Looking for charger for AA - specifically Eneloop XX style batteries

Hi,

I'm looking for a good charger for Eneloop batteries, specifically the XX style (Amazon's re-branded versions included). I've read a lot of HKJ's reviews, and haven't been able to pick one that is best for my needs. I'm looking for a charger that will be best for my situation:

1) I'm not concerned about absolute fastest charging, I prefer more cycles. If I can get faster charging without notable decreases in cycle count, that's wonderful. I wouldn't mind a 10% decrease in cycle count to charge 50% faster, but would mind a 50% cycle count decrease to charge 10% faster. I'm looking for a good compromise.
2) I'd like to get close to maximum capacity out of batteries without worrying about pushing them too far and decreasing cycle count. See above re: compromise.
3) I'd like something I can put the batteries in and not worry about the trickle charge decreasing cycle count even if I leave them on after 'full'; I would be putting batteries in the charger at night and wouldn't be removing them until the morning in most cases. Some of the charger reviews I've read have indicated you need to pull the batteries at the end of the charge cycle or the trickle charge will end up decreasing life spam.
4) Having information regarding the battery health (mAh input/etc) would be very useful. I'd like to know when my cells are degrading, as they are used for remote operation and having a bad cell would not be ideal.
5) I'd love the break-in cycle functionality, as well as refresh functionality, as it does seem to have at least some tangible benefit from what I've read here. This isn't a deal-breaker, but would be nice.

I'm making a new thread with the specifics of my desired ideal state as many of the threads I read were much more generic. With people like HKJ that are so knowledgeable about pros/cons of each charger, I think I will get a much better solution than if I tried to reason through all the reviews and try to determine the best fit on my own, as I have very little experience with NiMh batteries and chargers.

Thank you for any input you might have!

Hello Ormandj,

Welcome to CPF.

The Maha C-9000 looks like it will do everything you are looking for.

Tom

SilverFox said:

Hello Ormandj,

Welcome to CPF.

The Maha C-9000 looks like it will do everything you are looking for.

Tom

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Hi Tom,

I've read a lot of good things and it seems to be quite commonly suggested here. I appreciate your input!

After charging, the C9000 does do a top off and then an indefinite trickle charge afterwards - it's not something that I would be too worried about though if you're only leaving your batteries in the charger overnight.

Keep in mind that the Eneloop XX cells are only rated for about a quarter of the number of cycles as the latest regular Eneloops. Depending on your use, that may not matter and even if it does, that might be acceptable if you need the extra capacity.

What sort of device are you using the cells in? I'm assuming that it uses only low currents?

I would thoroughly recommend either the BL-700 or BC-1000 from Techno line (possibly branded La Crosse outside the UK). I use both for all of my critical AA and AAA charging.

If you need point 5 (break-in), only c9000 style chargers offer this, point 4 is offered by both c9000 & Technoline/Lacrosse style chargers. Thus you really have a selection among 5-6 chargers to pick. If you are willing to step back on points 4 & 5, there are a lot of chargers at lower cost to pick from. As long as they are smart ones with individual channels you'll be fine but don't resort to very low charging currents i.e. 200mA due to the increased risk of missed terminations. Point 3 is not that bad to worry about, unless if the charger provides a high enough trickle charge current, I can say 10-20 mA is the maximum acceptable trickle charge rate - beyond that I'd worry. A few hours trickle charge on a regular basis will reduce the battery life a bit but it doesn't compare to the damage done by overcharging thus it shouldn't bother you. If however you forget the batteries for 2-3 days, then this will have quite an impact.

Models to consider for points 4 & 5:
Maha MC9000
AccuPower IQ328
LaCross BC700/BC1000
BM200 (replaced by Opus BT-2000)
SkyRC NC2500

I think there are a couple other chargers of the same logic but I can't recall their names right now.

Power Me Up said:

What sort of device are you using the cells in? I'm assuming that it uses only low currents?

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Elecraft KX3 (~150-190 mA RX, 750 mA - 2.1 A TX), runs on 8xAA. These are backup, I'd be running off an external lithium pack most of the time. That's why I'm willing to sacrifice some cycles for higher capacity (and definitely need the LSD style batteries). I won't be using them terribly frequently, but when I do, I'd like them to have as much capacity as possible. Cycle count is only important from the standpoint that I don't want to buy $40 worth of batteries to have them fail after using them 50 times. If I get 250+ cycles out of them, I'll be ok.

apagogeas said:

If you need point 5 (break-in), only c9000 style chargers offer this, point 4 is offered by both c9000 & Technoline/Lacrosse style chargers. Thus you really have a selection among 5-6 chargers to pick. If you are willing to step back on points 4 & 5, there are a lot of chargers at lower cost to pick from. As long as they are smart ones with individual channels you'll be fine but don't resort to very low charging currents i.e. 200mA due to the increased risk of missed terminations. Point 3 is not that bad to worry about, unless if the charger provides a high enough trickle charge current, I can say 10-20 mA is the maximum acceptable trickle charge rate - beyond that I'd worry. A few hours trickle charge on a regular basis will reduce the battery life a bit but it doesn't compare to the damage done by overcharging thus it shouldn't bother you. If however you forget the batteries for 2-3 days, then this will have quite an impact.

Models to consider for points 4 & 5:
Maha MC9000
AccuPower IQ328
LaCross BC700/BC1000
BM200 (replaced by Opus BT-2000)
SkyRC NC2500

I think there are a couple other chargers of the same logic but I can't recall their names right now.

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5 I could go either way on, but 4 is important to me. Thank you for the info re: trickle charge rate.

You want a charger than can do 1000mA charge rate.
Termination may be missed if you only charge at 700mA

If mah ( capacity ) readings is of importance , you should know SkyRC NC2500 is reported to be very inaccurate by more than one member , whereas Maha MC9000 & Opus BT-2000 should be almost spot on according to another test.

ormandj said:

Elecraft KX3 (~150-190 mA RX, 750 mA - 2.1 A TX), runs on 8xAA. These are backup, I'd be running off an external lithium pack most of the time. That's why I'm willing to sacrifice some cycles for higher capacity (and definitely need the LSD style batteries). I won't be using them terribly frequently, but when I do, I'd like them to have as much capacity as possible. Cycle count is only important from the standpoint that I don't want to buy $40 worth of batteries to have them fail after using them 50 times. If I get 250+ cycles out of them, I'll be ok.

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I'm currently in the process of doing cycle life testing on Eneloop XX cells at the moment and from what I've seen so far, I'd be quite surprised if you managed to get 250 full cycles out of them. Keep in mind that the cycle life testing that manufacturers use for rating their cells is based on mostly incomplete charge/discharge cycles, so it's to be expected that you'll get less cycles when the cells are being fully cycled.

2.1A is a pretty decent load for AA batteries - Eneloop XX cells will handle it fine when they're still relatively new, but as with all NiMH cells (and batteries in general) their internal resistance will increase as they age. At some point, you will find that the internal resistance gets so high that they're no longer able to handle a 2.1A load and the device won't work properly when it tries to pull such current. At that point, the C9000 will probably be quite happy charging your batteries still and will still give you decent capacity readings. The device will also work fine most of the time when it's only drawing small amounts of current - it will only be when it tries to pull the higher current that you'll start to have problems.

I'd suggest that you keep an eye on the internal resistance of your batteries and replace them when they're getting above about 100 milliohms (even that might be a bit high if the device is voltage sensitive) It is possible to work out the IR from the initial voltage check from the C9000, but you need to know how to do it - it's a little bit tricky. The SkyRC NC2500 has the ability to give you IR readings, but I wouldn't trust it to give you accurate capacity readings - I had one briefly and there were significant differences between the slots.

Another alternative is the UltraSmartCharger (note that I'm the firmware developer for it, so keep that in mind) - it automatically logs the IR of cells as they're charging and also gives you an initial IR reading when starting a discharge. You can also adjust the parameters for the UltraSmartCharger so that it automatically rejects cells that have started to develop high IR.

Is there a way to measure IR of a battery using a DMM? A simple resistance check results in 0 ohms (or infinite for some reason, if I reverse the leads). But I figure it's more complicated than that.

Look here: http://lygte-info.dk/info/Internal impedance UK.html

Thank you everyone, I ended up going with the Maha MC9000. Sounds like it is tried and true, and as long as I don't let batteries sit on it too long after it finishes charging, it'll be fine.

Is it worth buying Eneloops (including the XX) if you only have a dumb charger or should you just use "dumb batteries" and wait until you can get the Eneloops and the smart charger at the same time?

Edit: By the way, and pardon the newb question, but do the 2500mA XX batteries give you a brighter output on the light than the 2000mA Eneloops or just longer runtime?

Thanks.

LaCross BC700 did alright for me.

Treeguy said:

Is it worth buying Eneloops (including the XX) if you only have a dumb charger or should you just use "dumb batteries" and wait until you can get the Eneloops and the smart charger at the same time?

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In either case, get a smart charger asap. I wouldn't personally waste my money on Eneloop XX if you're using a dumb charger on them, since it will likely dramatically shorten their life span. I might buy the regular Eneloops, since they're much cheaper and are rated for many more cycles, so they might stand up to abuse better.

Edit: By the way, and pardon the newb question, but do the 2500mA XX batteries give you a brighter output on the light than the 2000mA Eneloops or just longer runtime?

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Longer run time.

I hear ya. I just wanted to avoid spending $50 on a smart charger if it wasn't necessary.

Thanks.

Treeguy said:

I hear ya. I just wanted to avoid spending $50 on a smart charger if it wasn't necessary.

Thanks.

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$50? What are you talking about. The last analyzing NiMH charger I reviewed is below $20 (See my website). I would expect that you can get a non-analyzing smart charger even cheaper.

HKJ said:

$50? What are you talking about.

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Hey, be nice. I`m very sensitive.

I know chainsaws, not chargers.

HKJ said:

The last analyzing NiMH charger I reviewed is below $20 (See my website). I would expect that you can get a non-analyzing smart charger even cheaper.

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Amazon in Canada has the La Crosse 500 at $40 and the 1000 at $60, so I split the difference. La Crosse and Maha are two names I see thrown around by people who know more than me - which is pretty much everyone - so I figured I should go with what they say.