# Deciding on a nice eneloop charger



## llmercll (Aug 27, 2011)

Hello!

I've been using an eneloop charger that came with my "power pack" for about a year now, but being unable to charge a single battery is becoming more and more of an inconvenience. With that said, I'm the market for a solid, quality charger, for around $50, that does single channel charging =p

I believe my choices are between the Powerex MH-C9000 and the La Crosse Technology BC-700, but am very open to others. I've read the Maha is preferred over the BC-700, but not sure exactly why. I've also read about BC-700's catching fire, which is a little upsetting =/

Any input would be greatly appreciated!!

thanks!


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## Mr Happy (Aug 27, 2011)

The C9000 is my preference because among other things it has an overall better build quality, it has the break-in and discharge features, it has a solid warranty backed by good customer service, it is kind to Eneloops because it slightly undercharges them and keeps them cool, and it has a 2 amp charge rate if you need a fast charge.


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## Russel (Aug 27, 2011)

I second Mr Happy. The MH-C9000 is a good choice. In addition, it operates well from 12V power sources, such as a car cigarette lighter (with appropriate adapter) and the default 1000mA charge rate works well with Eneloop AA cells. You can simply place the AA Eneloops in the charger and it will default to a 1A charge rate without depressing a single button.


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## llmercll (Aug 27, 2011)

Thanks for the replies, It does appear the Maha is the superior charger. It's twice as expensive as the BC-700, though. Decisions, decisions...


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## lwien (Aug 27, 2011)

I've been using my BC-700 with all my AA and AAA Eneloops for about 2 years now. Charged the AA's at both 500 and 700 and the AAA at both 200 and 500. Never once missed a termination. 

A few things about the BC-700 that I like better than the C-9000 is:
You don't have to cycle through each battery display to get individual readouts. Each batt has it's own readout. Makes things a bit simpler.
You can globally make settings for all batts other than default. Can't do that with the 9000. If the 9000 is taken off of default, you need to individually set each batt. Also makes things a bit simpler.
When the charger states that it is "done" ("full" on the BC-700), it is actually full, rather than having to keep the batts in the C9000 for an additional 2 hours after it states that it is done, to do a comparable charge.

Both good chargers, in my opinion, and they both excel in certain areas that the other one does not.

One of the main things that the C9000 has that the BC700 does not have is a Break-In mode, but with Eneloops, the advantages of running a break-in is questionable at best.



.


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## Wrend (Aug 27, 2011)

I use the C9000 (ordered a few months ago from Thomas Distributing along with a bunch more of the newer 1500 cycle Eneloops).

It's not a "perfect" charger, but it works really well with Eneloops, especially for my needs.

Here is a recent post of mine in another thread that goes into more detail: http://www.candlepowerforums.com/vb...with-accucel&p=3729890&viewfull=1#post3729890


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## llmercll (Aug 30, 2011)

I'm leaning toward the BC-700. I usually don't charge more than 2 batteries at a time, and if I space them out I doubt heat would be an issue. Not being able to charge at 1000mA isn't a big deal right? I thought the lower the charge rate the "healthier" it is for the cell anyway? 

The warranty and better build quality would be nice, but not worth twice the price in my opinion. My reading supplements what Iwien said, that break-in is questionable with eneloops.

Unless I'm mistaken those are the main differences, and I'm not seeing enough to justify nearly twice the price, do any of you? Maybe I just don't "demand" that much from a charger. Just being able to know the mAh of the battery is going to be awesome for me, haha =p

thanks!


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## DFiorentino (Aug 30, 2011)

I went from a BC-700 to a C9000, so I've had a chance to use both. Am I glad I "upgraded"...yes, without a doubt. Is it worth the added cost, well that is a subjective question. You don't have to "demand" a lot from your charger to justify the cost. Frankly, if I wanted to save money, I would have just bought the C9000 in the first place instead of having to upgrade. The way I see it, if your in the market for an advanced charger and not looking into hobby/RC chargers (which I own as well), you might as well spend the extra money up front to get the added features/build quality. Being able to charge at 2A is immensely time saving versus 0.7A and I certainly wouldn't trust the BC-700 even if it could do it. 

Cliff notes:
Will the BC-700 suffice...yes.
Is the C9000 better suited...yes (IMHO).

-DF


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## Wrend (Aug 31, 2011)

llmercll said:


> ...Not being able to charge at 1000mA isn't a big deal right? I thought the lower the charge rate the "healthier" it is for the cell anyway?...


 
There are a lot of different factors involved. Eneloops have pretty low internal resistance as far is NiMH AA and AAA cells go. Sanyo recommends charging them at rates up to 0.5C/h (about 1000mA for the AAs, which is the default charge rate on the C9000; "plug and play" capable.) The main thing is that you don't want to overcharge at these higher rates, and the charge termination on the C9000 is on the conservative side for the AAs. Not so much for the AAAs, but still reasonable based on my testing and opinion. You'll _probably_ want to charge AAAs at a lower rate than 1000mA, of course. I charge my AAA Eneloops at 400mA.

The older firmware versions of the C9000 would occasionally miss voltage peak drop detection (-ΔV) for termination with charge rates less than 0.33C/h, which where more likely to be missed because the cells wouldn't heat up enough during charging (hence their recommendation to not charge at a lower rate than that). This isn't really much of an issue now though, since they updated the firmware on newer models.


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## Mr Happy (Aug 31, 2011)

llmercll said:


> I thought the lower the charge rate the "healthier" it is for the cell anyway?


Why, oh why, does everyone seem to think this?

The correct answer is like it was in the story of the three bears, somewhere in the middle, not too low, not too high, but "just right". It turns out that "just right" for an AA sized Eneloop and most AA batteries is around 1000 mA. Now 700 mA will do if you want to go lower, and 1600 mA will do if you want to go higher--this is not an exact science.

But go too low and you will risk missed terminations, overcharging and battery damage. Go too high and you will risk overheating, maybe excess internal pressure and venting, again with possible battery damage.

So follow the middle road, keep your charging current "just right", and be happy!


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## llmercll (Sep 3, 2011)

Thanks for clarifying that Mr Happy =)

What is the ideal charge rate for AAA's? Any idea what rate the stock eneloop charger charges at for AA/AAA?

I'm also wondering if the Maha has a different "default" charge rate for AAA's, as if I understand correctly they are ideal to be charged at slightly less mAh than AA's.

thanks!


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## Mr Happy (Sep 3, 2011)

The ideal charge rate for AAAs is about 400-600 mA. One point where the C9000 is weak is that it uses the same default charge rate of 1000 mA for AAA cells as for AA cells. Using 1000 mA will not be terrible, but it is best to manually drop the charge rate to about 500 mA.

Most of the bundled Eneloop chargers use quite low charging currents, like for instance 360 mA for AA and 150 mA for AAA. This is lower than most would recommend, but those chargers seem to have special electronics so they are able to work successfully. I think it would be best to use them only for Eneloops though.


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## Wrend (Sep 3, 2011)

It also depends on the charger and how it terminates for the specific kinds of cells.

On the current firmware version of the C9000, for Eneloops, I prefer 400mA for the AAAs and the default 1000mA for AAs (as I previously mentioned), because they are within the recommended charge rates of both Sanyo and Maha, and because I don't like my cells getting more than just a little warm while they charge. These rates might not be preferable on other chargers.


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## llmercll (Sep 8, 2011)

Thanks for the help guys =)

It's really a shame the eneloop charger doesn't have single channel charging, I'm pretty content with it besides for that one issue. It's interesting that it charges at such a very low rate though, I wonder exactly how that works. It's considerably lower than what's recommended.

The overall consensus is that the Maha is the way to go, it's just that I'm so frugal haha. I'd probably be glad I chose it in the long run though...


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## The_Driver (Sep 8, 2011)

Also check out the Maha MH-C801D and the Maha MH-C808M. They both charge AAs with either 2A or 1A and have 8 individual channels.


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## tony22 (Sep 9, 2011)

Wrend said:


> The older firmware versions of the C9000 would occasionally miss voltage peak drop detection (-ΔV) for termination with charge rates less than 0.33C/h, which where more likely to be missed because the cells wouldn't heat up enough during charging (hence their recommendation to not charge at a lower rate than that). This isn't really much of an issue now though, since they updated the firmware on newer models.



Wrend, is there a place where one can find out which FW versions work correctly for this and which do not?


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## Valmet62 (Sep 9, 2011)

*Another option*

I agree with llmercll, the La Crosse Technology BC-700 Alpha Power Battery Charger is a good option and priced around 30.00.

Valmet62


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## Battery Guy (Sep 9, 2011)

Mr Happy said:


> Why, oh why, does everyone seem to think this?
> 
> The correct answer is like it was in the story of the three bears, somewhere in the middle, not too low, not too high, but "just right". I turns out that "just right" for an AA sized Eneloop and most AA batteries is around 1000 mA. Now 700 mA will do if you want to go lower, and 1600 mA will do if you want to go higher--this is not an exact science.
> 
> ...


 
Beautifully stated! :thumbsup:


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## Bobby_C (Sep 9, 2011)

La Crosse also make a BC-900 and BC-1000. They're almost identical but the BC-1000 has some extra circuitry to prevent overheating. There's some good reviews on Amazon.com for these chargers.


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## 45/70 (Sep 9, 2011)

Battery Guy said:


> > Originally Posted by *Mr Happy*
> >
> >
> > Why, oh why, does everyone seem to think this?
> ...



I think this goes back to the NiCd days when nearly all consumer level chargers were designed to charge at a 14-16hr rate, similar to a forming charge (0.1C). This charge rate was chosen because generally, at this slow rate, no harm would be inflicted to cells of slightly different capacities.

Back then the cost of the components necessary to make a charger that could charge individual cells faster, was prohibitive. There were some, but due to the increased cost, the general consumer most likely wouldn't have purchased them. Also, most faster rate chargers at that time were setup for specific "packs" of cells arranged in series, not random individual cells. This way the design could be simplified and the risk of overcharging/undercharging, could be more easily handled.

Anyway, since this period lasted for so long, many came to the conclusion that slow charging was "the way" to charge cells, and summarized that it must be better for them. I don't think they realized the actual reason why the 14-16hr rate was chosen, for mainstream chargers of the day.

Dave


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## Battery Guy (Sep 10, 2011)

If it was possible to know the exact state of charge of a NiCd or NiMH, then I would argue that the best way to charge a cell would be to charge at a very low rate (C/10 or even C/20) until it was at 95-98% SOC. However, since this is not really practical for us hobbyists, the best option is to follow Mr. Happy's recommendations above.


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## llmercll (Sep 10, 2011)

The C9000 charges at 1000mAh, but, as it's nearly full, drops to a much lower rate to "finish the job". I can't remember where I read that, but is it true? Isn't that a bad thing since somewhere around 1000mAh is ideal (speaking of AA's anyway)?

thanks for the replies I'm learning a lot and appreciate the suggestions =)


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## Mr Happy (Sep 10, 2011)

llmercll said:


> The C9000 charges at 1000mAh, but, as it's nearly full, drops to a much lower rate to "finish the job". I can't remember where I read that, but is it true? Isn't that a bad thing since somewhere around 1000mAh is ideal (speaking of AA's anyway)?


Try a visual image of something you may have direct experience of: have you ever tried to fill a bottle with water under the tap in the sink? If you have done so, think about what happens. You start out with a strong gush of water and the bottle fills up quickly. But when the bottle is nearly full the water starts overflowing, so you shut the tap off. What happens? When everything settles down the bottle is only 3/4 full. So you turn the tap on again at a trickle to finish filling the bottle to the top.

Well something similar happens with NiMH batteries. When they are empty, they can absorb electricity at a fast rate, so you can start charging them fast. But when they are nearly full, the electricity "overflows"--some of the electricity gets turned into heat and is not absorbed by the battery. To compensate for this you need to turn down the charge rate and finish the charge off slowly. Without getting too much into technical details, this is what the C9000 does. 

The C9000 actually uses a very conservative method of charging. It favors cool batteries over maximum charge, so the top-off charging period is necessary to get the batteries as fully charged as possible. But unless you are really fussy, this doesn't actually matter very much. If you let a charged battery sit around for a week or two, that last little bit of top-off charge will tend to evaporate away and you won't benefit from it.


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## Wrend (Sep 10, 2011)

llmercll said:


> The C9000 charges at 1000mAh, but, as it's nearly full, drops to a much lower rate to "finish the job". I can't remember where I read that, but is it true? Isn't that a bad thing since somewhere around 1000mAh is ideal (speaking of AA's anyway)?
> 
> thanks for the replies I'm learning a lot and appreciate the suggestions =)



It charges the cells until it terminates the charge and displays "done," then it starts trickle charging the cells for a couple hours to top them off, and then goes into an even slower charge rate to float charge the cells.

You don't want to charge the cells as fast when they're full or nearly full because it isn't good for them. A relatively short timed charge at a rate of 0.1C/h or less won't do significant damage to the cells once they're full or nearly full.


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## joeparker54 (Sep 10, 2011)

llmercll said:


> The C9000 charges at 1000mAh, but, as it's nearly full, drops to a much lower rate to "finish the job". I can't remember where I read that, but is it true? Isn't that a bad thing since somewhere around 1000mAh is ideal (speaking of AA's anyway)?
> 
> thanks for the replies I'm learning a lot and appreciate the suggestions =)



200mA @ 1.47V (if the cell doesn't hit -deltaV to signal charge complete before)

I remember reading it here. However I didn't bother to check if it's accurate.

I know many will recommend the c9000, but honestly, I just don't have the need. I have a BC-9009 which I use for refreshing/break-in and keeping track of performance, but I mainly use an assortment of meijer-branded camelion BC-0907s and duracell cef23s. The BC-900(9) and bc-700 are decent chargers, Though not very accurate in reporting capacity. Mine hasn't caught fire or burned, though I don't use it as much as I used to - mainly just for discharging batteries I'm not sure of (though the c9000 can discharge faster and is better equipped to hand the heat). 

Then again, it's a only difference of $8 on amazon....


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## Russel (Sep 10, 2011)

llmercll said:


> The C9000 charges at 1000mAh, but, as it's nearly full, drops to a much lower rate to "finish the job". I can't remember where I read that, but is it true? Isn't that a bad thing since somewhere around 1000mAh is ideal (speaking of AA's anyway)?[...]


 
Low current charging is bad for cells because of missed charge termination, causing overcharging. The MH-C9000 determines the the point of charge termination by several methods, terminating the charge early and finishing the charge with a timed low current charge. Even after the complete charge cycle the MH-C9000 tends to be conservative with the capacity charged into the cells, which is good for the longevity of the cells.


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## llmercll (Sep 22, 2011)

Wow, the BC700 is up to $42 now

http://www.amazon.com/dp/B000RSOV50/?tag=cpf0b6-20

That makes this is an easy decision. Maha here I come =)


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## Johny_be_good (Sep 23, 2011)

The "wizard one" id the better choice in any possible technical comparison between the 2 chargers.
The C9000 has only 2 disadvantages:
1. it is really not a nice charger
2. Its LC Display would not let you sleep, if you would turn it on in your sleeping room.

Otherwise I am still very happy, having it around...

Btw...I got few months ago the MH-C801D, which can charge 8 batteries within 1 hour


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## Wrend (Sep 23, 2011)

> 1. it is really not a nice charger


:thinking:

Care to clarify that at all? I'll agree that it isn't perfect, but it's a lot better than many other chargers.


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## Bobby_C (Sep 23, 2011)

llmercll said:


> Wow, the BC700 is up to $42 now
> 
> http://www.amazon.com/dp/B000RSOV50/?tag=cpf0b6-20
> 
> That makes this is an easy decision. Maha here I come =)


 
You might want to keep checking the price. Amazon tends to change/update prices all the time. 

I just bought the BC1000 and I'm very happy with it. It's $60 but it comes with 4x 2600mAh AA and 4x 1000mAh AAA batteries as well as C and D adapters. The batteries seem to be good quality too, not some cheap add-on.


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## czAtlantis (Sep 24, 2011)

Wrend said:


> :thinking:
> 
> Care to clarify that at all? I'll agree that it isn't perfect, but it's a lot better than many other chargers.


 I think he means it si not visually nice.


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## TyJo (Sep 25, 2011)

Mr Happy said:


> Try a visual image of something you may have direct experience of: have you ever tried to fill a bottle with water under the tap in the sink? If you have done so, think about what happens. You start out with a strong gush of water and the bottle fills up quickly. But when the bottle is nearly full the water starts overflowing, so you shut the tap off. What happens? When everything settles down the bottle is only 3/4 full. So you turn the tap on again at a trickle to finish filling the bottle to the top.
> 
> Well something similar happens with NiMH batteries. When they are empty, they can absorb electricity at a fast rate, so you can start charging them fast. But when they are nearly full, the electricity "overflows"--some of the electricity gets turned into heat and is not absorbed by the battery. To compensate for this you need to turn down the charge rate and finish the charge off slowly. Without getting too much into technical details, this is what the C9000 does.
> 
> The C9000 actually uses a very conservative method of charging. It favors cool batteries over maximum charge, so the top-off charging period is necessary to get the batteries as fully charged as possible. But unless you are really fussy, this doesn't actually matter very much. If you let a charged battery sit around for a week or two, that last little bit of top-off charge will tend to evaporate away and you won't benefit from it.


I'm no expert but that is the best analogy I have seen on CPF (or anywhere). Also, I love my Eneloops and my Maha C9000.


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## Bobby_C (Sep 26, 2011)

llmercll said:


> Wow, the BC700 is up to $42 now
> 
> http://www.amazon.com/dp/B000RSOV50/?tag=cpf0b6-20
> 
> That makes this is an easy decision. Maha here I come =)


 

It's down to $35 today but I just found Thomas Distributing has it for $28


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## llmercll (Sep 26, 2011)

One more question before I purchase the C9000. Does Maha have any "publicly known" plans to release an updated model of this charger? It's been around awhile, no? It'd be a shame if I bought this when an improved model is just around the corner.

thanks for all the help!


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## Mr Happy (Sep 26, 2011)

llmercll said:


> One more question before I purchase the C9000. Does Maha have any "publicly known" plans to release an updated model of this charger? It's been around awhile, no? It'd be a shame if I bought this when an improved model is just around the corner.



Look up "Osborne effect" and see why you are unlikely to find the answer to that question


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## davecroft (Sep 27, 2011)

I'm in UK and looking to buy my first 'proper' charger - there is a model on Amazon UK (see link below) called the Technoline BL-700 which looks similar to the BC-700. Can anyone confirm if it is the same type? Thanks

http://www.amazon.co.uk/dp/B003S4JQS2/

EDIT: Just done some more digging on the web and it looks like it is the same charger. There are a few different brand names for it.


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## Tsportmat (Sep 27, 2011)

davecroft said:


> I'm in UK and looking to buy my first 'proper' charger - there is a model on Amazon UK (see link below) called the Technoline BL-700 which looks similar to the BC-700. Can anyone confirm if it is the same type? Thanks
> 
> http://www.amazon.co.uk/dp/B003S4JQS2/
> 
> EDIT: Just done some more digging on the web and it looks like it is the same charger. There are a few different brand names for it.



I have a Technoline BL-700 - I think it's the EU version of La Crosse; the specs are the same but I'm not 100% if they're made by the same company. Either way, it seems to work fine...


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## Wrend (Sep 27, 2011)

llmercll said:


> One more question before I purchase the C9000. Does Maha have any "publicly known" plans to release an updated model of this charger? It's been around awhile, no? It'd be a shame if I bought this when an improved model is just around the corner.
> 
> thanks for all the help!



Not that I know of. At this point I think they'd be more likely to come out with a newer model charger than do too many more significant updates to the C9000.

I don't think it's been significantly updated for a few years now.


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## hwc (Sep 28, 2011)

I'm on my fourth Maha charger going back many, many years now. This one is the 8-cell 801. It's been fantastic. I love being able to charge up to eight batteries at once. That's a big help when trying to get everything in the house recharged prior to a storm -- or when you wife needs two sets of camera batteries charged and gives you one hour notice before leaving (not as important with eneloops, but really important with Sanyo 2700s that need to be topped up).

Best feature: independent charging channels. Charge 1 battery, 2 batteries, 5 batteries, completely empty batteries, almost charged batteries, 3aaa and 1aa, doesn't matter.

Only minor quibble: it defaults to a one-hour charge (2000ma for AA, 1000ma for AAA). I'll use that if I'm really in a hurry, but as noted above that's a pretty aggressive charge rate and, as a general rule, I prefer charging a little slower. So I have to press the SOFT CHARGE button after insterting the first battery for ideal two-hour charging (1000ma AA, 500ma AAA). I wish this were backwards and it defaulted to the slower charger, but that's a minor issue.

I wouldn't mind the option of a fast discharge and a slow charge when conditioning, but it's not a big deal. If I'm around when the charge cycle starts, I just yank the batteries, put them back in, and do the two hour charge.

I believe the newer less expensive version of the 8-cell charger has slower charge times across the board. That would be fine.


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## llmercll (Sep 28, 2011)

I've ordered it and should be receiving it soon. Purchased from amazon through Thomas Distributing, and comes with a free case =)

Can't wait!


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## B0wz3r (Sep 28, 2011)

I received my C9000 from Thomas Distributing today. I have a batch of duraloops in it right now on a break-in cycle.

This thread has been tremendously helpful... thanks all of you for all the good information and advice.


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## radellaf (Sep 30, 2011)

If all you want is single eneloop charging, why not get one of the reliable and cheap Sanyo brand chargers that can do that? I'm fond of both their 2-cell USB and direct wall-mounted plug-in chargers, but they have a 4 cell one that has individual cell monitoring as well. The C9000 is a lot of fun, but if all I have is one or two regular in-use cells to charge, I just use the Sanyo chargers.

I'd agree that the slower-is-better idea comes from the NiCd days. Typical consumer AA NiCds in the 1980s were not specified for a fast charge. "8-hour" and less "fast charge" cells came along later. Whether it was actually bad to charge 1980s 600mAh NiCd AAs at 300mA instead of 60mA, I have no idea. Nobody made a known-to-the-public charger that would do that. Some early fast-charge consumer chargers were absolutely awful. The Maha MH-401FS was the first one I remember being easily available that did a trustworthy job (i.e. per-cell monitoring instead of pairs), and even it was known to reach higher-than-ideal temperatures at the fast (1000mA) rate.
By the time NiMH became available in retail outlets, it was kind of the same thing we have now. Even if the cells were decent, quite often the fast chargers were not. It's better to have a crappy C/10 charger than a crappy fast charger. Early on, though, either kind of charger would kill batteries. The difference now is that NiMH can now take some (indefinite?) overcharge without keeling over immediately, which wasn't the case in 1995.

The whole thing about unreliable delta-V below C/2-C/3 is something I never heard of until 6-7 years ago. In 1996 I was working on "cutting edge" charge termination for NiMH cellular phone batteries and that advice was nowhere to be heard.

What still surprises me is that charge _efficiency_ is higher at faster rates, for NiMH at least. I don't know about NiCd.


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## Mr Happy (Sep 30, 2011)

radellaf said:


> What still surprises me is that charge _efficiency_ is higher at faster rates, for NiMH at least.


I don't think it is.

Charging and discharging of a cell is a chemically and thermodynamically reversible process. When you discharge a cell slowly you get more energy out of it and higher capacity as the effects of internal resistance and other rate limiting factors are reduced. In essence, a slow discharge more closely approximates a truly reversible process and this has a higher efficiency. Since the charge/discharge process is reversible, the same factors will apply in both directions. Charging slowly will also be more efficient than charging rapidly for exactly the same reasons.

It is possible to test this with a C9000 by charging and discharging an Eneloop at different rates. You should find that charging an Eneloop at 100 or 200 mA is more efficient than charging at 1000 mA, as long as you charge the cell up to the same state of charge (e.g. same open circuit voltage) in each case so you are comparing like with like.

Where low rate charging _seems_ to be inefficient is when the charger applies a significant overcharge before termination. But this is not a measure of inefficiency in the cell, it is a measure of the charger wasting energy.


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## llmercll (Oct 1, 2011)

Got my C9000 today!!

I haven't plugged it in yet but am impressed with it's size and build quality. I think I'm going to appreciate spending a little extra for the additional features too.

Now, I have about 16 AA's and 8 AAA's that I've been using for a little over a year, and charging with the eneloop charger, in pairs. Do you think I should do the "break in" mode on ALL of them and then "match" them based on capacity?

thanks!


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## samgab (Oct 1, 2011)

llmercll said:


> Got my C9000 today!!
> 
> I haven't plugged it in yet but am impressed with it's size and build quality. I think I'm going to appreciate spending a little extra for the additional features too.
> 
> ...


 
Good choice. If I were you, I would do exactly that. Break them all in, and "match" them up by the capacity. It's exactly what I did with all of my old NiMHs when I first got the C9000. It takes a long time (weeks!) but it's good, because you get a very clear picture of which of your cells are still good, and which are ready for the recycler.


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## llmercll (Oct 1, 2011)

Sounds good. Do you recommend I discharge the cells (@500MA) before the break in?

thanks!


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## Mr Happy (Oct 1, 2011)

llmercll said:


> Got my C9000 today!!
> 
> I haven't plugged it in yet but am impressed with it's size and build quality. I think I'm going to appreciate spending a little extra for the additional features too.
> 
> Now, I have about 16 AA's and 8 AAA's that I've been using for a little over a year, and charging with the eneloop charger, in pairs. Do you think I should do the "break in" mode on ALL of them and then "match" them based on capacity?


I'm going to give you different advice. If you start out right away running break-in cycles you will tie up the charger and you won't get to use it. I suggest you run your batteries through some normal charge, discharge and refresh cycles to get familiar with the charger features and how your cells perform. After you have done that, you might pick out the lower performing cells and run a break-in on them to see if you can improve them.


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## samgab (Oct 1, 2011)

llmercll said:


> Sounds good. Do you recommend I discharge the cells (@500MA) before the break in?
> 
> thanks!


 
I always discharge before breaking in, because the first thing the break-in does is charge at 1/10C for 16 hours. Although it's a low enough rate not to cause any major harm, I still wouldn't want to do that on a half or fully charged cell. 500mA rate is fine. At least if you discharge prior to break-in, you know for sure you're starting with an empty cell.


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## Wrend (Oct 1, 2011)

New Eneloops don't really need to be broken in. It can improve their performance specs a little if they've been in storage for a while, but that won't really matter too much either unless you're using them in higher drain rate applications. That, and they'll improve during normal cycle life a little as well anyway if you're using them regularly.

Eneloops come pre-charged to about 75% of their capacity, and are generally fine to use right out of the packaging. You can top them off if you want too.

I however do discharge and break in my new Eneloops to test their capacity and performance for matching cells in series sets which I maintain the same usage history on. I also have extra sets of cells for each series count so that when the batteries in something get low, I can just grab another set without having to wait for the cells to charge.

I discharge the new Eneloops at 100mA on the C9000, run a break in cycle for 1900mAh on the AAs, 800mAh on the AAAs, adjust the measured capacity results for the average measurement divergences on the different ports of my C9000, measure their relative internal resistance, then group and label them accordingly. I then discharge each set of cells at 100mA before charging them normally, because some of the cells within each set could have been waiting around for a while (months) more than the others during testing. I also keep a log of the capacity and internal resistance performance to reference over the life of the cells.

As I mentioned, for normal charging on the C9000 I charge the AA Eneloops at the default 1000mA and the AAAs at 400mA. So far I haven't had any problems with charge termination and the cells only get just a little warm.


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## radellaf (Oct 3, 2011)

Mr Happy said:


> I don't think it is.
> 
> Charging and discharging of a cell is a chemically and thermodynamically reversible process...



Oh, I agree with what you say, but the tests I did were on a UBA4, not a C9000, so I'm pretty sure the measurements were accurate. It wasn't a huge difference, but it was there. My posts on it, from 2007 probably, may still be available by search. I _think_ I did it by putting a fixed amount like 1Ah into a cell at multiple rates and then doing a discharge. Only one cell, one set of tests, but that's what I saw. I don't have access to that equipment any more, but I'm hoping to have a UBA5 available in a week or so.

The other thing I was testing for is delta-V peak vs. charge rates. IIRC, I came to the conclusion that for my normal use, with good cells, easily detectable peaks showed up at C/5 with no problem. Sure, there's more likely to be a missed termination, but suffice to say I have no worries about using my Eneloop chargers, or setting the C9000 to a ~3 hour 800mA rate for AAs. Assuming proper termination, I imagine the max. temp during the cycle is lower, so that's my rationale. AFAIK, there's no advantage to 1-hour charge vs 3-hour if you're not in a hurry.




Wrend said:


> ...adjust the measured capacity results for the average measurement divergences on the different ports of my C9000, measure their relative internal resistance, then group and label them accordingly.



Dare I ask, how did you measure port differences? Rotating 4 cells through a few times?
How much difference in your Eneloops (at least of the same package/date code)? With all my break-ins within +-40mAh of 1950, I never bothered to match sets. I never did test for resistance though.


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## Wrend (Oct 3, 2011)

> Dare I ask, how did you measure port differences? Rotating 4 cells through a few times?
> How much difference in your Eneloops (at least of the same package/date code)? With all my break-ins within +-40mAh of 1950, I never bothered to match sets. I never did test for resistance though.



It's an ongoing averaging process. I calculate the average capacity variation between the ports from cells in new Eneloop 4-packs during the break in process I do for new cells.

Even though they're from the same pack, the cells will still have some variation, of course, so the more samples, the more accurate the results should be on average (excluding obviously "bad" cells, which I've been fortunate enough not to find yet doing these tests). I've done this for 12 new 4-packs so far since getting my C9000 a few months ago. I plan on doing it for 8 more 4-packs soon.

To get the adjusted cell capacity for the ports, I currently multiply port one's measured capacity by 1.00133394066, port two's by 0.992763752098, port three's by 1.00754037539, and port four's by 0.998475214121. (At most the ports on my C9000 only have a difference of about 1.5% from each other.)

This isn't something the average user will want to bother with. (Just crazy battery enthusiasts.)

:thumbsup:

...

I think cells can sometimes charge somewhat more efficiently at faster rates. There are probably also differences between the LSD NiMH cells and standard NiMH ones. I think this might be because of the temperature of the cells while they're being charged at the different rates, and a change in their internal resistance at these temperatures, or similar.

To put it another way, the cell chemistry might be more active at higher temperatures and therefor more easily charged/discharged.

I haven't tested this specifically myself.


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## samgab (Oct 4, 2011)

What?! Only 11-12 decimal places?


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## budynabuick (Oct 4, 2011)

samgab said:


> What?! Only 11-12 decimal places?



That's what i was thinking LOL I am a battery nut as well! I love this stuff
Keith


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## Wrend (Oct 4, 2011)

samgab said:


> What?! Only 11-12 decimal places?



Yeah, they're really only relevantly accurate to a resolution of 4 decimal places.

:shrug:


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## radellaf (Oct 5, 2011)

I'm not sure I get the method. Do you just have that many eneloops to discharge, that you can calculate it by comparing the overall average with the average for each slot? Or is it that you run break in cycles repeatedly on just a few (like 8 or so) cells? If it's within +-1% then I think I can live with ignoring it, but I vaguely remember hearing that certain models had a slot or two that was much further (>10%) off.

As for charge efficiency, yeah, temperature was the only theory I came up with. That or there's some serious self-discharge that occurs at the same rate regardless of charge current. Or, did I forget to let the cells cool after the charge? I think I did let them cool but it was a long time ago.


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## Wrend (Oct 5, 2011)

The data I used to calculate these values was from 12 new 4-packs of Eneloops (48 cells). I plan to incorporate the results from 8 more new 4-packs (32 cells) before too long to have a larger data base.

I'm basically just comparing the average capacity results of the cells in each specific port with the total average of all of these cells.

The reason I'm only using new 4-cell packs is because the cells within each pack should theoretically be very similar to each other.

But yeah, the differences between the charger ports on my C9000 as far as capacity testing goes should be less than 1.5% based on my results so far. However, the ports do seem to have fairly consistently higher or lower results than each other, even if it is only this small difference.

This consistent behavior was what led me to try and find out the difference between the ports in the first place, and since I had been recording the capacity values of the new cells anyway, it seemed like the most convenient and reliable way to go about it.


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## llmercll (Oct 6, 2011)

I couldn't resist, so started breaking in all my batteries. The charger is great! I don't see how people complain about keystrokes, it's really not that bad. In fact I feel it allows for more control and enjoy it. So far my eneloops are all reading between 1900-2000, which I believe, is good. Almost done with my AA's, then will do AAA. I'm naming them like this

AA1
AA2
AA3 for AA's
etc

AAA1
AAA2 for AAA's
etc

and will of course capacity match them before writing with marker. I currently have sticky notes on each cell =p

Sound good to you guys?

Also, the only other complaint I've heard is that the backlight is too bright, and while it is bright, I'd rather have it the way it is than not have a backlight at all. It would have been nice to include a switch to turn it off/on though. I simply rest the top of a little rectangular tin over the lcd before bed, making sure it isn't restricting airflow. Chances are on, once my cells are broken in, I won't be running it at night anyway. Build quality is wonderful, and the batteries and unit hardly get warm. This is a winner in my book! =)


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## radellaf (Oct 6, 2011)

It's not too hard to open it up and add a resistor to dim the backlight.

I wonder if I couldn't get per-slot correction factors by measuring the current sense elements. Anyone know what they are? Is it an accessible bit of wire or a resistor or something less amenable to measurement, like the Rdson of 4 different FETs (resistance of 4 transistors). I have a meter in the lab that can do precision lo-ohm kelvin measurements. I'd love to know, but I sure don't (in this case at least) have Wrend's kind of patience on this one. I rely on the capacity more for an "oh crap, that cell has bit it" kind of measurement. Less than _+25 or 50mAh on an AA I don't sweat.
I could compare them all to the Bantam, I suppose. That might be easier, perhaps, maybe...


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## ALW248 (Oct 22, 2011)

Battery Guy said:


> If it was possible to know the exact state of charge of a NiCd or NiMH, then I would argue that the best way to charge a cell would be to charge at a very low rate (C/10 or even C/20) until it was at 95-98% SOC.



I have an old charger from 1990, Eveready FCC2. It charges at 100mA. With 500mAh NiCd, it was C/5. It was called "Fast Charger", FCC2.

With 2000mAh NiMH, it is C/20. But it terminates at C/20! 

At the beginning, with 100mA, the batteries are completely cool. But the charger is warm outputing 4x100mA. 

When the batteries are full, they warm up. Then the charger terminates. Both the batteries and the charger cool down.

I have link to the charger on my page:
http://stereo.50webs.com/


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## Wrend (Oct 22, 2011)

What temperature does it terminate the charge at, or if it uses a change in temperature, what is the sample rate and change in degrees that it uses?

Or maybe it measures ambient temperature and cell temperature independently and terminates the charge based on the difference between them?


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## leeholaaho (Oct 22, 2011)

I have this one, it is not fancy fancy, but it does the job.
I like this charger, the reviews are positive and the price reasonable
I have used it for about a year with no problems.
The 12 volt feature is a plus.


http://www.batteryjunction.com/8800.html


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## ALW248 (Oct 25, 2011)

Wrend said:


> What temperature does it terminate the charge at, or if it uses a change in temperature, what is the sample rate and change in degrees that it uses? Or maybe it measures ambient temperature and cell temperature independently and terminates the charge based on the difference between them?



My guess is that FCC2 does not have temperature sensor.

The termination temperature of the 100mA FCC2 is much cooler than my 1000mA Sony BCG-34HRM.


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## bruintennis (Jan 7, 2012)

I'm so glad I found CPF. What a great resource for all flashlights and rechargeable batteries! Thanks guys.


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## bruintennis (Jan 11, 2012)

Yay! My Maha MH-C9000 charger/analyzer arrived by UPS today! Time to start charging my eneloops. Using this charger compared to what I was using (Lenmar Pro99) is like going from a dark cave into the sunlight for the first time! Glad I bought the charger.


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