even tho I don't need the C & D ability .

But NO ...........maybe on the other hand.........I'll call em and ask " HEY - why the design flaw ? ?

The technical spec's looked good , but ya can't know about some stuff ..... till ya get it :mecry:


-------------------------------


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## jclarksnakes

Well, I hope I did not screw up. I just ordered the 801. 
 
jc


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## SilverFox

Hello John,

I have not tested the Ansmann Energy 16 charger, but the specifications indicate that it is capable of charging 9V batteries, where the Maha C808M is not. Charging C or D sized cells, the Ansmann will only do 6 cells at a time, where the Maha will do 8. Another difference is the charging rates. The Ansmann charger will take roughly 20 hours to charge a 10000 mAh D cell, where the Maha will only take about 7 hours.

I don't know what current the Ansmann uses for trickle charging, but the Maha's very low trickle charge current is easy on your cells.

Tom


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## SilverFox

Hello TooManyGizmos,

During my testing, I did several charge cycles with 1000 mAh, 1200 mAh and 1500 mAh AA cells, charging at the fast rate (2.0 Amps). I also tested some 600 mAh AAA cells at the fast rate. I did not encounter any battery heating problems at all and all these lower capacity cells charged without problems.

I still think it is prudent to remember the Maha warning, but they may be being a bit conservative...

Edit to add... I have experienced no problems removing any sized cells from the C808M charging bay. There can be some difficulties in getting AAA cells properly inserted, but after you do it a few times, it is not that difficult at all. On the C808M, the key seems to be to insert the - end first, then snap the + end in. Upon removing the cells, you remove the + end first and the cell pops out. There is ample room between AA and AA cells to grab the whole cell and pull it out. C and D cells sit above the top plane of the charger, so they are also easy to install and remove.

Tom


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## SilverFox

Hello Ben,

Heat destroys NiMh cells. Charging above 1C can generate heat, however it is possible to do it with an advanced charging algorithm. The bottom line is that if the cells heat up, slow down the charge rate... unless you are involved in RC racing. 

Tom


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## TooManyGizmos

SilverFox said:


> Hello TooManyGizmos,
> 
> During my testing, I did several charge cycles with 1000 mAh, 1200 mAh and 1500 mAh AA cells, charging at the fast rate (2.0 Amps). I also tested some 600 mAh AAA cells at the fast rate. I did not encounter any battery heating problems at all and all these lower capacity cells charged without problems.
> 
> I still think it is prudent to remember the Maha warning, but they may be being a bit conservative...
> 
> Edit to add... I have experienced no problems removing any sized cells from the C808M charging bay. There can be some difficulties in getting AAA cells properly inserted, but after you do it a few times, it is not that difficult at all. On the C808M, the key seems to be to insert the - end first, then snap the + end in. Upon removing the cells, you remove the + end first and the cell pops out. There is ample room between AA and AA cells to grab the whole cell and pull it out. C and D cells sit above the top plane of the charger, so they are also easy to install and remove.
> 
> Tom




Thank you SilverFox , I am returning my 801 model & getting the 808m model that you reviewed . I will make a seperate new post about the MaHa MH C801D issues .





^^^^^^^^^^^^^^^^^^^^^^^^


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## john2551

SilverFox said:


> Hello John,
> 
> I have not tested the Ansmann Energy 16 charger, but the specifications indicate that it is capable of charging 9V batteries, where the Maha C808M is not. Charging C or D sized cells, the Ansmann will only do 6 cells at a time, where the Maha will do 8. Another difference is the charging rates. The Ansmann charger will take roughly 20 hours to charge a 10000 mAh D cell, where the Maha will only take about 7 hours.
> 
> I don't know what current the Ansmann uses for trickle charging, but the Maha's very low trickle charge current is easy on your cells.
> 
> Tom


 
Tom,

My next charger will be the MH-C808M, especially for my CTA 12000mAh D cells!

Thanks,

John


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## Ben H

You'll love it John! I just got the 808 with some CTA C & D cells. I love the 2 amp charge rate of the 808. I don't know why there aren't more chargers that charge at a higher rate.


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## wptski

Tom:

You and your darn reviews!  I'll have mine on 1/20/06. :wave:


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## wptski

Tom:

What brand of ruler did you use to measure the size of the MH-C808M? :nana: Before I ordered, I had just the spot for it! I opened the box.  A bit more than 7.5"!!


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## SilverFox

Hello Bill,

Thomas Distributing lists dimensions for the charger as 12.63" X 5.25" X 3", that is about what mine comes in at. You have to add about an inch when you plug the power supply cord in... and of course there is the size of the power supply at 5.125" X 2.25" X 1.18", but I put that down on the floor.

Yours (at 7.5") must have been stepped on during shipping... :nana: 

Tom


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## wptski

SilverFox said:


> Hello Bill,
> 
> Thomas Distributing lists dimensions for the charger as 12.63" X 5.25" X 3", that is about what mine comes in at. You have to add about an inch when you plug the power supply cord in... and of course there is the size of the power supply at 5.125" X 2.25" X 1.18", but I put that down on the floor.
> 
> Yours (at 7.5") must have been stepped on during shipping... :nana:
> 
> Tom


Tom:

You got that backwards! Look at your dimensions in the first post. That's where I got the 7.5" from!!


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## wptski

Here a picture of the charger in action:








Pulses are very small, 114mv. I looked at one their early pulse chargers, a C210 and the pulse are about 500mv.

EDIT: Replaced picture with a closer look and more accurate reading.


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## jclarksnakes

...I got my Maha C801D today. My multimeter and it's battery test function says my Powatech 2300 and 2500 NIMH AAs are coming off this charger much better charged than they were coming off my Powa 888 charger. As was previously mentioned the little battery icons on the display are hard to read unless you get your eyes in line with the angle the display is facing. It would be nice if the display was larger for us older folks. 
...Problems removing AA batteries from this charger??? I find that it works to pop AA batteries out of the charger using my thumbnail at the positive end of the battery like a wedge between the end of the battery and the charger. Forcing my thumbnail in between the end of the battery and the charger very slightly compresses the spring contact at the negative end and then the positive end can be easily levered out with the thumbnail. It is really easier than it sounds but may be difficult for someone with real short thumbnails. IMO if you do not have C or D cells to charge and you have a stout thumbnail this charger is the way to go. 
jc


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## wptski

After reading the review I thought that I'd have problems removing or inserting AA cells. I had no problem at all. I just used the same procedure that I've always used on all my chargers. Insert negative end first and push the positive end in. Just reverse to remove. No problem here!

Yes, the LCD icons could have been bigger and bolder.


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## SilverFox

Hello Bill,

Oops, I was giving the dimentions of the C801D. It is smaller. I have fixed the first post.

Thanks.

Tom


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## SilverFox

Hello JC,

I am glad you figured out a way to get the AA cells out, have you tried any AAA cells?

Tom


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## jclarksnakes

Tom,
....Yes, I have charged AAAs with it and they are not quite as tight a fit between the contacts and are easy to get out just pulling on the positive end of the battery with index finger fringernail. Thanks for the work you have put into doing these reviews of chargers for us. 
jc


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## wptski

Tom:

I used a Fluke 54-II dual input thermometer with two bead K-type probes which has been checked against a lab grade therometer, wrapped several turns around two Duracell 2300mAh cells. In soft mode I get a max of 105F and in regular mode I get 117F. Way cooler than any charger that I've checked but much higher than your 96F reading. Readings agree with a IR temperature probe too.


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## bcwang

Tom,

Do you know how the conditioning algorithm works on this charger? Such as charge current, discharge current, any rest time in between, etc.... 

I'm asking because I have the 808m and I tried the conditioning feature, but it didn't work as I expected. First, it charged. Then, it discharged, but somehow all batteries started discharging at the same time. Sounds like too much a coincidence, maybe I took my eye off it too long. Later I saw some of the AAA cells switch from discharging to charging. I went to sleep, woke up 4 hours later and saw the AAA's were still charging. There's no way that could happen unless the second charge was at a much lower current than the specified 700ma. This confused me, I'm going to try doing it again but paying closer attention to what's going on. Only problem is it takes so long to do a cycle.

Also, I'm wondering if the charger rests after the initial charge before starting the discharge like mentioned on the website where I purchased this charger. I'm not sure if I can tell by looking at the charger to see if that happens, but maybe testing you did with your scopes and meters can tell you how it actually works.

Thanks for any info!


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## wptski

bcwang:

No answer for you but I did a quick ckeck this morning on my C808M. All positive and negative contacts are common to eachother! How does it know if it's a AAA installed or a AA, C or D cell?


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## bcwang

wptski said:


> bcwang:
> 
> No answer for you but I did a quick ckeck this morning on my C808M. All positive and negative contacts are common to eachother! How does it know if it's a AAA installed or a AA, C or D cell?



If you notice under the aaa groove, there is a small button that gets depressed when you put in a AAA cell. This must signal to the charger that a AAA cell is inserted and use the 700ma and 350ma rate. All the other cell sizes charge at the same 2amp or 1 amp rate. I only wonder the consequences if that switch failed and a AAA cell is charged at 2 amps.

I tried the refresh again last night on 8 aaa cells, one of them I saw start discharging 1 hour into it since it was a pretty full battery. 9 hours later, all the batteries are charging still and not finished. I really wonder what discharge and charge current the refresh mode uses, especially on AAA batteries.


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## bcwang

wptski said:


> After reading the review I thought that I'd have problems removing or inserting AA cells. I had no problem at all. I just used the same procedure that I've always used on all my chargers. Insert negative end first and push the positive end in. Just reverse to remove. No problem here!
> 
> Yes, the LCD icons could have been bigger and bolder.




I think the problems with cell removal were with the 801d, not the 808m. I have the 808m and it's extremely easy to remove aa and aaa cells since you have enough clearance to grab the entire cell. 

The 801d has no spacing between cells to put your finger, so you can't easily remove cells sandwiched between other cells. If you start at the ends though, you can remove all the cells easily one by one because there are gaps at each end to get your finger underneath to grab the cells.


----------



## wptski

bcwang said:


> If you notice under the aaa groove, there is a small button that gets depressed when you put in a AAA cell. This must signal to the charger that a AAA cell is inserted and use the 700ma and 350ma rate. All the other cell sizes charge at the same 2amp or 1 amp rate. I only wonder the consequences if that switch failed and a AAA cell is charged at 2 amps.
> 
> I tried the refresh again last night on 8 aaa cells, one of them I saw start discharging 1 hour into it since it was a pretty full battery. 9 hours later, all the batteries are charging still and not finished. I really wonder what discharge and charge current the refresh mode uses, especially on AAA batteries.


bcwang:

Ah! Ha! I didn't notice the little button. If one could make the switch and move the cell outside the charger, current could be easily measured. I'll look into doing that


----------



## wptski

bcwang:

I had two AAA that came out of my wireless mouse. I defeated the switch with a piece of wooden taped down. Wires out to a AAA holder. My Fluke 189 shows 1.9A!  What's wrong here? I put the other cell in the charger and watched it charge in 15 minutes and got to 93F!

I connected the other cell outside the charger again, 1.9A or so and got on the phone to MAHA. I should have caught this myself as I had a scope on it the other day(post above somewhere). It's a pulse charger and the current is the same for all cells depending on the mode. The switch changes the pulse rate much slower for AAA. It looks like at least two seconds. One could probably listen to the difference in clicks, comparing AAA's to the others. I'll scope it another time.

They said that the conditioning cycle uses the slower pulsed current for all three stages but I think that Tom was told differently?


----------



## SilverFox

Hello Bcwang,

I have noticed some strange things during conditioning as well. I have been in contact with Maha about it, but have not heard back from them.

I was discharging some C and D cells and half way through the discharge (by the way the discharge current is 250 mA EDIT I was off on this, it is more like 350 ma, but seel post #54 for the real numbers. END EDIT), I added some AA and AAA cells. The cells I added did not charge up first, but gave an indication of discharging. About four hours later, they still indicated that they were still discharging, and I still had the same two bars on the indicator. 

When the first cells I put in had finished their discharge cycle, all the cells began charging. The AAA cells finished charging first, followed by the AA cells, then the C cells, and finally the D cells. In the end, everything ended up fully charge, but like you I noticed that it took a long time.

The conditioning algorithm is supposed to first charge the cells, then discharge them, then charge them back up. You have a choice of the two charging rates. If you put a cell in and push the condition button, you will charge at the higher rate. If you put a cell in, push the condition button, then push the soft charge button, you will charge at the lower rate.

Tom


----------



## bcwang

Bill, 

I was looking at your scope output picture, but I don't really understand it. 114mv is .114v right, so does that mean 114mv over battery resting voltage? Can that be translated into current somehow? Also, though I know the period is 7.754ms I don't see a second pulse so can't determine the pulse rate from the graph. Help me understand the graph better.

It's interesting that the AAA switch only changes the pulse rate, and not the current. But 1.9amp seems too low for the charge current, you can't average that to be 2amps no matter how long the pulse is. From my observations, the click you hear with the charger can't be the pulse rate, as that is far too slow, especially if each charge pulse is only 7.754ms long. Maybe each click is when the charger re-measures the cell voltage to update the progress meter.

Tom,

The soft charge button does seem to affect the initial charge rate, but after the discharge, the charge rate doesn't seem the same. I will definitely try too test it a third time and try to really time each stage.

Do you know if AAA also use a 250ma discharge current? If it does then its odd that after 9 hours I couldn't finish conditioning a set of aaa 850mah cells set at the fast charge current. Even if they were empty at the start, it should take at most 6 hours to finish the entire cycle, maybe 7 max with worse case numbers for efficiency and cell capacity. 9 hours just doesn't make any sense with the data maha provides.

Another thing I noticed with conditioning, after I saw the cells in their final charging state, the conditioning signal went off. Any furthur cells inserted just charge like normal. I want to get to the bottom of how this thing works, it's still a bit baffling at the moment. I hope maha gets back to you soon an answer.


----------



## wptski

bcwang:

Yes, it's .114V higher than the resting voltage before the pulse and after each pulse the resting voltage is a bit higher and it keeps on increasing. The screen I posted is single event, the scope is waiting for a trigger pulse and catches one pulse only.

Well, the 1.9A pulsed isn't really like 1.9A constant current and the slower pulse for the AAA calculates to 700ma. The outcome is a cooler charge. The current was really more like 1.97A. If one wanted to compare, you could time the charge on another charger at 1.97A on cells in the same state of charge(SOC) and compare that to the C808M.

Your right about the clicks! It can't be the pulse rate, way too slow.

I'll try to capture some AAA charging screen and superimpose it with the AA screen.

I just got this scope last week and still learning although I've used automotive scopes, this one is a bit different.


----------



## willchueh

Hello everyone,

I work for Maha Energy and headup the strategic product group - more specifically, our group develops advanced charging algorithms. The ASIC in MH-C801D & MH-C808M was developed by several engineers in our group. I have been watching this thread for a while and thought I would clarify some of your questions: 

1) Unlike most chargers, the MH-C808M (and MH-C801D) uses a dual-stage PWM (pulse-width management) circuit to maintain the constant charging current. The first stage PWM is a high-frequency one (several hundred KHz) and establishes a fixed 2.0A current. This is done all in the AC adapter. Then, based on the microcontroller in the charger, a second low-frequency (on the order of hertz) PWM controller regulates the 2.0A to modulate it to different currents by altering the duty cycle. For example, when you use Soft Charging, the current is 2.0A but the duty cycle is a little less than 50% resulting in an averaged current of ~1.0A. Similarly, when a AAA is detected, the current is still 2.0A but the duty cycle is only 1/3. 

So if you use a ammeter to measure the current, make sure it is time averaged (otherwise you will see the meter oscillate between 0 and 2A). The best way is to use a current-probe on a scope. 

2) The MH-C808M uses a very intelligent conditioning algorithm. In a nutshell, the charger will let the batteries to rest until all batteries are charged before going to discharge. Similarly, the charger will wait until all the batteries are discharged before going to charge. While charging, however, the charger will show the next step (ie. in the initial charge, two batteries might show charge and 6 batteries show discharge - the six batteries are actually "standing by" for discharge. Discharge commences only when all batteries have finished charging.) The purpose of this is to allow for sufficient time to elapse between charge-discharge without waiting too long. Many designers omit the rest time, but is critical for maximizing battery life cycles. 

This is the reason behind the perception of a "long" charge during the conditioning cycle. The batteries actually don't start charging (despite LCD display) until all batteries are discharged. You can detect the moment the charger starts charging when all the CHARGE indicators are on for the first time. 

We didn't want to clutter the already-small LCD with another "REST" symbol so this was the compromise- sorry for the confusion! 

3) The AAA discharge current is at 1/3 duty cycle. If Soft Charging and Conditioning is enabled simultaneously, the discharge (and charge) current is at 1/2 duty cycle for AA and 1/6 duty cycle for AAA. 


William
Maha Energy (North America) Corp.


----------



## wptski

William:

Welcome to CPF! I asked for you today when I called but you were away from your desk. We spoken several times over the years. Thanks for explaining the operation of the C808M and C801D.  I shall explore it's operation with a scope a bit deeper in the near future.


----------



## BVH

William, it is really great when a manufacturer's representative actually takes the time to come here to CPF and participates in the threads. Thank you very, very much. I love my 808!


----------



## bcwang

Hi William,

Glad you could join us here and provide more info for this charger. Let me see if I understand everything.

Charge Currents (even in conditioning mode):
AA, C, D - Normal Charge - 2 amp constant current
AA, C, D - Soft Charge - 2 amp pulsed at a 50% duty cycle = 1 amp average current
AAA - Normal Charge - 2 amp pulsed at a 35% duty cycle = 700ma average current
AAA - Soft Charge - 2 amp pulsed at a 17% duty cycle = 350ma average current

Conditioning Discharge Currents: ( I think I got all this wrong, but trying to just follow the info you gave plus what I know from other sources)
AA, C, D - normal conditioning - 250ma constant current
AA, C, D - soft conditioning - 125ma constant current
AAA - normal conditioning - 233ma constant current
AAA - soft conditioning - 117ma constant current

Maintanence Trickle Current:
AA, AAA, C, D - all modes - 2amp at 0.4% duty cycle for average of 8ma average

A few questions: 

1. In the conditioning mode if only one battery, or if all batteries are identical in capacity and state of charge (so they all end at the same time), is there still a rest period between charging->discharging, and between discharging->charging? 

2. What happens if new cells are inserted, or cells taken out and replaced while in the middle of the conditioning cycle? Does that cell just follow in same phase of conditioning all the other cells are in instead of starting it's own conditioning cycle from the beginning? Based on my observations and what Tom mentioned, this seems to be the case.

3. The manual mentions putting batteries in from left to right and not skipping any slots. It also says to put higher capacity batteries on the left. This is very odd for an independent cell charger. Tom tested it and showed no difference in performance from the different slots, so is there any reason this statement is in the manual? It's actually mentioned quite clearly as a warning message almost, and there are multiple diagrams showing this as how to "correctly" load the batteries. (Interestingly, many of the press photos of this charger show the aaa cells on the left and the D cells on the right, exactly opposite to how the manual recommends battery loading)

My constructive feedback
-The area around the last two slots get warm from some charger circuit, even when not occupied by batteries. The rest of the charger is cold, so maybe that circuitry could have been in the front of the charger or somewhere else where it wouldn't affect cell temperature at all.

-Discharge current quite low, if 250ma is the fastest discharge current, it will take forever to discharge a D cell, even for AA cells I get impatient waiting so long. The C204W discharges at 400ma, and it's a 1 year older charger.

I'm pretty impressed with each new generation of Maha chargers, and this one is the ultimate one yet. I hope it's the last charger I buy for a while. (I've got way too many chargers, says my wife)

By the way William, would I be able to ask you questions on the MH-C204W maybe outside of this thread? I've got tons of questions about that charger as well.


----------



## willchueh

bcwang said:


> Hi William,
> 
> Glad you could join us here and provide more info for this charger. Let me see if I understand everything...



hello bcwang,

I am happy to answer your questions. 

1) This is the summary of the currents:

AA, C, D - Normal charge - 2A
AA, C, D - Soft Charge - 2A x 1/2 duty cycle = 1.0A
AAA - Normal charge - 2A x 1/3 duty cycle = 0.66A 
AAA - Soft charge - 2A x 1/6 duty cycle = 0.33A 

This is the rough charging currents. Actual charging currents are little lower as the charger applies "special" pulses and very brief "pauses". Typical charging current are 95% of these values. 

Conditioning current: 

AA, C, D - normal - 360mA 
AA, C, D - soft charge - 360mA x 1/2 duty cycle = 180mA
AAA - normal - 360mA x 1/3 = 120mA 
AAA - soft - 360x 1/6 = 60mA

Again, the charger has special pulses and pauses during the discharging process designed to enhance battery performance. Actual discharging current are around 90-93% of these values. 

2) If the batteries are identical in charge, there will be no waiting period. This was a design compromise. If we always wait 2 or 3 hours, the total charging time would be too long. So we just made batteries wait for the last one to finish. Granted the last battery wouldn't get the rest, but it also should have the least heat as the other batteries (contributing heat) have already finished discharging. 

3) If new batteries are inserted during discharge, for example, it will skip initial charging and goes into discharge with the rest of the batteries. Similarly, if you insert batteries during the recharging part of conditioning, it will skip discharging and go the charging. 

Hope this info helps! Feel free to email me with questions on other products, or start another thread! 

William


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## willchueh

Many of you are probably wondering WHY Maha decided not to let the MH-C808M charge and discharge different banks at the same time (after all it is suppose to be an independent charger). From first inspection, it does seem like a total waste of time, having one battery wait for another to finish discharging! Other chargers discussed here (like the BC-900) and other Maha chargers can independently charge & discharge. 

Here is why...

When a battery is discharged, all of the energy is dissapated as heat through transistors or resistors. If we are discharging 3 NiMH battery at 1A, that's 3W. For those of you familiar with the temperature of a transistor disspating 3W, you know how hot that is given the small size of most chargers. 

So we have recently found out charging some batteries and discharging others at the same time is bad for battery health. The heat dissapated by the batteries being discharged will heat up the batteries being charged. Batteries can already get pretty warm during charge ... imagine adding another 3W on top of that. 

William


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## jclarksnakes

....This forum is great. I had been running some batteries through conditioning cycle on my 801 and noticed many of the things others have posted here. I was getting what seemed like strange discharge and recharge times. I came back to this thread to ask questions but THANKS to William they are already answered. It is very impressive that the guy from the factory is here on the forum to answer our questions. 

...Thanks again to William and to Tom and to everyone else who knows more than I do about the subject and has participated in this thread.

jc


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## bcwang

Hi William,

Thanks for your information about the charge and discharge currents, this helps explain a lot of the behavior some of us are seeing. I didn't know discharge current differed based on soft mode or not, or being a AAA battery or not. Knowing the discharge current based on the setting makes the long conditioning times some of us are seeing make much more sense. I guess the manual isn't entirely accurate (charge currents don't match what you mentioned) or fully informative (missing discharge currents) on the specifications on the charger. 

I'm still wondering about why the manual states:

-ALWAYS INSERT LARGER BATTERIES FIRST STARTING
FROM THE LEFT (e.g. D batteries in slot 1, 2, C batteries in slot
3, 4 and AA batteries in 5, 6, 7, 8).

-ALWAYS INSERT THE BATTERIES FROM LEFT TO RIGHT
LEAVING NO EMPTY SLOT.

- For best performance, group batteries of same size and/or
similar charge together.

Those statements were the first thing to worry me about this indepedent cell charger. I definitely didn't want charging performance to suffer if I didn't follow those rules, but I also want to be able to pull cells in and out at random from the charger without affecting the completeness of charge. Any reason the manual spends so much time dwelling over these, even including diagrams showing how to do it correctly?

By the way thanks for all the help so far, it's been great to have someone from Maha helping us all out here.

Ben


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## willchueh

Ben,

With the MH-C808M, the instructions are designed to minimize the heat batteries exposed to. As you have noted, the right-side of the charger is warmer so we recommend to insert batteries from the left. 

But as Tom mentioned, not following this doesn't have any effect on the performance of the MH-C808M.

So feel free to charge the batteries in any combination, take out charged batteries and replace with new ones! 

cheers,

William


----------



## john2551

Hello William,

I currently use an Ansmann Energy-16 charger that has 16 completely indepedent charging circuits. I have seen them all work independently, so i know this is the case. My question is if i have four 12000mah D cells charging in a C808M charger for almost 8-9 hours at the 2amp rate & they are almost completely charged & then i put in one or two more almost depleted 12000mah D cells, will this cause the almost charged cells to go through another whole complete cycle & in turn another wait of 8 or 9 hours for the cells that were already in there 8-9 hours already?

Thanks,

John


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## willchueh

john2551 said:


> My question is if i have four 12000mah D cells charging in a C808M charger for almost 8-9 hours at the 2amp rate & they are almost completely charged & then i put in one or two more almost depleted 12000mah D cells, will this cause the almost charged cells to go through another whole complete cycle & in turn another wait of 8 or 9 hours for the cells that were already in there 8-9 hours already?



John,

The MH-C808M would "wait" for other batteries ONLY in the CONDITION mode listed below:

1) In the CONDITION mode, the charger will wait for all batteries to finish charging before entering discharge (condition mode is charge-discharge-recharge). 

2) In the CONDITION mode, the charger will wait for all batteries to finish discharging before entering the recharging mode. 

Therefore, if you are not using the CONDITION mode, there is no waiting involved. 

Say you put in 7 12000mAh batteries for 6 hours (BTW the charging time is more liky 7 hours for these, not 9), and insert one completely discharged 12000mAh, the first seven will terminate in about an hours while the 8th one will terminate in another 7 hours. 

In charging mode, everything is independent. Practically speaking, it's 8 separate chargers.

Hope this info helps!

PS: see earlier post why we are doing this.

William


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## john2551

William,

Thanks for answering my question. I think your charger is superb for charging these very very high capacity D cells in just 7 hours, the Ansmann Energy-16 takes more than double that time.

Regards,

John


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## SilverFox

Hello William,

Thanks so much for stopping by, and welcome to CPF.

Now the final pieces of information are falling into place... 

Brilliant work on designing the conditioning algorithm. This allows all the cells to be balanced and become ready for use at about the same time. For multi cell applications, this is very convenient.

I did not mean to stir things up by not following standard protocol, but I was curious as to how this charger worked. Now the conditioning cycle makes perfect sense, and if I only want to discharge cells, I may be able to figure out how to do that and skip the initial charge.

I have some C and D cells that I like to do a discharge cycle on every so often. Since they are almost empty, I am just interested in discharging them, then charging them back up. Kind of a mini conditioning cycle. I think I can figure out how to do that now...

It looks like I was off on the discharge rate. I will go back and edit my comments to reflect reality... 

Tom


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## wptski

willchueh:

You stated in your first post:
>>>
. The first stage PWM is a high-frequency one (several hundred KHz) and establishes a fixed 2.0A current. This is done all in the AC adapter.
>>>
Now that's a continous output, not something that happens at the start of every cycle, or on each seperate channel, right?


----------



## bcwang

Hi William,

I thought of one other question about this charger. What kind of charge termination methods are used?

I know -delta V is one
Probably over temp protection is another

What about delta T/delta time, 0 delta V, or any others such as time limit? I've seen moving window deltaV mentioned on the maha website before, what does that mean?

Thanks again!


----------



## wptski

Here's a superimposed screen in the same time scale using a current probe. The top trace is a AAA cell and the bottom is a AA cell. You can see that the AA cell is pulsed much faster.


----------



## bcwang

Nice graph Bill.

Does the time division say 5 seconds? 

What charge mode were you using for the AA and AAA to produce this graph?


----------



## nickz

Thanks for this one!! I have been looking for a decent charger for some time. Ordered my C801D today. Went with it since I only need to charge the AA batteries. I can come up with something if battery removal is tough. I figure putting a ribbon around each cell before putting them on to charge will do just fine and saves me $30 to boot :rock: .


----------



## wptski

bcwang said:


> Nice graph Bill.
> 
> Does the time division say 5 seconds?
> 
> What charge mode were you using for the AA and AAA to produce this graph?


bcwang:

Yes, it's 5 sec. divisions. They both were in Soft Mode. I have problems with picture size when posting. I try to get it big enough but not so big that one must scroll over to see all. Not sure if it's the forum or what, one day, one byte size works but the next day it doesn't.


----------



## bcwang

wptski said:


> bcwang:
> 
> Yes, it's 5 sec. divisions. They both were in Soft Mode. I have problems with picture size when posting. I try to get it big enough but not so big that one must scroll over to see all. Not sure if it's the forum or what, one day, one byte size works but the next day it doesn't.



Interesting, it looks like for AAA in soft mode, it applies a 2 sec charge pulse every 12 seconds or so. I always thought pulse chargers pulse at a much higher rate, like multiple times per second. But this graph seems to conflict with your earlier graph which shows a pulse of only around 8 milliseconds long. I wonder why they're so different.

Do you notice any pulse behavior at all when charging AA's in normal mode? William mentioned that although it charges at 100% duty cycle, there are special pulses and pauses still.


----------



## wptski

bcwang said:


> Interesting, it looks like for AAA in soft mode, it applies a 2.5 sec charge pulse every 12 seconds or so. I always thought pulse chargers pulse at a much higher rate, like multiple times per second. But this graph seems to conflict with your earlier graph which shows a pulse of only around 8 milliseconds long.
> 
> Do you notice any pulse behavior at all when charging AA's in normal mode? William mentioned that although it charges at 100% duty cycle, there are special pulses and pauses still.


bcwang:

That earlier one was done in the One Shot Mode, maybe not the proper way and was also in Regular Mode too!

I did a AA and AAA cell in Regular Mode charging but the battery in my scope was about to die, so I quickly plug it in the charge before it lost memory. I had to change the settings to see the pulses, so it's a bit different than the Soft Mode. I'll post them tomorrow evening.


----------



## willchueh

bcwang said:


> I thought of one other question about this charger. What kind of charge termination methods are used?
> Thanks again!



bcwang,

The charger uses quite a few cutoff techniques. While I am not able to discuss some of our proprietary technology in great depth, I can say that the algorithm is a lot more complicated than Negative Delta V. 

The combination of algorithms we use is responsible for the low battery temperature given such a high current. 

One thing to point out is that the ASIC used in the charger has an effective voltage step size (voltage resolution) of 1mV. Most chargers use microcontrollers (including many of Maha's other chargers) have resolution in the range of 3 to 5mV. This level of resolution is needed to run some of our algorithm. At the same time, such high resolution also require a superb amount of noise reduction and signal conditioning to avoid misreadings. 


William


----------



## wptski

Here's another scope screen of a AA and AAA cell in regular charge mode. More visible in the AAA trace, there is a variable PWM going on. I think in the AA trace there is a variable PWM where I have it marked as "false peak". There were also times were there was no pulse at all but you can't see it in the traces but I could tell from the scope. This variable PWM happens while that third and last segment is flashing in the battery icon at the end of the cycle. The scale is 2A by 2 sec.


----------



## bcwang

Looks like some of Maha's advanced charging algorithms at work. It's nice to have a scope, you can learn a lot about how things work.

I wonder if this thread should be in the "batteries" forum. I only caught this one because I searched for this charger model. I guess I've never thought of looking in the reviews for discussion about battery chargers.


----------



## bcwang

Hi Tom,

Any chance of posting results of this charger in your "battery charger" sticky? I'd be nice to see how fully charged the cells come off this charger compared to the ones currently in the graph. 

Or are the cells you used for the previous test no longer available to make comparison meaningful?

Ben


----------



## BVH

Noticed something unusual about my 808. It sits by my PC with the power supply unplugged most of the time. The charger body does a awful lot of creaking and poping with minor temp changes. Nothing else in the entire room makes any noises.


----------



## bcwang

BVH said:


> Noticed something unusual about my 808. It sits by my PC with the power supply unplugged most of the time. The charger body does a awful lot of creaking and poping with minor temp changes. Nothing else in the entire room makes any noises.



That is pretty strange. I haven't heard any noises from mine yet, but I"ll be sure to pay more attention.


----------



## wptski

Tom:

You stated that the cells coming off the C808M have somewhat lower voltage than others. I have some new Energizer 2500mAh, rebranded Sanyo HR's cells.

They don't have that many cycles on them so at first I blamed it on that. The cells charged in Slow Mode(1A) and discharged at 1A on my Triton are 200mAh lower than when they are C/D at 1A on the Triton. The cells still don't have that many cycles on them but this has repeated twice!


----------



## bcwang

My feeling on this charger is that it doesn't seem to charge to as high a capacity as my MH-C204W, but it comes off cooler. I think I'm going to spend some time in the next few weeks to do a controlled experiment to see which of my chargers produces what charge results on my batteries.

A thing I find a little concerning is that it seems slot 3 and 4 seem to charge to a higher capacity than slot 1 and 2. I can only say this is true when charging 4 batteries at once as that is my only test scenario right now. I thought it was the batteries at first, but I swapped the positions and it happened again, so then I mixed the batteries up, and it still came out the same way. Slots 3 and 4 came out with higher capacity than slot 1 and 2. They were about 50mah apart. I have to do more testing to verify, and try out the other slots as well.

Tom, when you tested to make sure all the slots in your unit charged evenly, was that charging with all of them at the same time, or did you use one slot at a time and test the capacity after each charge? I've seen a couple of slots go from charging to complete at the exact same time which seems odd. I notice this with a few other independent cell chargers too. I wonder if the signal from one battery completing causes the other ones to trigger finished even if they're not. This needs some more investigation.


----------



## SilverFox

Hello Bill,

It is my understanding that the Maha C808M is designed to get the most cycle life from your cells. The cost for this is slightly less capacity. This charger does not overcharge cells at all, not even a little bit. Thus the increase in cycle life.

Tom


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## SilverFox

Hello Bcwang,

My charger is very consistent from slot to slot. I tested this with 2 cells, 4 cells, 6 cells, and 8 cells. I know this is not "exhaustive," but it gave me a pretty good indication of its operation.

I have been using some very good Powerex 2500 cells for this testing. They seem to handle hard use (and some abuse  ) very well. A few more cycles in my Mag85, and I will add them to the NiMh shoot out thread.

Tom


----------



## bcwang

SilverFox said:


> Hello Bcwang,
> 
> My charger is very consistent from slot to slot. I tested this with 2 cells, 4 cells, 6 cells, and 8 cells. I know this is not "exhaustive," but it gave me a pretty good indication of its operation.
> 
> I have been using some very good Powerex 2500 cells for this testing. They seem to handle hard use (and some abuse  ) very well. A few more cycles in my Mag85, and I will add them to the NiMh shoot out thread.
> 
> Tom



I'm definitely going to try to figure out if this was a fluke or completely repeatable. I just wish I had a better way to test capacity quickly than the BC900. I do notice the capacity coming out of the 808m after a 30 minute wait before testing in the bc900 is much less than letting the bc900 do a charge and test cycle which has no wait time. I wonder how much that 30 minute wait hurts capacity. I'm talking about the difference between 2250mah against 2550mah which is quite significant.


----------



## wptski

bcwang:

I wonder if that's what I'm seeing also? I charged four cells in the C808M and then D/C the four as a pack on the Triton.


----------



## bcwang

wptski said:


> bcwang:
> 
> I wonder if that's what I'm seeing also? I charged four cells in the C808M and then D/C the four as a pack on the Triton.



Tried these two tests with the same set of batteries. The 808M after 8 hours on the charger at the normal setting (around 7 hrs is trickle), I got around 2230-2370mah depending on the cell or charge position. Only waited 5 minutes or so between pulling the batts out of charger and placing in bc900 tester.

With the C204W, after 8 hours on the charger ( around 5 hrs is with the light green), I got 2510-2540mah depending on the cell. Waited 1 hour between pulling batts out of charger and putting in tester. I had to drive take it to work to monitor the discharge.

So it seems the 808M doesn't charge as fully. My cell imbalance is more of a concern though, the different slots are not performing the same. I did a test of the voltage after coming off the charger last night. The cells ended at 1.39v on the first two slots, 1.40v on 3-4. The last 4 some were 1.40 and some 1.39v but I didn't pay too much attention on the order, but it was mixed. The C204W comes off at 1.41v


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## SilverFox

Hello Ben,

I just pulled 8 cells off of the charger. Most of them were at 1.44 volts. The lowest was 1.43 volts, and the highest was 1.46 volts.

Your cells at 1.39 and 1.40 volts do not seem to be fully charged.

Tom


----------



## bcwang

SilverFox said:


> Hello Ben,
> 
> I just pulled 8 cells off of the charger. Most of them were at 1.44 volts. The lowest was 1.43 volts, and the highest was 1.46 volts.
> 
> Your cells at 1.39 and 1.40 volts do not seem to be fully charged.
> 
> Tom



I should bring my multimeter home to test with, I was actually using the bc900 to test the voltage, it might load the cell a bit dropping it from the resting voltage. If not, it could be from testing the cells after they were out of the charger for 30min-2hrs. My BC900 was in progress at the time so I was waiting for it to free up to measure the voltage coming off my maha chargers. But my cells that measured 1.41v did test out to around 2550mah at 500ma discharge.


----------



## tareed69

I have the c801d version of this charger, it only charges AA/AAA. I have a problem, it has on 3 seperate occasions overcharged my cells. It just happened now, I inserted 2 AAs and clicked the soft mode and condition mode. First it charges before discharges. Problem is, it never quit charging and the batteries got extremely hot. When I pulled them out, the voltage was 1.52 and quite uncomfortable to touch. They were Rayovac 1800 AA NiMH.

Do you think I have a defective charger?


----------



## willchueh

tareed69 said:


> I have the c801d version of this charger, it only charges AA/AAA. I have a problem, it has on 3 seperate occasions overcharged my cells. It just happened now, I inserted 2 AAs and clicked the soft mode and condition mode. First it charges before discharges. Problem is, it never quit charging and the batteries got extremely hot. When I pulled them out, the voltage was 1.52 and quite uncomfortable to touch. They were Rayovac 1800 AA NiMH.



tareed69,

A quick way to check if the charger is working properly:

1) Unplug
2) Plug in power and watch the power up diagnostic... you should see all the symbols go on from right to left (DONE, CHARGE, 3-level battery etc). 
3) After that's done, the screen should remain off with NO symbols at all. You might want to wait for about 10 sec to make sure no symbol pops up by itself.

William


----------



## willchueh

tareed69 said:


> I have the c801d version of this charger, it only charges AA/AAA. I have a problem, it has on 3 seperate occasions overcharged my cells. It just happened now, I inserted 2 AAs and clicked the soft mode and condition mode. First it charges before discharges. Problem is, it never quit charging and the batteries got extremely hot. When I pulled them out, the voltage was 1.52 and quite uncomfortable to touch. They were Rayovac 1800 AA NiMH.



tareed69,

Assuming the power up diagnostic is good, here are some possibilities:

1) 1.50V is a reasonable voltage for NiMH if you tested them immediately off the charger. The charger's absolute cutoff (Vmax) is at 1.60V.

2) How long have you had the cells? Are these recently purchased? If so, your "new" cells may not be new at all. I would bet the Rayovacs are at least 18-24 month off the production if you'd just purchased them. Cells like these develop a extremely high impedence due to prolonged storage and would cause high temperature (~130F) when first charged. If the cells are manufactured well, then the impedence should drop after a few cycles.

Hope this info helps!

William


----------



## tareed69

Thanks for the response, the batteries are ancient, that probably is the problem.


----------



## TooManyGizmos

willchueh : Please help ..........

For the first 3 weeks my MaHa C-808-M charger worked just fine ................

But now :

I'm having problems too . 
When I insert the first AA battery in the far left slot - and within 2 to 8 seconds press the soft charge button - it won't go into soft charge mode . The word softcharge won't appear on the display . I am pressing and holding the button for 5 seconds - but still nothing .

If I press condition - the word condition will appear - so that function seems o.k.


I have un-plugged *AC* power - and the *DIN* connection cable , waited 5 minutes - then plugged all back in so it would re-set and go thru *self test* - all batt. symbols blinked from right to left . I wait 5 minutes after selftest has finished B-4 inserting battery and pressing softcharge button . I have done this whole proceedure several times , but still can't get it to go into softcharge mode . The word won't appear in the display. The first batt. icon on left will register and start blinking as it normally does and the white display light is working......but no softcharge .

Also have tried several different AA batteries - they are all 2600 MiAh's - 2 months in use - and have been thru at least 6 charges on this charger in 3 weeks and all was fine till now .

Have done ALL I know to do - can you offer any advice , thanx willchueh , for you help.


----------



## willchueh

TooManyGizmos said:


> When I insert the first AA battery in the far left slot - and within 2 to 8 seconds press the soft charge button - it won't go into soft charge mode . The word softcharge won't appear on the display . I am pressing and holding the button for 5 seconds - but still nothing .



TooManyGizmos,

During power-up, the "CONDITION" and "SOFT CHARGING" icons should remain on while the batteries symbols are cycled from right to left. 

Do you see SOFT CHARGING icon displayed during power up?

William


----------



## TooManyGizmos

willchueh said:


> TooManyGizmos,
> 
> During power-up, the "CONDITION" and "SOFT CHARGING" icons should remain on while the batteries symbols are cycled from right to left.
> 
> Do you see SOFT CHARGING icon displayed during power up?
> 
> William


_________________________________


YES ........ william ..... Softcharge icon does show during power-up -goes away at end of self-test.

 But the words chrge complete over the 3rd and 4th batt icon don't show on power-up - all others do. the display dont light up on power up so its hard to read- but thats what it says. What does this indicate ?

The lettering on this display is too tiny to read - especially when it's not lit up during power-up.


_____________


________________________


----------



## bcwang

I just checked mine and the words "charge" and "done" do appear over every slot during the self test. Sounds like you have something wrong with yours, maybe the "soft charge" button is broken.


----------



## bcwang

TooManyGizmos, 

Have you found out what the problem with your charger is yet?


----------



## TooManyGizmos

It's broke .

willchueh , in a PM , suggested I return it to MAHA for a replacement which is what I'm doing. Soft charge just stopped working after 3 weeks


----------



## bcwang

I found a review of the 801D which is pretty much the same as the 808M except it can only take AA/AAA cells. It confirmed the same thing I found, the completeness of charge is not as good as the C204W. Here's the link for anyone interested in reading it. http://www.imaging-resource.com/ACCS/C801D/C801DA.HTM

If Tom is getting such good completeness of charge results (comparitively speaking) with the 808M, I wonder if the C204W would top the charts.


----------



## TooManyGizmos

TooManyGizmos said:


> It's broke .
> 
> willchueh , in a PM , suggested I return it to MAHA for a replacement which is what I'm doing. Soft charge just stopped working after 3 weeks


________________________________________________

I contacted MAHA by phone.

They promptly sent me a new charger with paid postage sticker to return broke one.

So far - so good - on new one . Time will tell . If anyting further develops - I'll post .

.


----------



## picard

cool charger. I will order it. I hope it will do the job. What kind of NIMH batteries can it handle? can it charge all types of niMH batteries??


----------



## TooManyGizmos

picard : 

Yes....that's my understanding ......Type : AA,AAA,C,D-NiMh -even the new Eneloop's .


by the way , picard...........what planet are you visiting right now - how's the weather ?

Got enough gas to get home ?...............got milk ? :buddies:


.


----------



## Tako

Hello 

I can understand that William is not able to discuss their proprietary technology. But at least, I want to know whether there is any maximum battery capacity limit for safe charging using this charger.

For instance, If you use Negative Delta V cufoff technology to finish charging of NiMH cell, at least you need to have 0.33C charging current (for instance 3.3Ah for 10,000mah D cell battery) , but this charger has just only 2Ah .(of course he has already mentioned that this charger has a lot more complicated algorithm than Negative Delta V.)
If the charging current is too low compared to battery capacity (like charging 15,000mAh D cell with 2Ah charging current), I guess almost impossible to detect cutoff point without using a timer cutoff. (From my understanding, the impossibility is not matter of charger resolution, just matter of battery behavior with such low charging current(2Ah) itself. OR if there is other way to detect cutoff point, please let me know.) 

So, what do you think that charging large capacity D cell such as 12,000mah or much larger capacity NiMH cell without having timer cutoff ?
Is it really safe? (With bad luck, endless charging?)

Anyone, please answer my question.


Thanks.

If I have a lot of mistake in grammar, I apologize your inconvenience.


----------



## flashlight

Tweek said:


> Sounds like I might need another charger... :naughty:
> 
> Did a quick search and it can be purchased from several places:
> 
> Thomas Distributing for $99.97 (I like these guys, been buying stuff from them for years)
> 
> Eastgear $96.36 (Never heard of them before, found with Google)
> 
> Direct from Maha $109.95 (Do you really want to pay full MSRP?  )
> 
> 
> Chris
> 
> 
> EDIT: Fixed my spelling!



Just wanted to mention that Eastgear is based in Singapore, they have a brick & mortar store as well as an online webstore. They are reputable, have good service, a wide range of products like Sanyo batteries at reasonable prices & they sihp internationally. I don't have any business interest with them but am a satisfied repeat customer that's all. :thumbsup: Now I'm seriously considering to get the Maha 801D too as I use mostly AAs & AAAs! (already have the 401S & MHC777PLUSII, unfortunately they don't have the 204W)


----------



## bcwang

SilverFox said:


> Update:
> 
> William of MahaEnergy told me that the flashing Done that I am seeing at the end of the charge while charging NiCd cells is not an error message. It simply means that the charge was terminated on high voltage, rather than on delta voltage.
> 
> I also added some information about the lack of an on/off switch in the first post.
> 
> Tom



This is odd. I just charged 4 Sanyo NiCd cells yesterday and they completed with a regular Done, not flashing. Maybe some formulations of NiCd cells complete charging at a lower voltage than others.


----------



## bcwang

Does anyone know what the cutoff voltage is for the conditioning feature of this charger? No one has mentioned it and I wonder if anyone has measured it.


----------



## bcwang

bcwang said:


> Does anyone know what the cutoff voltage is for the conditioning feature of this charger? No one has mentioned it and I wonder if anyone has measured it.



Ok, wptski tested it for me and it cut-off discharging at 1.06v. That's not too low of a value. It's also quite a strange number to choose. I wonder how Maha came up with this value.


----------



## Flea Bag

I bought my 808 from East Gear. Went straight to the shop. Good service!

Since this seems to be the most comprehensive thread about the C808M, I'd better post some of my findings here to centralize all the information gathered on this charger. So far, the charger has been quite impressive until these two (possibly related) problems appeared:



Observation 1:
During conditioning with slow charging rate, the charger's LCD display has a tendency to freeze at the end of the discharge cycle. This has happened two times out of three so far in the following example:

Currently, I have been slow conditioning 4 old NiCd "C" size batteries (1600 mAh each) in the first 4 slots and two Sanyo "AA" 2500 NiMH cells in slots 5 and 6.

The routine start-up sequence takes place and then I activate the "Soft Charge" feature and immediately the "Conditioning" feature to start slow conditioning the batteries. The charger starts by charging the cells and then a while later, it starts discharging them. So far, so good.

However, when the charger reaches the end of the discharge cycle many hours later, the display becomes stuck and all the blinking icons stop. The display is left blank with only the "Condition" and "Soft Charging" icons showing.

I thought the charger would eventually snap out of this frozen display mode so I left the charger alone and didn't press any buttons. Two hours later, the display was still frozen!

Pressing any of the buttons won't get the charger to wake-up and neither will inserting or removing batteries from the slots. The only other option is to switch off the mains power and switch it back on.

After this, the charger will behave like usual again; running the standard power-on sequence. Then it will proceed to charge the same batteries in the charger. Unusualy, the batteries are shown to have at least a half to full charge.

So this either means that:

a: The frozen display did not have an impact on the charge-discharge-recharge cycle.

or 

b: The charger did not properly drain the batteries in the first place.



Observation 2:
During power-up (without batteries in the charger), the charger performs as described. The LCD display has "Condition" & "Soft Charging" showing while the battery icons and the words "Done" and "Charge" are flashed one by one from the right of the LCD screen to the left. Then the display shuts off completely.

However, when a battery is inserted into slot 1 (left most slot), everything proceeds as usual until the charging sequence begins. From here on, the "condition" word doesn't seem to disappear completely. The word appears to be half-activated. It's not as dark and bold as during the start-up sequence but it's not completely deactivated either.

It's quite easy to spot this half-activated word. After about 5 seconds, the "condition" word finally disappears completely. As long as there is a battery in the first slot, this half-activated "condition" word will appear and then disappear a short while later.

Does anyone else have this problem? Do you think it's related to the conditioning cycle's frozen display?


----------



## SilverFox

Hello Flea Bag,

This post should answer your questions about the discharging cycle.

The Condition icon does not show up on my unit unless I view from an extreme angle. It does show for a few seconds when the battery is first placed in, but then it just fades out.

Tom


----------



## bcwang

I've had my 808M lockup on me twice I think. Both times were while conditioning. One was inserting new batteries in while a few had been conditioning for a few hours. Pretty much seconds after that the display had frozen. The second time was just sometime in the middle of conditioning everything froze. I'm not perfectly sure of what other circumstances in this case were, but I'll try to pay more attention if it happens again.

I've never seen the condition light up half way. I do see it at extreme angles like Tom, but at normal angles I don't remember seeing it light up unless I push the button. I'll try to pay close attention to it tonight.

Update:
Well, just got home and tried it and I see what you mean. I guess it's so light I just never noticed it. But I doubt that means anything is wrong with the charger, it's probably just some slight programming bug that has a bit of voltage going to that LCD segment until the charging starts up. If ours both do it they probably all do it.


----------



## willchueh

Hello Flea Bug,

Thanks for the purchase. To make the long answer short, both of your observations are normal. Let me explain:

1) When the first battery is inserted, the CONDITION will be "half-lit" for about 10 seconds. After that, it goes away. However, in that period of time, it will become "fully lit" if the conditioning mode is activated. 

There's no particular reason for this behavior, but all units exhibit it.

2) During discharge, it is possible for all the battery icons to disappear. In other words, "no battery symobls" actually indicates a particular battery state. Toward the end of the discharge, it is possible for all symbols to disappear while only CONDITION remain on. This is particuarly likely when you do SOFT CHARGING plus CONDITION since the discharge rate is cut in half (~150mA) and the screen may remain in this state for a while.

Inserting and removing batteries would not cause the display to change since the charger is still in discharge mode. The only way to get out of this mode (without resetting power) is to remove ALL the batteries thereby quiting the discharge mode. If you are successful, the CONDITION symobl would disappear. Then you can reinsert batteries and they would go straight to charge and the battery outline icons can be observed.

Hope this answers your questions.

cheers,

William


----------



## bcwang

Hi William,

In my case I know the charger was locked up because the icons just stopped flashing. Even after removing the batteries the icons still remained in the same position. Nothing did anything until I unplugged and replugged the power cord.


----------



## Flea Bag

Thanks a lot you guys! I must adimit I did not expect your responses so quickly given the thread was untouched for over a week.

William, thanks for the clarification. Glad to find that my charger is normal as far as the half-actiavted "condition" word is activated.

However, as for the frozen display during the discharge cycle, there is still the same problem. Like what bcwang said; when the display is frozen, even when I pull out all the batteries in the charger, the display still remains frozen showing only the "Condition" and "Slow Charge" icons. Additionally, the LED backlight is still lit although there are no longer any batteries in the charger.

The only way to get the charger out of this freeze is to switch it off completely. It's still just a minor issue I guess, but it could be a time-consuming problem when the display goes frozen again and I have start the conditioning process all over again and wait another day to finish conditioning my batteries.

I wonder if it's the heat of the Singapore air that makes the charger want to 'freeze' itself! :lolsign:


----------



## willchueh

Flea Bag,

Can you try and let me know if the charger freeze if you just do CONDITION without the SOFT CHARGING. This setting is faster and should produce better stability. 

BCWang: do you remember when your charger froze whether it was in regular CONDITION or SOFT CHARGING + CONDITION?

William


----------



## bcwang

Hi William,

Sorry, I cannot remember the exact circumstances of the freeze. Next time I will pay close attention though. It's a great charger otherwise. I use it everyday.


----------



## Flea Bag

Thanks for the offer William, I'll keep you updated if any more freezes occur... Still, I quite like this charger!


----------



## Flash007

The current charge for various cells in Ansmann Energy 16 :

- AAA : 300mA
- AA : 700mA 
- C/D : 1000mA
- 9v : 70mA

For the moment, I don't know the trickle charges's current, but I have asked the question at Ansmann technical support.

For 12Ah D cell (like CTA), the Ansmann will take approximately 15 hours to complete the charge. 

I own the Energy 16 since 2,5 years and I'm happy with it.
But the Maha 808M looks very interesting, regarding the fast charge at 2000mA.





SilverFox said:


> Hello John,
> 
> I have not tested the Ansmann Energy 16 charger, but the specifications indicate that it is capable of charging 9V batteries, where the Maha C808M is not. Charging C or D sized cells, the Ansmann will only do 6 cells at a time, where the Maha will do 8. Another difference is the charging rates. The Ansmann charger will take roughly 20 hours to charge a 10000 mAh D cell, where the Maha will only take about 7 hours.
> 
> I don't know what current the Ansmann uses for trickle charging, but the Maha's very low trickle charge current is easy on your cells.
> 
> Tom


----------



## john2551

I like my Energy-16 also. I like that it has four 9v slots in addition to the 12 AA/AAA slots. But it is not fast. 1850mah AA's take several hours & 12000mah D's take close to a day. If you want speed the MH C808M is the way to go.


----------



## Flash007

The answer from technical support, concerning the trickle current charge for the Ansmann Energy 16 :


Dear Mr. Kose,

thank you for sending your e-mail.

The trickle charge current is:

charging current
---------------- = trickle charge current / mA
60 

I Hope this information responsed your questions. 

If you have any more question please let me know. 

Best regards,
.....


Thus, trickle charge current are, for :

- AAA : 300mA/60 = 5mA

- AA : 700mA/60 = 11,66mA

- C/D : 1000mA/60 = 16,66mA

- 9v : 70mA/60 = 1,16mA

Do you think these values are low enough to permit the accus to stay in the charger all the time once charged ?

Thanks


----------



## john2551

I leave a few AA cells in the charger for a week or more until i need them. I've been doing this for a year+ now with no ill effects.


----------



## SilverFox

Hello Flash,

I believe you will get better performance and cycle life from you batteries if you do not leave them on a trickle charge for extended periods of time. There have been some studies that suggest that if you are going to leave your cells on the charger, it is better to use a timer to pulse the cells for a few minutes each day with the full charge current.

The normal acceptable trickle charge rate is somewhere around 0.01 - 0.02C. If we use 0.01C, your charger should be OK for AAA cells that are 500 mAh (or higher), AA cells that are 1200 mAh (or higher), C/D cells that are 1700 mAh (or higher), and 9v cells that are 120 mAh (or higher).

Looking at these numbers, it seems that even if you leave the cells on the charger, the AA and C/D cells would still self discharge faster than the charger could trickle charge them. In light of this, I still believe it is better to develop a habit of charging your cells before use. You will usually have enough left in the cell to be able to use them even if they have been sitting for a month or two or maybe even three. If you don't use them within a couple of months, you will be better served with primary cells.

Tom


----------



## SilverFox

Update:

There have been some difficulties conditioning NiCd cells in the 808 charger. William has come up with a work around. I have added this information to the first post.

If you end up with a flashing "Done" when charging NiCd cells and notice that you can't seem to do a conditioning cycle on them, read the work around information.

Tom


----------



## yaesumofo

Great review great charger.

Yaesumofo


----------



## Quickbeam

I purchased the C808m a few weeks ago, and it seems to do a great job.

Doug P.


----------



## europium

SilverFox said:


> ...
> 
> Looking at these numbers, it seems that even if you leave the cells on the charger, *the AA and C/D cells would still self discharge faster than the charger could trickle charge them.* In light of this, I still believe it is better to develop a habit of charging your cells before use. You will usually have enough left in the cell to be able to use them even if they have been sitting for a month or two or maybe even three. If you don't use them within a couple of months, you will be better served with primary cells.
> 
> Tom


Is this also true for eneloop NiMH batteries? That the trickle charge will be less than the self-discharge rate and thus be insufficient to keep the AA and larger size cells fully charged when left on the charger?

P.S.--Many kudos to you Silverfox for all your work and data and reviews.


----------



## SilverFox

Hello Europium,

Sorry, I missed this question until now...

First of all, I don't recommend leaving batteries on a charger for any length of time. After about a day, the cells should be fully charged and removed from the charger.

Next, the response you quoted was a reply to Flash about the Ansmann Energy 16 charger and not the Maha C808M charger. I believe the Maha charger "trickle" rates are lower.

One test I have not done is to leave a cell on the C808M charger for an extended period of time. It could be that when the self discharge of the cell dropped below a certain voltage, the charge process would begin again. This might prove to be an interesting way to maintain cells, but I still don't like leaving them on the charger for extended periods of time.

Finally, the Eneloop cells have such a small self discharge rate it just doesn't make sense to leave them on the charger all the time. I believe the Eneloop cells have to be dormant to minimize the self discharge rate. Constant trickle charging may adversely effect this process, but I am not familiar enough with the chemistry to know for sure.

At any rate, it is possible that you could overcharge and dry out the electrolyte in the Eneloop cells by constant trickle charging, even at very low trickle charging rates.

Tom


----------



## hank

Cross reference this thread:
Maha MH-C800S 8 bay charger
https://www.candlepowerforums.com/threads/137843


----------



## Phlack

I have some D batteries which are slightly longer than they probably should be, causing problems in some devices. The top "botton" isn't very long compared to its base, causing problems with charging (in the accumanager20), as well as some devices that have their + terminal connection slightly recessed compared to its surroundings.

As suggested in a previous thread I posted, I got some small rare earth magnets, and they solve the problem of the connection. But not the length.

The C808M (and the D also, I suppose) sound like the + terminals are also recessed. On top of this, it doesn't sound like there's a lot of play as far as how much room there is. (The accumanager20 is spring-loaded, and there's plenty of room for the slightly-long D battery).

Are the batteries (especially D's) tight fitting as it is, or can it accomodate a battery that's maybe a few millimeters longer?

-Mike


----------



## BrianChan

Silverfox,



SilverFox said:


> Hello Ben,
> 
> I just pulled 8 cells off of the charger. Most of them were at 1.44 volts. The lowest was 1.43 volts, and the highest was 1.46 volts.
> 
> Your cells at 1.39 and 1.40 volts do not seem to be fully charged.
> 
> Tom



I understand that Ben is measuring AA cells when he got 1.39-1.40v. However I get the same voltage on the 6 Maha Powerex 11000 mAh D cells hot off the charger. Another thing I have noticed is the battery icon behaves a bit differently for the D cells I have.


For example:

Charging AA and AAA cells:

'empty battery icon' > 1bar > 2 bars > 3 bars > "Done"

Charging D cells:

'empty battery icon' > 1bar > 2 bars > "Done"

In addition to that the batteries are much warmer compared to AA cells.

Any idea what's happening?


----------



## wooniris

Hi William,

Bought a Maha MH C808M about 3 weeks ago. Has been use intermitantly. Today, after the power-up diagnostics, the no:8 rightmost slot remains light up with a empty battery icon, eventhough there is no battery inserted. On insertina a bateery in the leftmost slot no: 1, the no 8 slot changes to charging even though no battery is inserted. This happens throught all the modes, slow, fast, condtioning etc. What's wrong with the charger?

Thanks

Woon


----------



## etc

Just reading this thread makes me think that charger is too smart for me.


----------



## wooniris

Dear William,

Thanks for the quick PM. Excellent support. Will do as suggested. Thanks

Woon


----------



## SilverFox

Hello Mike,

The 808M has some space for slightly longer D cells, but the spring is very tight. The spring set up with the AccuManager will probably work easier.

Tom


----------



## SilverFox

Hello Brian,

My D cells come off at 1.45 volts. Perhaps you need to do a few cycles on your cells...

I have never watched the charging bars. I will have to see if I can spend some time watching them.

Tom


----------



## meditator

Dear Folks,
Any ideas who has the best prices on the Maha MH-C808M ? Is Thomas Dist. the current best try?...Patrick


----------



## Alin10123

Hi Silverfox. Thanks for this review.
Is there anything specifically that this maha charger can do that the accupower 20 can't do? I know it can charge 4 more cells at the same time. But it's also double the price.
I'm Trying to justify the cost. I will be charging anything from AAA cells to D cells.

Thanks


----------



## SilverFox

Hello Alin,

NiMh battery manufacturers recommend charging at a rate of 0.5 - 1.0C when using -dV termination to insure a strong end of charge signal. I believe both chargers use -dV to terminate the charge.

With that in mind, the AccuPower20 charges at 700 mA, and the C808M charges at 2000 mA or if you select, 1000 mA. The AccuPower20 only charges, and is supposed to have a charging algorithm that prevents large crystal build up (voltage depression). The C808M has a condition mode that fully discharges the cells, then charges them back up. The full discharge method is the recommended method, but I have not heard any complaints from people using the AccuPower20.

I have heard nothing but good things about both chargers.

The AccuPower20 has the advantage of smaller size, is able to operate on 12 volts, it has the ability to charge 9 volt batteries, and costs less.

The C808M has the advantage of being able to charge more cells at a time, it offers 2 charging rates of which both are higher than the AccuPower20, charging high capacity cells is faster because of the higher charge rate, and it has the ability to discharge cells in the conditioning cycle.

Tough choice... perhaps you should get both.  

Tom


----------



## eav2k

My third Maha MH C808M charger just died. The first lasted about two months, the second about a month, and the third about 3 months. They all died the same way, after trying to condition AAA cells. I got this charger from Thomas Distributing; who have the best customer service I have every encountered. I would be willing to try a forth C808M, but if I do get one I will not try to condition AAA cells with it. Has anyone else encountered this problem? Note that prior to these failures the chargers worked great.


----------



## Jeff_Bagley

I've had two 808's fail while charging AAA's. Both Thomas Distributing and Maha have been helpful. My third unit has been running for about a week now, charging AAA's and AA's with no problem. I really hope this one lasts.


----------



## Alin10123

hmm, this may be a problem as i will also be wanting to charge AAA cells with it.


----------



## iocheretyanny

eav2k said:


> My third Maha MH C808M charger just died. The first lasted about two months, the second about a month, and the third about 3 months. They all died the same way, after trying to condition AAA cells. I got this charger from Thomas Distributing; who have the best customer service I have every encountered. I would be willing to try a forth C808M, but if I do get one I will not try to condition AAA cells with it. Has anyone else encountered this problem? Note that prior to these failures the chargers worked great.


 How do they fail?


----------



## Sub_Umbra

SilverFox said:


> ...The AccuPower20 has the advantage of smaller size, is able to operate on 12 volts, it has the ability to charge 9 volt batteries, and costs less.
> 
> The C808M has the advantage of being able to charge more cells at a time, it offers 2 charging rates of which both are higher than the AccuPower20, charging high capacity cells is faster because of the higher charge rate, and it has the ability to discharge cells in the conditioning cycle.
> 
> Tough choice... perhaps you should get both.
> 
> Tom


Those two chargers complement each other very well. I have both of them and together they are the best of both worlds.

The AP2020 is gentle...but may require ~36 hours to charge 10,000 mAH NiMH D cells. It may seem worse in real world situations. Since the AP2020 has only four bays it will take around _three whole days_ to charge a 6 D NiMH set for my CD boombox. The C808M makes short work of them. It's kinda breathtaking...

All of my AAAs get charged in the AP2020. I still use some 1,000 mAH AA NiCads and I prefer to only charge them in the AccuPower since the C808M will revert to it's default 2A charge rate if it's power is interupted for even a half second.

The C808M is so fast that I may charge over 120 NiCad and NiMH cells _while a hurricane approaches_ by using both chargers. (I use, rotate and maintain all of those cells on an ongoing basis.)

For me, I wouldn't want to be without *either* of them. I still hope to run the AP2020 on solar eventually.


----------



## Alin10123

Sub_Umbra said:


> Those two chargers complement each other very well. I have both of them and together they are the best of both worlds.
> 
> The AP2020 is gentle...but may require ~36 hours to charge 10,000 mAH NiMH D cells. It may seem worse in real world situations. Since the AP2020 has only four bays it will take around _three whole days_ to charge a 6 D NiMH set for my CD boombox. The C808M makes short work of them. It's kinda breathtaking...
> 
> All of my AAAs get charged in the AP2020. I still use some 1,000 mAH AA NiCads and I prefer to only charge them in the AccuPower since the C808M will revert to it's default 2A charge rate if it's power is interupted for even a half second.
> 
> The C808M is so fast that I may charge over 120 NiCad and NiMH cells _while a hurricane approaches_ by using both chargers. (I use, rotate and maintain all of those cells on an ongoing basis.)
> 
> For me, I wouldn't want to be without *either* of them. I still hope to run the AP2020 on solar eventually.



:scowl: 

This isn't making it easier. LOL


----------



## Al

eav2k said:


> My third Maha MH C808M charger just died. The first lasted about two months, the second about a month, and the third about 3 months. They all died the same way, after trying to condition AAA cells. I got this charger from Thomas Distributing; who have the best customer service I have every encountered. I would be willing to try a forth C808M, but if I do get one I will not try to condition AAA cells with it. Has anyone else encountered this problem? Note that prior to these failures the chargers worked great.



Uh-oh, I was ready to get a C808M ... will continue to wait ...


----------



## Alin10123

Jeff_Bagley said:


> I've had two 808's fail while charging AAA's. Both Thomas Distributing and Maha have been helpful. My third unit has been running for about a week now, charging AAA's and AA's with no problem. I really hope this one lasts.



Jeff,
How are the AAA's and AA's charging in the 808 still? Is it still working for you? or is it still going bad?

thanks


----------



## Al

Two posts above reporting multiple failures of C808M chargers ... These aren't inexpensive chargers and they seem in general to be well regarded. Still, this is a concern and I have e-mailed Thomasdistributing and requested their observations.


----------



## SilverFox

I have been using my 808 since it came out. I use more AA cells, so end up charging that size more than the others. I only use 24 AAA cells on a regular basis, but I haven't had any problems charging or conditioning those cells.

It would be interesting to know how the charger failed. There were some reports of display problems, but this unit has been basically trouble free.

Until we have more information on the failure mode, this unit remains on my recommended list. 

Tom


----------



## Jeff_Bagley

Alin10123
The new charger (my third) has been working perfectly. I have many more AA's than AAA's and I use the AA's more frequently. It may take a couple of months before I develope some confidence about the chargers reliability with the AAA's. These are very nice chargers. I hope that I've got a good one this time.


----------



## eav2k

It seems that the C808M charger fails, for me, when I try to condition AAA cells. I can't really pinpoint the issue more closely than that. It charges AAA cells just fine, it was only after trying to condition AAA cells that I run into problems. The unit is now blinking done on all bays, with no cells in any of the bays. I have placed every type of cell I have into bays one through eight and it still just blinks Done at me. Also tried disconnecting and reconnecting power with and without cells with no effect. 

I only have three types of AAA cell, I do not know if it was a specific cell that caused the problem. I have 850 mah Energizer cells, 850 mah Lenmar NoMEM cells, and Rayovac 15 minute 800 mah cells. 

So does anyone have any ideas as to what is going on?


----------



## Al

eav2k said:


> It seems that the C808M charger fails, for me, when I try to condition AAA cells. I can't really pinpoint the issue more closely than that. It charges AAA cells just fine, it was only after trying to condition AAA cells that I run into problems. The unit is now blinking done on all bays, with no cells in any of the bays. I have placed every type of cell I have into bays one through eight and it still just blinks Done at me. Also tried disconnecting and reconnecting power with and without cells with no effect.
> 
> I only have three types of AAA cell, I do not know if it was a specific cell that caused the problem. I have 850 mah Energizer cells, 850 mah Lenmar NoMEM cells, and Rayovac 15 minute 800 mah cells.
> 
> So does anyone have any ideas as to what is going on?



A thot .... You mention using Rayovac 15 min. cells. These have an internal disconnect feature that is pressure activated when the cells begin to reach full charge. As the cell cools down continuity through the cell is suddenly re-established. Could this behavior have damaged the charger?


----------



## eav2k

Al said:


> A thot .... You mention using Rayovac 15 min. cells. These have an internal disconnect feature that is pressure activated when the cells begin to reach full charge. As the cell cools down continuity through the cell is suddenly re-estabished. Could this behavior have damaged the charger?



I don't know. Could there be some sort of interaction between the high power of this charger and the disconnect feature of the cell? Still the charger is now completely non functional on any bay with any cell.


----------



## eav2k

One email to Thomas Distributing and they are sending me a new charger, with a mailing label to return the old one. Love the service. I will not however be charging AAA batteries in it. I have two other chargers I can use instead.


----------



## SilverFox

Hello Eav2k,

The shut off with the RayOVac cells should act as if you removed the cell and then re-inserted it. It should start the default charge again every time it trips. It happens quickly, and that may present a problem for the charger.

If the charger doesn't reset back to normal when you unplug it, leave it unplugged for a couple of minutes, then plug it back in, you should contact Maha and ask them what is going on.

The flashing Done indicates that the charge was terminated on high voltage, rather than the normal end of charge termination. This is often seen when charging NiCd cells. However, pulling the cell should eliminate the flashing Done signal.

Let us know what you find out from Maha.

Tom


----------



## eav2k

SilverFox said:


> Hello Eav2k,
> 
> The shut off with the RayOVac cells should act as if you removed the cell and then re-inserted it. It should start the default charge again every time it trips. It happens quickly, and that may present a problem for the charger.
> 
> If the charger doesn't reset back to normal when you unplug it, leave it unplugged for a couple of minutes, then plug it back in, you should contact Maha and ask them what is going on.
> 
> The flashing Done indicates that the charge was terminated on high voltage, rather than the normal end of charge termination. This is often seen when charging NiCd cells. However, pulling the cell should eliminate the flashing Done signal.
> 
> Let us know what you find out from Maha.
> 
> Tom



The charger has been unplugged for days, when I plugged it in all the bays went to a flashing done, this is with no cells in any bay. If I put a cell in a bay the charger does not detect it, instead it continues to flash done.

I have not contacted Maha as Thomas Distributing has agreed to replace the charger.

ed


----------



## dekelsey61

eak 2k or Jeff Bagley,
When you were doing the condition on your AAA batteries with your C808M charger did you put the batteries in the charger side by side or did you leave empty slots between batteries in the charger?
Dan





eav2k said:


> My third Maha MH C808M charger just died. The first lasted about two months, the second about a month, and the third about 3 months. They all died the same way, after trying to condition AAA cells. I got this charger from Thomas Distributing; who have the best customer service I have every encountered. I would be willing to try a forth C808M, but if I do get one I will not try to condition AAA cells with it. Has anyone else encountered this problem? Note that prior to these failures the chargers worked great.


----------



## Jeff_Bagley

dekelsey61

My first 808 failed while conditioning two aaa's. These cells were side by side, on the right hand side of the charger. The failure was indicated by a very small amount of smoke comming from the 7th from the left cell bay. After this occured, the display would ramain lit any time there was power applied to the charger wether or not any cells were present.

My second 808 failed while conditioning eight aaa's. The failure was indicated by flashing cell icons displayed for cell bays 4, 5, 6, 7, & 8 from the left. After this occured, any time a cell of any size is installed into cell bay 4, flashing cell icons are displayed for cell bays 4, 5, 6, 7, & 8 from the left wether or not any cells are installed in them.

My third 808 continues to run correctly while charging and conditioning aa's and aaa's.


----------



## Alin10123

Jeff_Bagley said:


> dekelsey61
> 
> My first 808 failed while conditioning two aaa's. These cells were side by side, on the right hand side of the charger. The failure was indicated by a very small amount of smoke comming from the 7th from the left cell bay. After this occured, the display would ramain lit any time there was power applied to the charger wether or not any cells were present.
> 
> My second 808 failed while conditioning eight aaa's. The failure was indicated by flashing cell icons displayed for cell bays 4, 5, 6, 7, & 8 from the left. After this occured, any time a cell of any size is installed into cell bay 4, flashing cell icons are displayed for cell bays 4, 5, 6, 7, & 8 from the left wether or not any cells are installed in them.
> 
> My third 808 continues to run correctly while charging and conditioning aa's and aaa's.



hmm, maybe a bad batch of chargers? How often do you condition AAA cells in your chargers? I'm anxious to get them and will primarily be doing D and C cells but the occasional AAA cell for my LOD CE.


----------



## eav2k

I received my fourth charger, it is working well. Have not tried AAA cells in it yet.


----------



## eav2k

My fourth Maha C808M charger continues to work well. It has been used often for the past month without any problems. 

I have not conditioned any AAA cells to this point, but have conditioned several sets of AA cells. The conditioning cycle will not restore the Energizer 2500 mah cells that have gone into rapid discharge mode. I am unsure of the effect conditioning mode has on other cells but those cells I have conditioned do seem to be working well. 

I generally use slow charge mode when charging, but even this mode seems to be quite fast. 

I recommend this charger despite having 3 of them fail on me; with the understanding that you should not try to condition cells which feature the internal disconnect that is activated when the cells begin to reach full charge. 

I will try to keep the status of the charger updated.


----------



## cam94z28

How does the conditioning mode of this charger compare to that of the C-9000? I don't really need 8 bays as much as I need properly maintained, fast charging, and long lasting cells. If the 8 bay units will condition as nicely, I might go that route, as the C-801D is about the same price as the C-9000, and the C-800S (longer charging time) is even cheaper.


----------



## Sub_Umbra

cam94z28 said:


> How does the conditioning mode of this charger compare to that of the C-9000?....


AFAIK there is actually no way to *force* the Maha C808M to condition _any_ cell of any type -- only an undocumented work-around that will fool it into a conditioning mode...if you have the time to watch it and fiddle with it.

To condition cells in the 808:

 Load cells into the bays and press 'condition'. The unit will first fully charge all cells.
 Many cells will trip out their bays and fail to condition. Keep pulling the cells that error off and put them aside, replacing them with more cells in the empty bays.
 Eventually (sometimes after a great many 'error-cells') one bay will actually go into condition mode. Then it's time to pull all other cells and replace them with the previously charged 'error-cells,' while the 808 is still _in the mood._ 
 The 808 will not go back into charge-mode until cells in all bays are discharged so if you have more cells to condition you must keep swapping cells for discharge while the 808 is cooperating. If you fail to notice that cells in all bays have finished discharging, or if the power blinks out for half a second _you will lose the condition mode_ and have to begin the process anew to get the 808 back into this work around conditioning mode.
 When the 808 has drained all of the cells in all of the bays (once you stop hot-swapping them) it will begin charging them. As _each cell_ finishes charging pull it and replace it from your stack that you've already run through the machine to charge and discharge.
I think that pretty much sums up the steps to condition cells on the 808. If I've missed any steps I appologise for any omissions, while noting that the above instructions for the advertized conditioning feature are not even briefly mentioned in the instruction page that ships with the charger. I'm sure that Maha could do a better job than I of explaining it to their customers who buy the C808M if the issue was of any importance to them.

I have no experience with the condition modes of any other Maha models.


----------



## cam94z28

Sounds like a good enough reason to go with the c-9000. I just want to put the cells in, spend a few seconds on settings and walk away. Dont want to spend all day watching batteries. It seems the C-9000 would be more appropriate for me. Thanks for the info, I'm sure it will help out in this thread.


----------



## SilverFox

Hello Cam,

Welcome to CPF.

It is not quite as difficult as Sub Umbra makes it out to be. He, myself, and others are just put off by the inadequate instructions that came with this charger. It would have been nice to have this "undocumented" procedure "documented."

First, the problem.

Aged NiMh cells, and NiCd cells can end up with a higher voltage at the end of the charge. The 808 signals this termination on high voltage with a flashing "Done." So far, so good, but, the 808 will not go into conditioning mode from a flashing "Done" termination.

The solution.

The solution is to put a cell that the charge terminates with "Done" instead of a flashing "Done" in slot 1 and select the conditioning mode. The charger will charge that cell, then go into the discharge/conditioning mode. Once the charger goes into conditioning mode, you can add other cells as needed, and once other cells have been added, you can replace the cell in slot 1. 

The C9000 allows you to set both the charging and discharging rates, so it is more versatile, but both chargers get the job done.

Tom


----------



## Sub_Umbra

SilverFox said:


> Hello Cam,
> 
> Welcome to CPF.
> 
> It is not quite as difficult as Sub Umbra makes it out to be. He, myself, and others are just put off by the inadequate instructions that came with this charger. It would have been nice to have this "undocumented" procedure "documented."...


SilverFox,

As usual, you sum things up pretty well. I use the AP 2020 and the C808M and for my needs those two chargers work together very well. Contrary to my ravings I like the C808M well enough that I would buy the exact same charger again, even *if* it was accurately discribed in the ads. It does what it does _for me_ so well that I have no qualms about it's functionality. It is only Maha's advertizing distortions and the lack of a comprehensive owners manual that really leave a bad taste in my mouth. 

*This page* contains a copy of the AP 2020's manual which seems pretty complete and lacks (many of) the distortions and omissions of the one page instruction sheet that comes with the Maha C808M. AccuPower thoughtfuly provides a manual that attempts to make all of the features of their product accessable to the buyer even though the ticket price is less than 60% of the Maha. If I run across the instruction sheet that came with my Maha I'll scan it and put up a link to it. 

While the feature sets of the two chargers are like apples and oranges, at least Accupower makes an effort to explain its product's capabilities to the purchaser. IMO Maha does a disservice to it's product *and it's customer base* by making generalized claims for this high quality product that are not accurately supported in the documentation it ships with.

I would love to be able to do a search for all of my posts about the C808M instruction sheet and edit each of them to reflect that this issue has been resolved.


----------



## Ares

SilverFox said:


> The operators manual also states that you should not leave an empty slot when putting your cells in for charging. Maha does not know why that statement is in there… Anticipating some problems, I did a number of tests starting from right to left, filling the middle slots, and skipping every other slot. The C808M took it all in stride and performed flawlessly. It truly is an independent 8 channel charger – with no restrictions.


 
Here's what I found from the review linked on Maha's product page for the C808M:



DigitalDingus.com said:


> Maha states in the MH-C808M manual sheet the largest capacity battery needs to be placed in the left-most side of a charger slot, followed by the next lowest capacity battery, and so on. Also, there should be no empty slots in between batteries in the charger. The reason for this advisory is because of the nature of larger capacity batteries and smaller capacity batteries being attached to the same electrical connection. If a smaller battery is placed first in line, then followed by a larger capacity battery, the larger capacity battery has the potential to draw more power from the smaller capacity battery, resulting in a false reading.


 
Based on this review, it seems SilverFox's tests should have worked fine, but some of the batteries may not be charged completely (or possibly overcharged?). SilverFox, can you try again and test the battery, in light of this new information? It might explain this post:



bcwang said:


> My feeling on this charger is that it doesn't seem to charge to as high a capacity as my MH-C204W, but it comes off cooler. I think I'm going to spend some time in the next few weeks to do a controlled experiment to see which of my chargers produces what charge results on my batteries.
> 
> A thing I find a little concerning is that it seems slot 3 and 4 seem to charge to a higher capacity than slot 1 and 2. I can only say this is true when charging 4 batteries at once as that is my only test scenario right now. I thought it was the batteries at first, but I swapped the positions and it happened again, so then I mixed the batteries up, and it still came out the same way. Slots 3 and 4 came out with higher capacity than slot 1 and 2. They were about 50mah apart. I have to do more testing to verify, and try out the other slots as well.
> 
> Tom, when you tested to make sure all the slots in your unit charged evenly, was that charging with all of them at the same time, or did you use one slot at a time and test the capacity after each charge? I've seen a couple of slots go from charging to complete at the exact same time which seems odd. I notice this with a few other independent cell chargers too. I wonder if the signal from one battery completing causes the other ones to trigger finished even if they're not. This needs some more investigation.


 
So, bcwang, try putting the batteries in left to right order by mAh capacity. So throw your 2500 mAh's in first, followed by 2,300 mAh's, 2000 mAh's and so on. See if that solves your problem.

*Side story:*
I've been the proud owner of the MH-C401FS for about a year. Unfortunately the darn thing got hit by lighting yesterday, evidently. It was plugged up but the LED's were off. I unplugged and plugged it back in, same thing. I also noticed that when plugging it back up, tiny sparks would fly out of the jack.

Crazy part is, I woke up this morning and tried it again.. and it works again! Although the sparks (just about 2mm long) zip out as I plug it in. Is this normal or not? I never really paid close attention before it started acting up. I know sometimes when you plug a power cord in, it can spark a little teeny bit. I'm not sure if mine is busted or not, and I'm afraid to leave it plugged up while I'm not at my house.

Basically, that's why I'm looking into this charger now. I was looking for reviews when low and behold I stumbled upon this review on CPF. Must say I love this forum! :twothumbs

Also, does anybody know of a Eneloop / Rayovac Hybrid type C or D battery? I was looking to use 8D's in my Maglite, but I don't want the batteries to leak all their energy before I get around to using the flashlight!


----------



## SangYuP

I heard the Maha C800s is exactly the same except the charge time is double. Does this mean that the 800s does trickle charge automatically after the charge is complete? So it goes into trickle once the display says "DONE"? Or does trickle charge only work when conditioning?


----------



## SilverFox

Hello Ares,

Welcome to CPF.

I missed your post when you posted it, so sorry for the delayed reply.

The reason to put high capacity cells toward the left of the charger has to do with the heat from the discharge circuit. If you discharge C and D cells you will notice that the right side of the charger warms up. This is where the discharge circuit is located. By keeping the higher capacity cells away from the heat, the whole charger runs cooler. Each slot is independent, so there is no advantage in charging regarding placement of the cells. 

Since each slot is independent you can also skip slots, or load from right to left, or any other combination you care to use. Just keep in mind that the right side of the charger gets warm.

Lightning tends to over voltage things...  I would toss your old charger and get a new one. The 808 would be an excellent choice.

The low self discharge battery manufacturers will start producing C and D cells with the new chemistry when there are as many C and D cells sold as there are AA and AAA cells. In other words, don't hold your breath...

Tom


----------



## SilverFox

Hello SangYuP,

Welcome to CPF.

The 8xx series of chargers all go into a very small trickle charge after charging. This happens regardless of the charge rate. The trickle charge is really a maintenance charge. While it is not recommended to leave batteries on a charger after the charge is complete, this charger would be easier on cells left in it than most other chargers.

Tom


----------



## SangYuP

Silverfox,

Thank you for the information! That really helps out since I am expecting mine to arrive tomorrow. So the 800s is exactly the same as the 801D except for the slower charge rate, right? Thanks again!


----------



## john2551

Tom,

The funny thing is in the promo pic it show the big cells on the right: http://www.thomas-distributing.com/maha-mh-c808m-pic-win.htm

Someone at MAHA should have read the instructions before taking the pic!

John


----------



## GarageBoy

Also, fan is on the left


----------



## SilverFox

Hello GarageBoy,

I wasn't aware that any of the Maha 8xx chargers had fans...

Tom


----------



## LEDAdd1ct

Now that low self-discharge C and D cells have finally arrived, has anyone had the chance to play with either this

http://thomasdistributing.com/shop/...P_id=&osCsid=0269a6cf0ecbadac7ad49e29ed2e9968

or this

http://thomasdistributing.com/shop/...P_id=&osCsid=83b8bb2b81510fff13789f59dd2b604d

in the C808M?

I am thinking of picking up a bunch of the LSD D size and a pair of the C to use, and was wondering how they do/how they do in this charger.


LEDAdd1ct


----------



## Anders

Hello LEDAdd1ct.

A good choise, they should perform as good as C808M perform on AA and AAA LSD cells, flawless

Anders


----------



## ChuckD

What a great discussion! This is my first post here and I'm not sure this is the correct place for this question so I'll start a new thread if desired. My question is about the C808M tho.

I have around 30 of those solar lights you stick in the ground to illuminate walkways, etc. I did some research on them and found the Westinghouse Europas to be the best, and they are great. Each has two LEDS and two rechargeable AA NiCds. The batteries are labeled IDC brand 900 mAh.

I've been using Powerex NiMHs for my digital camera needs for several years now, 2000 and 2100, and I decided to try them in the solar lights as I retired them from photo use. They work fine.

My question is as follows. Now I have a boatload of rechargeable AA's of various ages and capacities. I'm finding my solar lights are showing uneven charging and suspect many of these well used batteries are failing.
But since the lights each take two batteries, I can't be sure which is the weak one. So, can this charger be used as an indicator of battery health? Obviously if a battery won't charge, that's a clue right there. But is there something about how the charger reacts to a given battery that I can use to weed out the depleted ones?

Also, given that these batteries are charged on a solar charger during the day (possibly not to capacity) and depleted overnight, what's the best strategy for prolonging their life? Would they benefit from periodic conditioning?

Thanks all for your participation, it's been very 'enlightening' (sorry!).

ChuckD


----------



## Sub_Umbra

LEDAdd1ct said:


> Now that low self-discharge C and D cells have finally arrived, has anyone had the chance to play with either this
> 
> http://thomasdistributing.com/shop/...P_id=&osCsid=0269a6cf0ecbadac7ad49e29ed2e9968
> 
> or this
> 
> http://thomasdistributing.com/shop/...P_id=&osCsid=83b8bb2b81510fff13789f59dd2b604d
> 
> in the C808M?


Thanks much for the links. I've been out of touch for a couple months and I've been hoping someone would come out with lsd Cs and Ds for some time now. This is *great* news to me.

Thanks again for the links.

I love this place.


----------



## Canuke

Ditto here. Somebody had said in passing elsewhere that C and D LSD's were out, and I was just about to post asking where they were.

Thanks LEDAdd1ct for the links!

Now I just need to figure out what application I need these for, instead of AA Eneloops in adapters...


----------



## SilverFox

Hello ChuckD,

Welcome to CPF.

While the 808M is a great charger, it lacks analytical capabilities.

If you are in the market for another charger... check out the C-9000. It has the analytical capabilities you are looking for.

You may be able to check voltages and weed out some of your cells. Also, you can measure the voltage of the cell under a load. You can use a resistor as a load and sort your batteries by voltage under load after they are fully charged.

The next step is to check the cells for matching capacity. Your lights use 2 cells in series. If one cell has less capacity than the other, the light will prematurely dim. If you get up early in the morning, you can pull cells from the lights and immediately measure their voltages. If one cell in a set is a lot lower in voltage, or has gone to negative voltage, it was the one that had lower capacity. It takes some time to go through your batteries this way, but it usually works. You can mark the low voltage cells and begin using them together in sets. Or you can set aside the low voltage cells and use the stronger cells.

You can also do this testing with a flashlight.

Tom


----------



## ChuckD

Thanks for that SF, wasn't aware of this analyzer. I was hoping there would be something about a battery's behavior in the C808 that would be a give-away to it's health. 

Thanks again.

C.


----------



## Ares

SilverFox said:


> Hello Ares,
> 
> Welcome to CPF.
> 
> I missed your post when you posted it, so sorry for the delayed reply.
> 
> The reason to put high capacity cells toward the left of the charger has to do with the heat from the discharge circuit. If you discharge C and D cells you will notice that the right side of the charger warms up. This is where the discharge circuit is located. By keeping the higher capacity cells away from the heat, the whole charger runs cooler. Each slot is independent, so there is no advantage in charging regarding placement of the cells.
> 
> Since each slot is independent you can also skip slots, or load from right to left, or any other combination you care to use. Just keep in mind that the right side of the charger gets warm.
> 
> Lightning tends to over voltage things...  I would toss your old charger and get a new one. The 808 would be an excellent choice.
> 
> The low self discharge battery manufacturers will start producing C and D cells with the new chemistry when there are as many C and D cells sold as there are AA and AAA cells. In other words, don't hold your breath...
> 
> Tom




Thanks for the welcome! It seems I missed your post as well, though. I had subscribed to this thread but never received any notification - although other threads notify just fine. But anyway...

Thanks for the info about the heat and battery placement. That makes a lot more sense. The way other sites / people had been explaining it, it sounded like it didn't have independent slots. I've read several places that you should not skip slots, etc. Slightly confusing. I emailed Maha about this, and my charger that was acting screwy. The guy from Maha frankly told me he had no idea why their website stated to do that, and to disregard it haha. I'd post the email, but it's been so long that I've deleted it.

Seems I didn't have to hold my breath for too long for those low self-discharge D batteries, eh? Haha. Thing is, I still have my old charger actually. The Maha guy said that short little "spark" when I first plug it in, is normal. And that if you plug the charger in with the batteries already inside, sometimes it will not do anything at all (e.g. appear to be broken due to a lightning strike, I suppose). So my charger is just fine. Was just a fluke, evidently. I'm still considering this other charger though - but I'm thinking some AA to D battery converters would be just as good, and way less expensive. Those Powerex D batteries are expensive! Thing is, I can't figure out where to buy any 3 or 4 AA to 1 D converters (I'd want them as parallel, not in a series). I found where Warren was selling a few on here, but he doesn't seem to be around anymore...

Any clue where to get those? Perhaps you could PM me, as to not get this thread too horribly off-topic 

Thanks!


----------



## SilverFox

Hello Ares,

You will have to do some searching on CPF. I believe there are some AA to D adapters available, or in the process of being made.

It would be interesting to see how well AA cells stay in balance if they are paralleled in a D holder and charged in the 808...

Tom


----------



## john2551

Ares,

Eastgear & aventrade used to sell 4AA to D parallel adapters.


----------



## Ares

Yeah, they are both sold out. Believe me, I did my homework. I scoured this site like crazy before posting, but I can't find any available.

http://www.eastgear.com/shop/index.php?cPath=29_50
http://www.aventrade.com/baad.html

I see where SilverFox mentioned someone might be in the process of making them here - but after looking, I have no idea whom. Except that Warren guy that hasn't posted in a month.


----------



## SilverFox

Hello Ares,

Check out this thread.

Tom


----------



## servaas

SangYuP said:


> Silverfox,
> 
> Thank you for the information! That really helps out since I am expecting mine to arrive tomorrow. So the 800s is exactly the same as the 801D except for the slower charge rate, right? Thanks again!



Two other (small) differences:

*Power supply*
The 801D has a commercial grade din power connector and an inline brick type power supply.
Thye 800S has a consumer style round connector (same style as 401FS/9000) and a wallwart power supply. 

*Colour*
The 801D is black
The 800S is silver


----------



## Phlack

I got myself some LSDs, finally.

Should I do a conditioning cycle on these?

-Mike


----------



## servaas

Phlack said:


> I got myself some LSDs, finally.
> 
> Should I do a conditioning cycle on these?
> 
> -Mike


Yes, like normal discharge batteries, they benefit from a few cycles before use, and heir capacity will come up slightly over the first few charges.

Jeff
-----------------
Servaas Products - Australian Distributor for Maha Powerex - The worlds best AA battery chargers.
http://servaas.com.au
Visit us at the PMA Australia Exhibition in Brisbane, May 30-June 1, Stand 217. http://www.pmaaustralia.com.au


----------



## hank

Tangential question if I may.
Maha MH-C777, S/N 7718519, had it for years for ham radio battery packs. 
Always worked fine. Recently its power supply died; it's a "MKD-48180800 18V DC 800mA"
I tried emailing Maha USA a month or two ago asking where to get a replacement. No answer.
Charger says "DC 12-18V input" positive center.

What do I look for to replace this?


----------



## Black Rose

hank said:


> I tried emailing Maha USA a month or two ago asking where to get a replacement. No answer.


I contacted them about a month ago for something different. Also no answer.


----------



## NA8

hank said:


> Recently its power supply died; it's a "MKD-48180800 18V DC 800mA"
> 
> Charger says "DC 12-18V input" positive center.
> 
> What do I look for to replace this?




If nothing else, you can always use a little bench type DC power supply. 0-20 volts 0-1 amp minimum would work for you. I'd try it at about 12-15 volts. 

I'd cut off the charger wire about halfway and reuse the connector. You can check if the wire was the only problem by measuring the voltage out of the old supply. If there's voltage there still, the connector just broke a wire.


----------



## zband

Could someone answer this question for me- I have a MAHA 777plus II aka "the battery cooker". If my understanding is correct, it cooks batteries because the charging current 850mAh (ultimately destroying batteries cause it wouldn't shut off). Needless to say I need another charger and because of this, I am leery of maha products. Whats different about 808m vs 777plus II when it comes to battery charging algorithms? I mean even on the soft charge setting the 808 is pumping more than my 777plus - so wouldn't I expect more heat?

Sorry I'm not an electrically blessed....


----------



## Sub_Umbra

The 808 is fast. IIRC it charges at up to 2A(!) but every time I feel the cells they're cool. I charge AAs, Cs and Ds with mine all the time. The 808 is a bit quirky but I don't recall ever hearing anyone complain about it cooking cells.


----------



## zband

I just pick one of these units up. Compared to my maha 777 plus II recharger the AAs charged very quickly (this was on the soft cycle) and best part is they only reached a 109F!

I couldn't even hold the same batteries from 777. The AA and AAA's all charged to 1.46 volts at the end. 

I conditioned 2 AAA energizer cells on soft mode- there was no frozen display and the batteries remained cool. It just took about 8 hours for the whole condtion - charge cycle!

So far so good.

Now if Maha could make a similar charger (like the 808) for Li-Ion cells I would be first in line with cash...I wonder if they read these forums.


----------



## zband

So far I am pleased with the 808. Batteries stay (relatively ) cool. 

But one thing I am miffed about, Checking the status of a charged accupower d-cell (charged about a week before ) on the ZTS test showed 100%, putting them into the 808 the D's started charging and the 808's displayed started from 20%-40% level. Not sure why- even though they go to "done " in about 1 hour on a soft charge....hmmm


----------



## mikevelarde

hello everyone:

I'm noob here at CPF, I had been lurking around for sometime and learn a lot from so many CPF guru here. I just purchase a 808M a month ago from a photoshop here in Manila(they distribute the Maha charger in the Philippines). and these charger perform very well until the the 11th of August. I use the charger to condition and charge my AA,AAA C and D cell, of both nicad and inmh chemistry.

When I plug in the charger on the 11th, I saw little smoke came out of bay no.8 of the charger near the DIN 1 connector, then the LCD display start blinking all the time with a done display on bay no. 8(without any battery in the charger) , I try to unplug and plug the charger again after a few minute, the same thing happens. (blinking LCD display and done on bay no. 8 ):sick2:

I bring the charger to the photoshop, and they replace the defective one with a brand new unit . I hope these unit will last!!:sigh:


mikevelarde


----------



## chewy78

mikevelarde said:


> hello everyone:
> 
> I'm noob here at CPF, I had been lurking around for sometime and learn a lot from so many CPF guru here. I just purchase a 808M a month ago from a photoshop here in Manila(they distribute the Maha charger in the Philippines). and these charger perform very well until the the 11th of August. I use the charger to condition and charge my AA,AAA C and D cell, of both nicad and inmh chemistry.
> 
> When I plug in the charger on the 11th, I saw little smoke came out of bay no.8 of the charger near the DIN 1 connector, then the LCD display start blinking all the time with a done display on bay no. 8(without any battery in the charger) , I try to unplug and plug the charger again after a few minute, the same thing happens. (blinking LCD display and done on bay no. 8 ):sick2:
> 
> I bring the charger to the photo shop, and they replace the defective one with a brand new unit . I hope these unit will last!!:sigh:
> 
> 
> mikevelarde


 That's the first time i heard of that happening. I have that same charger, and it works flawlessly time in and time out. Must of been a defective unit. Maybe the employee who assembled it had a bad day.


----------



## Turbo DV8

The C9000 applies a two hour top-off charge at 100 mA after the display says "Done." Does the C808 charger also apply a "top-off" charge after the display says "Done"? Or does done mean done?


----------



## zband

Paging Silverfox....


----------



## john2551

&/or paging William Cheuh of Maha Corp.


----------



## mikevelarde

I recently purchased about a dozen of the powerex 11,000 mah D cell and proceed to condition 8 of them in the 808. after 5 days. the 808 seems to get stuck at the discharge cycle with 1 bar blinking on all slots without going into the final charging cycle. The 808 seems to be overwhelm by the capacity of the D cell :thinking: and their algorithm get mixed-up because of the time needed to discharge those D-cells????

Paging SilverFox or William Chueh


----------



## chewy78

Paging SilverFox of William Chueh[/quote]

those are two different people lol


----------



## Sub_Umbra

chewy78 said:


> Paging SilverFox or William Chueh





> those are two different people lol


He knows that. He mentioned both as they both likely have a good answer.


----------



## rhymemaze

mikevelarde said:


> I recently purchased about a dozen of the powerex 11,000 mah D cell and proceed to condition 8 of them in the 808. after 5 days. the 808 seems to get stuck at the discharge cycle with 1 bar blinking on all slots without going into the final charging cycle. The 808 seems to be overwhelm by the capacity of the D cell :thinking: and their algorithm get mixed-up because of the time needed to discharge those D-cells????



Does anyone else have trouble or other quirks with the D cells in the 808? I guess these NiMh chargers aren't like LCD tv's (example) getting updated/revised each year?


----------



## Sub_Umbra

mikevelarde said:


> I recently purchased about a dozen of the powerex 11,000 mah D cell and proceed to condition 8 of them in the 808. after 5 days. the 808 seems to get stuck at the discharge cycle with 1 bar blinking on all slots without going into the final charging cycle. The 808 seems to be overwhelm by the capacity of the D cell :thinking: and their algorithm get mixed-up because of the time needed to discharge those D-cells????
> 
> Paging SilverFox or William Chueh


The 808 is a quirky charger. I'd just stop the discharge and recharge the cells and try another conditioning cycle after the cells have a couple of cycles on them. Also, a *UPS* with a *filtered power supply* _may_ reduce some of the 808's eratic behavior in some locations. For a charger often touted as *'Professional'* it seems somewhat intolerant of dirty AC and it goes into amnesia if it loses power for even a half second. Either of these faults would seem to pretty much rule it out for professional use in most Third World countries -- and _at least_ a few First World cities like New Orleans.


----------



## Turbo DV8

mikevelarde said:


> ...the 808 seems to get stuck at the discharge cycle with 1 bar blinking on all slots without going into the final charging cycle.


 
I wonder if this response by William Chueh in the C9000 FAQ thread, is applicable to the 808?



> We've come across a lot of AAA batteries (well-known and off brand, new and old) that have DC resistances exceeding 0.3 ohm. Their open circuit voltage, measured between discharge pulses, actually never reach the cutoff and the discharge continues until the MOSFET is unable to draw current (due to insufficient differential voltage). The under-load voltage will already be 0.8V but the open circuit voltage will still be above the discharge cutoff._As a result, the discharge never ends_!


 
I take this to mean that _if_ the 808 measures the open circuit voltage between discharge pulses (unlike the C9000), that the 808 could also fail to terminate discharge.


----------



## barkingmad

Black Rose said:


> I contacted them about a month ago for something different. Also no answer.



Ditto... resent the email - still nothing - not encouraging!


----------



## Swedpat

I recently purchased the Maha MH C808M charger. LARGE charger in comparison to my former AA chargers...

Great to charge all batteries I need from AAA to D in the same charger. The first charging was 8 12000mAh D batteries. They were fully charged at ca 4,5 hours. 8 AA were then charged at less than 1,5 hours, didn't notice exactly.

Regards, Patric


----------



## Flea Bag

mikevelarde said:


> I recently purchased about a dozen of the powerex 11,000 mah D cell and proceed to condition 8 of them in the 808. after 5 days. the 808 seems to get stuck at the discharge cycle with 1 bar blinking on all slots without going into the final charging cycle. The 808 seems to be overwhelm by the capacity of the D cell :thinking: and their algorithm get mixed-up because of the time needed to discharge those D-cells????
> 
> Paging SilverFox or William Chueh



I think I have the same brand and capacity D cells as you though I only use 4 at a time. My 808M seems to do okay with them and other types or sizes of NiMH but sometimes, it 'crashes' during the discharge phase of conditioning. The 808M seems much more reliable for charging than for discharging.

As mentioned somewhere earlier in this thread, the 808M is particularly sensitive to 'crashes' during the discharge cycle. This seems true for all sizes and capacities of my batteries (Sanyo AAA, AA & Powerex D). For example, if you twist the batteries in their charging slot, knock the charger accidentally or are a bit rough with inserting new cells while other cells are still discharging, then the charger has a higher chance of crashing and staying in the discharge phase indefinitely. This could be related to what another member said about the 808M being sensitive to power disruptions.


----------



## ptolemy

I just picked this one up. I wanted to be able to charge all my bateries in One, so it'll replace bc-900 and some other I have.

Doing my first reconditioning right now. One thing I am missing is the ability to actual capasity of the batteries.

Seems like after it charges it fully, discharges, recharges it would be simple to keep an eye on it?

That's one thing I am missing and I find it important, for with so many different non-branded batteries coming from the asian market via EBay sellers are fraction of the price, It would be nice to find the studs and the duds 

Cheers!

p.s is there a charger that does aa/aaa/c/d's and can to soft charge/discharge/analyze capacity (primarly c and d's cause I have eneloops aa/aaa and chances are they are exact mah as they say)?


----------



## Geogecko

Just ordered one of these. I asked Maha about a year or so ago, if they planned on making a AAA, AA, C, & D version of the C9000, and never got a response. I asked the same question a week or two ago, and never got a response either.

They will probably come out with one tomorrow, which is when I expect my C808M to show up. I'm excited to be able to charge C's now, as many of my daughter's and son's toys use them, and at $5 a 4 pack, it is getting rather expensive to buy batteries after batteries.

So, it still seems like people like this charger, from what I can tell. There were some early reports of some people having some heat problems, but I haven't seen any recently. Hopefully, this will be a good charger for many years to come.


----------



## servaas

Geogecko said:


> Just ordered one of these. I asked Maha about a year or so ago, if they planned on making a AAA, AA, C, & D version of the C9000, and never got a response.


I asked our account manager about this last year also, and MAHA do not have an intention to develop an 8 cell version of the 9000.

The tooling and development costs of a new product are very high, and selling 100,000+ of such a charger may take 10+ years, so it would take too long to recover the investment.

Being able to analyze more than 4 AA batteries can be achieved with a second MH-C9000. Sales of C and D batteries are a small % of AA volumes, so adding analyzer functionality to the MH-C808M would be catering to a niche within a niche, so I don't see that being developed either.


----------



## Geogecko

I can see where you are coming from. I should have clarified where I was coming from, I guess. I meant just a 4 cell version of the C9000, that could also charge C and D cell batteries. Seems like the only cost would be in packaging, for a new mold for the plastic housing. The electronics seem to be there to support C and D charging (the C9000 supports up to 20,000mAh capacity, if I read correctly), so I would think the only changes electrically, may be a firmware revision.

That being said, since they already have an 8 cell charger without this funcionallity, it would cut into it's sales. Granted, not everyone is a battery junkie, so if they just priced it right (higher than the C808M), then only those interested in the added capabilities would buy it.

The low quantity of the larger cell useage probably also explains why Sayno does not make the Eneloop in anything other than AAA or AA.

I guess we just have to live with the C808M for larger cells.


----------



## Turbo DV8

Geogecko said:


> I meant just a 4 cell version of the C9000, that could also charge C and D cell batteries... I guess we just have to live with the C808M for larger cells.


 
Which is sort of too bad, because at $10-$13 a pop for a NiMH D cell, it would seem most crucial to monitor and match those cells compared to a $2.50-$3.50 NiMH AA cell. I think they have marked up the price of the 808 so unreasonably high, and the C9000 not too far below it, that they have sort of locked themselves out of any prospect of finding a spot in their line up between the two where even a 4D cell "C9000" could be profitable. Mention was made that the market for D-cell chargers was relatively small, but likewise the market for 8-cell chargers is relatively small also, yet Maha makes one. So, what's Maha to do? Invest the $$$ to make a 4-cell AAA-AA-C-D "C9000" and instantly obsolete the AAA-AA C9000, just to attract a relatively few C & D users? Or make a C-D only C9000 and, as was mentioned, sell to a niche within a niche? It's not that there isn't a market for a 4-cell AAA-AA-C-D analyzer, I think it's just that they can't find any way to massage it into their charger line up and be profitable.

Someone mentioned that a 4 D-cell C9000 would require a huge power supply, because if it were to charge in the purportedly desireable range of 0.5C range, the power supply would have to be able to deliver 20-24 amps. Double that for an 8-cell version. Yet the 808 charges 8 D-cells at only about 1/6C, yet terminates just fine. So, their 4 D-cell C9000 could charge at a very comfortable 1/3C with the same power supply, and over 0.5C for C-cells. I would think the bigger problem of making a D-cell analyzer would be in dissipating the heat generated by discharging 4 D-cells at the discharge currents which "niche users" might be requiring. Discharging, say, four 12 Ah D-cells at 0.5C would equate to about 30 watts of heat dissipation. At the very least, this would require a large area (bulky charger) and enough ventilation openings to rival a block of Swiss cheese. More realistically, it would require the use of active cooling. Oh well, I am just musing. _Dreaming_ of such a D-cell analyzer is still free, and available today!


----------



## Geogecko

Wow, this thing is gigantic! I guess I should have figured that out with 8 D cells piled in this thing. Unfortunately, these low discharges come precharged, so I haven't used the thing yet...

That said, what I mentioned about them having the electronics done isn't quite true. They would have to at least spin the board, in order to get the contacts at the right spacings...

I enjoyed the previous post, it had a lot of good arguments.

I'm hoping that the C cells will terminate fine on soft charging. For me, 4.5 hours is fine for charging, although from what ppl have said, even at the higher rate, things seem to remain fairly cool...


----------



## Turbo DV8

Geogecko said:


> Unfortunately, these low discharges come precharged, so I haven't used the thing yet...


 
I would say, "Go for it!" From what I've read, "precharged" doesn't mean they are _fully _charged at the factory. Then add to that the normal discharge (albeit LSD) since manufacture, and the cells could be down to less than 1.3 volts, so the 808 shouldn't have any problem terminating on that. Or, a discharge-charge couldn't at all hurt a new cell that has been sitting unused for a spell, so this could be the perfect time to try out that refresh function. Keep in mind that with 8 cells, the total time to refresh could be up to 3 or 4 days for D-cells, depending on charge rate selected. Even at 2 amps, the new C-cells should stay pretty cool on the 808. Just avoid doing anything like soft charge (1A) into a 12 Ah D-cell with a cooling fan over it. I ran into termination problems with active cooling with soft charge. I've since learned active cooling is completely uneccesary with the 808 at any rate with any size cell. Active cooling was a bad habit I carried over from using my BC-900! I have since stopped using active cooling with the BC-900 unless charging at 1 amp or higher, as the cooling also prevents reliable termination. Now I have enough BC-900's that I can charge just a pair in each, just in the outer slots for good ventilation. The 808 has plenty of cell spacing for good cooling. Your 808 will get warmer in the right-side bays, so if I am charging fewer than 8 cells, I start from the left and fill rightward to avoid the warmer area on the right. I mean, I have to be anal about _something_ on the 808, right?


----------



## Geogecko

Ah, you were correct. I loaded her up with 8 C cells, and they are currently soft charging, and the bottom bar is the only one lit up right now...

Guess the crib aquarium will be coming in for a sooner than expected battery change. Oh, well. So far, there is no detectable change in battery temperature, but it's only been 15 minutes. I got my C9000 also charging some AA batteries.

The other thing I am impressed with, are the contacts on these two chargers. They are very well built, compared with the normal spring type of contacts on most chargers. I think this is what helps keep the temperature down while charging, by reducing the resistance of the connections with the batteries.

I think the price of the C808M is a little on the steep side, but I'm over all happy with it so far.


----------



## Turbo DV8

Geogecko said:


> Oh, well. So far, there is no detectable change in battery temperature, but it's only been 15 minutes.


 
Temps only rise appreciably very near the end of charge, although the older and more tired out the cell, the warmer overall it will become. Don't panic if the cells don't at first appear to terminate reliably on soft charge. I've read that it can sometimes take a couple cycles for some cells to provide reliable negative change in voltage at end of charge to trigger reliable termination.


----------



## Geogecko

They seemed to do all right, topped off after about an hour or so. They only got slightly warm.


----------



## regor_nono

Hi. I just got my c808m this week. Actually, I got 2, the first one was a dud, the last 3 bays keep flashing done even if I put healthy cells in them. So I returned it for a refund. I got my second one from another merchant. This one's really great. I'm refreshing my cells now for 3 days.

I had some termination problems though, with new AAAs. But I'm sure it's the soft-charge on a 1000 mAH cell. The soft charge for AAA is 350mA, as I've read previously on this same thread. So that will make 0.35C, not suitable for termination.

I'm waiting for another 2 months to make more money to buy the C9000. Can't wait!

Thanks for the great posts on battery chargers. They all helped me to decide which charger to get. Especially to Silverfox, almost all info I know about rechargeables I got from him.

Thanks! :thumbsup:


----------



## Turbo DV8

regor_nono said:


> The soft charge for AAA is 350mA, as I've read previously on this same thread.


 
Thanks for reminding me of that! Some of my ROV Hybrids won't terminate at 200 mA on my BC-900, and I don't like the higher 550 mA of the Duracell Mobile charger for AAA cells. I'll try the 808 on my AAA's at 350 mA and see how it works out.


----------



## Sub_Umbra

Turbo DV8 said:


> Thanks for reminding me of that! Some of my ROV Hybrids won't terminate at 200 mA on my BC-900, and I don't like the higher 550 mA of the Duracell Mobile charger for AAA cells. I'll try the 808 on my AAA's at 350 mA and see how it works out.


As clunky as it sounds, if you want to *guarantee* that your Maha C808M is charging at the gentler, "soft" setting you'll have have to take the extraordinary step of running it through a UPS.

The Maha C808M doesn't like even the briefest half second dip in power and goes directly into *amnesia* at the slightest power interruption, reverting to back to it's default *'hard charge' setting* no matter how you programmed it to charge your cells.

This weakness could have been avoided with the addition of a cheap, mechanical Mode Switch or even just a few cents worth of flash memory, either of which would hold the user's choice over a power blink. They have not only not fixed this -- they have continued to design, manufacture and sell newer chargers with the very same weakness* for years.*


----------



## regor_nono

Sub_Umbra said:


> As clunky as it sounds, if you want to *guarantee* that your Maha C808M is charging at the gentler, "soft" setting you'll have have to take the extraordinary step of running it through a UPS.



Yes, I'm also thinking of hooking up chargers to a UPS. Right now, I only have my charger hooked up to an automatic voltage regulator, as well as my other sensitive electronics (LCD TV, PS3, etc.), hoping it will be at least a temporary fix.


----------



## GMan4911

Anybody try making an adapter to allow charging telephone battery packs? The terminals on the battery pack are on the back and are the pressure type. If I take it apart, I destroy the battery. The handset has two metal tabs at the base which I can attach alligator clips to. The problem is on the mh-c808m charger - the negative terminals extend out enough that I can attach an alligator clip to but I can't do the same with the positive terminals. I figure an adapter about the size of a D cell with metal tabs at the ends that extend out so that I can attach alligator clips would work. 

Anybody seen anything like that? Good idea? Bad idea?


----------



## Mad-Bassist

GMan4911 said:


> Anybody try making an adapter to allow charging telephone battery packs? The terminals on the battery pack are on the back and are the pressure type. If I take it apart, I destroy the battery. The handset has two metal tabs at the base which I can attach alligator clips to. The problem is on the mh-c808m charger - the negative terminals extend out enough that I can attach an alligator clip to but I can't do the same with the positive terminals. I figure an adapter about the size of a D cell with metal tabs at the ends that extend out so that I can attach alligator clips would work.
> 
> Anybody seen anything like that? Good idea? Bad idea?


 
One easy solution would be to put rare earth magnets in the jaws of your alligator clips, turning them into magnetic leads (no dummy cells required.) I think 1/8 inch diameter cylinders would be ideal because they're around the size of a AAA's positive button and could be mounted in different directions, but I haven't tried it yet. Others around here would probably know better than me. (I've seen posts about soldering and welding magnets to wires, and there are "Magleads" out there, but they're a bit spendy.)

My concern would be for the battery packs since they are wired in series. You would have to cut two holes in the shrink-wrap to have access to the single cells inside a 3-cell pack (as our chargers are only meant to handle one cell per channel.) I think this would be a clever way to condition or charge one cell at a time inside the pack, but there is the possibility of overheating because of the plastic enclosure and the fact it's far away from the charger's temperature sensors. At least you wouldn't have to take the pack apart.


----------



## mandrews58

I've had one for several years now, still works great. Does anyone know if maha has plans for a quality charger that will do cr123?


----------



## hank

> ... to guarantee that your Maha C808M is charging at the gentler, "soft" setting you'll
> have to take the extraordinary step of running it through a UPS.
> ...
> The Maha C808M doesn't like even the briefest half second dip in power and goes directly into
> ... default 'hard charge' setting no matter how you programmed it to charge your cells.

Yeek. That's vitally important as a bad failure mode that could screw up batteries.

Is there any visible indication that it _has_ changed from soft to fast charge, can you even tell it's done that?


-----
Edit to add -- I did ask Maha if there were any versions, or any changes over time, for the way the charger works. Reply was no, no change at all in the model/version.


----------



## Train_Watchman

hank said:


> Is there any visible indication that it _has_ changed from soft to fast charge, can you even tell it's done that?


As far as I know, the only way to tell is to look at it periodically, and see if the little "SOFT CHARGING" text is present on--or missing from--the top right corner of the LCD. 

I haven't noticed that quirk with mine yet, but maybe we haven't had a power drop while it was in use. We've been pretty lucky in that regard this winter, only having the generator come on a couple of times besides its weekly self-tests.


----------



## tslrc

Does anyone know if the MH C808M has had any upgades since this thread started? Possibly tweaking some things to address the issues / concerns some have brought up.


----------



## Swedpat

Hi!

I have been using my Maha MH C808M Charger for a few years now and it has worked good. Until now. I think. I have tried to read the manual without explanation to the problem I recently faced. 
I placed 7AA and 1AAA(3xDuracell 2650mAh, 4xGP 2500 mAH and an Eneloop 750mAh) in the charger for conditioning. From the beginning it showed that all the cells were charging but after a while there was just nothing in the screen. Waited a night until next day and still no confirmation of finished process. Then I breaked the power and started it again. The same thing occured. What do you say; has the charger become faulty? Never seen this before. Just empty screen for several hours(and a night and day).


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## Mr Floppy

Swedpat said:


> What do you say; has the charger become faulty? Never seen this before. Just empty screen for several hours(and a night and day).



I've had something that caused the charger to constantly reset. It turned out to be a bad battery. It would charge and rest but discharging cause the unit to reset. Have you tried a single battery?


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## Swedpat

Mr Floppy said:


> I've had something that caused the charger to constantly reset. It turned out to be a bad battery. It would charge and rest but discharging cause the unit to reset. Have you tried a single battery?



Thanks for the reply!

I tried to do the conditioning with only the 3xDuracell 2650mAh and it has been completed. After that I did the same with 4xGP 2500 mAH and it also succeeded. So I don't know why it didn't work the first time with all the batteries.


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## shredmandan

Need a manual for my MH-808 charger - have been searching the web and can't find one. Can Someone point me to one??

Thanks much!!


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## shredmandan

Swedpat said:


> Thanks for the reply!
> 
> I tried to do the conditioning with only the 3xDuracell 2650mAh and it has been completed. After that I did the same with 4xGP 2500 mAH and it also succeeded. So I don't know why it didn't work the first time with all the batteries.



There are some great tips and comments on Amazon regarding this charger. In one of the reviews the reviewer talks about using another "dumb" charger that will start chargering cells that appear to be "bad" and will charge them up to a level that is required "minimum" for the MAHA CH-808M to start chargeing. If the cells are below a certain voltage (easily done) the 808 will NOT BEGIN to charge. Not sure what a dumb charger would be all though - looking into that and will check back in if I find one.


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## Sub_Umbra

shredmandan said:


> Need a manual for my MH-808 charger - have been searching the web and can't find one. Can Someone point me to one??
> 
> Thanks much!!



There wasn't one when I bought mine. In no way could the one page of text that came with it be called a manual. If it weren't for threads at CPF I never would have ever found workarounds for some of the features claimed in the ads for it...and some of the workarounds are unreliable.

I'm not saying it's a bad charger, only that MAHA should act less like a used car salesman and try to more accurately list actual features that work as advertised on a charger that they charged $100 for.

No offense to any used car salesmen out there...


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## Mr Floppy

shredmandan said:


> Need a manual for my MH-808 charger - have been searching the web and can't find one. Can Someone point me to one??



I bookmarked it! Pity the link is dead but here it is:
http://web.archive.org/web/20121111005211/http://www.mahaenergy.com/download/mhc808m.pdf


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## Artivideo

Did you test this to confirm that if you leave the cell on the 808 that when the voltage drops below a certain value by self discharge, the 808 starts the charge process again by itself ???



SilverFox said:


> One test I have not done is to leave a cell on the C808M charger for an extended period of time. It could be that when the self discharge of the cell dropped below a certain voltage, the charge process would begin again. T
> Tom


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## Richwouldnt

Link in post 232 is no longer dead. Just worked for me. Considering the start date of this thread it must be one of the oldest on CPF that is still relevant for a still produced product. Any one know what changes have been made to the product since it was introduced?


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## magnum70383

I bought it 2 years ago and it looks the same.. I think they haven't updated this charge one bit since when it came out at 2005???


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## WalkIntoTheLight

Shame they never updated the C9000 to take advantage of LSD cells like Eneloops. i.e., Don't stop the charge at 1.47v (rely on -dV instead), and don't top-off or trickle. At least have a charging optional mode that does this, even if the default mode doesn't.


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## breamer

My 808m died yesterday. All eight bays flashing done when empty. Went I put batteries in it just displays a box, not charging indicator , nothing. Four years old , paid 150cdn. I'm going back to the cheap chargers, I could have bought four for that price. It really burns my bag with people tout "Buy quality", my old CCRANE that is twelve years old is still working


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## breamer

As a follow up Maha has agreed to replace the entire unit free. I purchased it in 2009. All I pay is shipping. Which I am ok with

Very happy with the customer service


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## fnsooner

That is awesome breamer. The MH C808M is one of the best investments I have made since I started out in this hobby.


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## Lateck

I know this is an "Older" thread but it is VERY interesting that nobody has made a better charger for NiCd/Ni-MH batteries in 10+ years.
I had asked about changing multiple D cells and every time people would recommend this charger.
I have one in-coming along with C/D Tenergy cells. I look forward to being able to charge my Ni-MH's properly (and more then 4 at a time).
I hope this thread will help others in the same quandary. 

Lateck,


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## mauiblue

I know this is an old thread but I didn't want to start a new one. 

I bought my MH-C808C in 2008 and this year it started to have some problems. The last three bays from the right of the charger was not working. I was able contact Maha service department via email and received a RMA number to return the charger for repair. It cost $30 to repair and $20 for shipping via USPS Priority mail. I got it back and all is well. It is a great charger and I like being able to charge 8 cells at a time. Maha service repair department is top notch. Aloha for looking.


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## ben_r_

Oooooooold thread, but I am getting ready to pick up a C808M charger since it seems to still be the best C/D cell charger out there! Ive had my C9000 for many years now and still LOVE it! Do wish they'd make a smaller/cheaper C404M or something that was a 4 bay charger. Have around 100 AA/AAA Eneloops and cant think of a single time when I NEEDED to charge more than four at a time.


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