Maha MH-C9000 SUPPORT / FAQ - continuation

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Hello Shelm,

As HKJ pointed out the Maha charger uses a 2 hour top off charge after the main charge. With both Refresh and Cycle there is no rest period and the discharge starts right after the top off charge finishes.

The Break In function is a timed function so there is no top off charge included. The closest approximation to the labeled capacity comes from using the Break In function.

Some NiMh cells benefit from cycling as you have observed. If I have cells that have been in storage for awhile or with new cells that aren't low self discharge chemistry I will usually run them through several charge/discharge cycles to "break them in" before running a Break In cycle to see where they stand.

Many people feel that the standard Break In takes too long so they only do charge/discharge cycles and go with the discharge capacity they get under slightly higher discharge rates. In actual practice the results can end up very similar so it is hard to argue against doing that.

The battery industry uses a standard to define the capacity of the cells they produce. The Maha Break In function comes close to following that standard. Sometimes the labeled capacity is based upon theoretical maximum values and the actual capacities will be a little less. Sometimes a cell needs some exercising before it becomes "vibrant" for use. Other times it works well right from the start. In your case it looks like they needed some exercise to get back into shape.

Tom
 
SilverFox said:
Hello Handlobraesing,

You have made an important discovery... Crap cells don't perform well. :devil:

I have found that it is far less frustrating to recycle crap cells and replace them with new cells that are performing well. However, there can be some educational opportunities from playing with crap cells.

If you want to play, try this...

Charge your cells at 1000 mA. When Done is displayed, set a timer for 3 hours. When the timer goes off, start a 500 mA discharge.

Record the capacity you get and compare it to the labeled capacity of the cell.

Leave the cells in the C9000 and set a timer for 30 minutes. Then do another discharge at 200 mA.

When that discharge is completed, once again, set the timer for 30 minutes, then do another discharge, this time at 100 mA.

Next, do a Break-In cycle. Once again, record the capacity and compare it to the labeled capacity.

Set a timer for 1 hour, then discharge at 500 mA.

Record the capacity and compare it with what you got during the first 500 mA discharge. If you see an improvement in capacity, the cell is starting to recover and you can repeat this process again.

After 10 rounds of this, if your crap cells are going to recover, they should be at or above about 80% of their labeled capacity.

On the other hand, if your crap cells are still crap, recycle them and move on. If you have a secial "attachment" to them, find a crap application for them and don't be frustrated when they crap out on you.

Have you tried running any healthy cells through charge/discharge cycles on the C9000? How did they do?

Tom
Click to expand...

Hello Tom!

Should I use your method to improve the capacity of some of my Eneloop AA cells?
I remember also another way to revive crap cells.

12 cycles of Refresh/Analyze @500 mA charge/100 mA discharge.

Thanks for your expertise,

Peter
 
Wolf Lonesome said:
12 cycles of Refresh/Analyze @500 mA charge/100 mA discharge.
Click to expand...

Hopefully Tom agrees with me. 500mA/-100mA is too tame to get a sleeping Enelup back to top condition. You need to train with heavy weights to get bigger muscles. (analogy)
 
Hello Peter,

I have very limited experience with damaged Eneloop cells. The ones that I have tried various things with have not responded.

Degradation usually results from either using up the materials inside the cell or an unequal distribution of the the chemicals inside the cell. When the materials get used up there is nothing you can do. If the chemicals become unevenly distributed there are two schools of thought on this. One involves slow charging and repeated discharges. The other involves higher rate charge/discharge cycling. Both work. The common theme between them is subjecting the cell to charge/discharge cycles.

My perspective is that a cell with reduced capacity due to an imbalance of chemicals in it would respond more favorably and have a smaller risk of damage if you use lower currents over a longer period of time. I have friends that prefer higher current cycling. We both are able to recover cells but I think I have a slightly higher percentage of recoveries so I have a bias toward lower current efforts.

The low self discharge cells have a little different chemistry so as they begin to wear out it will be interesting to try to figure out what helps and what doesn't.

If you are trying to recover some Eneloop cells, consider yourself a pioneer.

Tom
 
Hi Tom!

Thanks for the explanation.
Do you have any suggestion how to use BC-700 or Schulze to regain the lost Eneloop capacity?
You have mentioned somewhere about your success in recovering a few cells using the Schulze charger.
Can you reveal your "secret" :).

Cheers,

Peter
 
Hello Peter,

If I were trying to rejuvenate a cell that was under performing I would start with a "complete" discharge followed by a charge like the Break In mode used by Maha. And then realize that it may take a few cycles of this to make a difference. Keeping track of discharge capacities and voltage under discharge loads will tell me if I am making progress or not.

I have already identified a method to discharge a cell. I may even short it out overnight to get a more complete discharge.

Schulze offers an automatic charge that varies the charge rate depending upon the cells internal resistance. It addition it has a long duration formatting charge setting. This combination seems to help if the damage to the internals of the cell are minimal.

The sequence starts with a "normal" charge followed by measuring the capacity during a "normal" discharge. This is your benchmark and the goal is to get a higher number as a result of your efforts. Next additional discharges are done in an effort to completely empty the cell. Next comes the auto charge and this is followed by 24 hours of formatting charge. Let the cell rest an hour or so then do another "normal" discharge. Compare the results and repeat.

The exciting ones come back after a cycle or two. The others show very little change after a week of effort and you begin to wonder if it may be better to retire the cell and move on...

Tom
 
Hello Tom,

Let say I will first discharge the cells at 100 mA using BC-700 and the run a break in using the C9000.
Then I will end the 16 hour charge and use the BC-700 again for discharge and record a capacity.
Maybe I should I use a diode and resistor to further discharge down to 0.8 V.
I believe, this makes sense...

Can you give me any detailed instructions how to effectively try to recover these 2010 Eneloops?

Peter
 
Hello Peter,

I have very limited experience trying to recover Eneloop cells. I was not successful with anything that I tried. You are on your own here...

Tom
 
I have one from when it was released. Many of us here know that battery performance depends a lot on current. The way it works is causing a lot of problems. Does the newest version have a real algorithm that uses much faster or actual current regulation to actually reflect impact on battery the same as true current level shown in display?

It is just cycling a resistor that corresponds to approximately 1A with a switch and it does it quite slow at once every other second. The voltage is flash reading the voltage under 1A of load regardless of battery size and reading a voltage under load at 1A regardless of it is 600mA AAA and 2500mA AA is unreasonable. It will immediately jump to "done" on slightly tired cells, because voltage drop at 1A is quite a bit.

When you set it to 100mA discharge rate, it draws full load for 0.2 seconds and take a voltage under load, rest for 1.8 seconds and assumes it is the same as drawing 0.1A into a continuous load. Cells terminate prematurely at end of cycle with plenty of cycles left if the load under 1A falls below 0.9v regardless of settings.

On charging, a 2,000mAh battery do not see any productive gain from a 10mA trickle charge, but it will accept charge at 600mA for a second every minute. When you're doing cycle tests, I don't think 1,000mAh battery sees 2A for 0.1 seconds every two seconds for 16 hours the same as a steady 0.2A for 16 hours and I think it causes over charging. I think the rate is slow enough that it acts more like a blinker than actual dimming.
 
Bright+ said:
I have one from when it was released. Many of us here know that battery performance depends a lot on current. The way it works is causing a lot of problems. Does the newest version have a real algorithm that uses much faster or actual current regulation to actually reflect impact on battery the same as true current level shown in display?

It is just cycling a resistor that corresponds to approximately 1A with a switch and it does it quite slow at once every other second. The voltage is flash reading the voltage under 1A of load regardless of battery size and reading a voltage under load at 1A regardless of it is 600mA AAA and 2500mA AA is unreasonable. It will immediately jump to "done" on slightly tired cells, because voltage drop at 1A is quite a bit.

When you set it to 100mA discharge rate, it draws full load for 0.2 seconds and take a voltage under load, rest for 1.8 seconds and assumes it is the same as drawing 0.1A into a continuous load. Cells terminate prematurely at end of cycle with plenty of cycles left if the load under 1A falls below 0.9v regardless of settings.

On charging, a 2,000mAh battery do not see any productive gain from a 10mA trickle charge, but it will accept charge at 600mA for a second every minute. When you're doing cycle tests, I don't think 1,000mAh battery sees 2A for 0.1 seconds every two seconds for 16 hours the same as a steady 0.2A for 16 hours and I think it causes over charging. I think the rate is slow enough that it acts more like a blinker than actual dimming.
Click to expand...

you're mentioning a very good point relevant in practice/theory. in summary, with poor NiMH's (or new Alkaleaks) the CHARGE and the DISCHARGE programs terminate way too early. this is noticeable especially with higher 'transfer rates' but also with the lowest transfer rate possible: 100mA DISCHARGE rate. (apart from that, the C9000 does not accept cells with HIGH resistance and that happens even to some of my Eneloops!) the reason for this §$%&! behavior is the PWM pulsation of the current, which is still there in 2014 production units.

well that's the way the machine works.

oh.

well.

:rolleyes:
 
Last edited:
kreisl said:
the reason for this §$%&! behavior is the PWM pulsation of the current, which is still there in 2014 production units.

well that's the way the machine works.

oh.

well.

:rolleyes:
Click to expand...

You would think they can tweak the timing of voltage measurement or PWM cycle duration with new firmware.
 
Bright+ said:
You would think they can tweak the timing of voltage measurement or PWM cycle duration with new firmware.
Click to expand...
They could maybe, but discharge and capacity testing should just not be done with pulsed current as its not only inaccurate it does not simulate correctly the typical load characteristics.
 
Hi guys,

I have the Maha Powerex Wizard One MH C9000 loaded in the barrel and all that is left is the trigger pull. With that said, I have read through all the threads/post I could find on here, as far back as 2007. I feel I know all there is to know about this charger, but I thought I would get some final thoughts/opinions from current owners/users on here. A lot of the stuff is a bit dated on here since this charger's debute back in 2007 or so.

I went as so far to email Maha and ask if there has been any updates recently on this model and they stated no. So in a last ditch effort to cross my Ts and dot my Is, I have come here to get some final feedback.

Thanks in advance guys!
 
Last edited:
roadwarrior said:
Hi guys,

I have the Maha Powerex Wizard One MH C9000 in the loaded in the barrel and all that is left is the trigger pull. With said, I have read through all the threads/post I could find on here, as far back as 2007. I feel I know all there is to know about this charger, but I thought I would get some final thoughts/opinions from current owners/users on here. A lot of the stuff is a bit dated on here since this charger's debute back in 2007 or so.

I went as so far to email Maha and ask if there has been any updates recently on this model and they stated no. So in a last ditch effort to cross my Ts and dot my Is, I have come here to get some final feedback.

Thanks in advance guys!
Click to expand...
As the saying goes, "If it aint broke, don't fix it." The C9000 is perfect for charging/maintaining/analyzing. Pull the trigga man.
 
roadwarrior said:
Hi guys,

I have the Maha Powerex Wizard One MH C9000 in the loaded in the barrel and all that is left is the trigger pull. With said, I have read through all the threads/post I could find on here, as far back as 2007. I feel I know all there is to know about this charger, but I thought I would get some final thoughts/opinions from current owners/users on here. A lot of the stuff is a bit dated on here since this charger's debute back in 2007 or so.

I went as so far to email Maha and ask if there has been any updates recently on this model and they stated no. So in a last ditch effort to cross my Ts and dot my Is, I have come here to get some final feedback.

Thanks in advance guys!
Click to expand...


http://www.amazon.com/review/RZCMBYAN3QKN3/
 
I never knew there was a problem charging AAA batteries with this charger. "You will have to push a button 7 times....". Thanks for the Amazon review.
 
recDNA said:
I never knew there was a problem charging AAA batteries with this charger. "You will have to push a button 7 times....". Thanks for the Amazon review.
Click to expand...
To be clear, there is not a "problem" charging AAA batteries on the MH C9000.
I have charged plenty of them on one. Pushing the button to achieve the desired charge rate can hardly be considered a "problem" as far as I am concerned... however YMMV if you consider it an ""inconvenience"". :thumbsup:
 
Thanks for the feedback guys!

After much homework, the Maha Powerex Wizard One MH C9000 is what I am going with. I have feeling I will not be disappointed. :D
 
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