Duraloop / Eneloop AA battery abuse question

[Techjunkie]

The Sanyo Eneloop AA and Duraloop (white topped Japanese made Duracell Prechaged) AA are known to be capable of sustaining some pretty high currents, but my question is, at what cost?

I have some pretty big plans for my Duraloops, but want to know if constantly running them at 4A+ draw will damage them / cause them to build up internal resistance / shorten their service life in rapid fashion.

What about sustained 2.1A draw?

 

[TakeTheActive]

The Sanyo Eneloop AA and Duraloop (white topped Japanese made Duracell Prechaged) AA are known to be capable of sustaining some pretty high currents, but my question is, at what cost?

...want to know if constantly running them at 4A+ draw will damage them...

NiMh AA Powered LED light - Current Draw​

 

[Techjunkie]

NiMh AA Powered LED light - Current Draw​

Thanks, but that particular thread only has one reply and the reply only addresses reduced capacity at higher discharge rates (not capacity loss).

My question is about long term effects (cell damage) of high discharge rates (not deep discharge) on these particular cells and what "high" (damaging) rates actually are for these cells.

The top pics list that you keep is an awesome resource, thanks for that. If there's a thread linked there that describes what discharge rates are damaging to Eneloops, I missed it. Otherwise my question still stands.

I'll rephrase it for clarity:

What discharge rate is considered to be damaging to Eneloop AA cells?

 

[TakeTheActive]

Thanks, but that particular thread only has one reply and the reply only addresses reduced capacity at higher discharge rates (not capacity loss).

My question is about long term effects (cell damage) of high discharge rates (not deep discharge) on these particular cells and what "high" (damaging) rates actually are for these cells...

...I'll rephrase it for clarity:

What discharge rate is considered to be damaging to Eneloop AA cells?

Sorry, that topic hasn't got my interest. How about: Ansmann 2850 AA Cells Performance Results!

CPF 'Batteries Included' Archive SEARCHes for Mr Happy and/or SilverFox should help in your quest until one of them replies.

...The top pics list that you keep is an awesome resource, thanks for that...

Thank you!

 

[Mr Happy]

The top pics list that you keep is an awesome resource, thanks for that. If there's a thread linked there that describes what discharge rates are damaging to Eneloops, I missed it. Otherwise my question still stands.

I'll rephrase it for clarity:

What discharge rate is considered to be damaging to Eneloop AA cells?

I'm afraid that I don't think we know the answer to that question. Cells do not so much suffer damage as experience wear as they make inexorable progress towards the end of their service life.

The service life of an Eneloop is typically several hundred charge/discharge cycles. This could be more under light use and less under stressful use. I have not seen a chart showing service life correlated with typical discharge rates.

I would suggest that if the cell does not get excessively warm during the discharge then it is handling the load OK. Various people have built applications with discharge rates in the order of 4-5 A. That would seem to be a sensible and practical limit given the voltage/load characteristics of Eneloops.

 

[Bullzeyebill]

Various people have built applications with discharge rates in the order of 4-5 A. That would seem to be a sensible and practical limit given the voltage/load characteristics of Eneloops.

See the latest USL thread. So far 11 Eneloops are doing fine at 8+amp draw in Codeman's USL, set up by js.

Bill

 

[Mr Happy]

See the latest USL thread. So far 11 Eneloops are doing fine at 8+amp draw in Codeman's USL, set up by js.

Wow. I don't get much more than 10 amps with a dead short

 

[Techjunkie]

Sounds like everything's coming up roses. Thanks guys.

 

[Bright+]

When abused a few things will happen.

1.) The internal resistance will gradually build up and increase voltage drop for a given current draw.
2.) Capacity will decrease
3.) Self discharge will increase

When cells can no longer provide satisfactory performance for your application, then its considered end of life.

 

[Techjunkie]

When abused a few things will happen.

1.) The internal resistance will gradually build up and increase voltage drop for a given current draw.
2.) Capacity will decrease
3.) Self discharge will increase

When cells can no longer provide satisfactory performance for your application, then its considered end of life.

Exactly. So the question is, what constitues abuse for Eneloop AA? Pesumably, one form of abuse would be sustained current draw high enough to cause internal temperature to rise enough to cause the effects described above...and that magic number is?

No one seems to know the magic number. I will assume for the moment that the number is above 4.2A and carry on my merry way no longer caring :^P

 

[SilverFox]

Hello Techjunkie,

NiMh cells achieve longer cycle life when they are subjected to discharge currents of 1C or less.

They are usually rated for 2C loads as a general maximum.

More specifically, you can test your cells and see what load causes the mid point voltage to drop below 1.2 volts. The mid point is half way through the discharge. For example if your discharge yields a capacity of 2000 mAh, you would go back to where the discharge was at 1000 mAh and check the voltage there.

As long as your mid point voltage is 1.2 volts or higher, you should get good cycle life from your cells. You can drive them harder, but that results in reduced overall cycle life.

Tom

 

[UserName]

Exactly. So the question is, what constitues abuse for Eneloop AA?

They have a 5 year warranty. Push it to the limit, and let them replace it if it fails.

 

[Apollo Cree]

You should also consider what degraded performance means to you. If you get 100 charge cycles instead of 500, do you really care if you get the performance you want? How about 50 cycles?

If you get, for instance, 80% capacity after 50 cycles and throw it away, are you still happy?