Optimum charging rates for AA batteries

[the_eleven]

Greetings to the CPF!

I have just purchased a MAHA C9000 and some Delkin 2900mAh AA's for use in a Petzl MYO RXP. This is used daily in my work, and is on intermittently; 2 hours out of an 8 hour day.

After doing one break-in cycle, I am ready to charge, but am uncertain which charging rate would be best for this application.

A summary reading of posts returned after a search on "charging rates", did not yield a wealth of info. One post advised 0.5C to 1.0C; but there is some info that a higher charge rate works as well.

Could someone answer this question directly, or point me in the direction of more comprehensive info on this subject?

Thanks!

 

[Ragiska]

One post advised 0.5C to 1.0C; but there is some info that a higher charge rate works as well.

there's your answer. 1C is the "higher" rate that all battery manufacturers recommend.

 

[Mr Happy]

Greetings and welcome to CPF! :welcome:

I suggest you use the C9000 default charging rate of 1000 mA for your batteries.

Note that 0.5C to 1.0C refers to the capacity of the batteries. So if your cells were truly 2900 mAh then 1.0C would be a charging rate of 2900 mA, or 2.9 amps. However, high capacity cells have thinner and more fragile internals and they do not take well to high charging rates like that, it will wear them out more quickly.

For most AA cells of any capacity a charging rate of 1000 mA or 1 amp is a good rate to pick, balancing speed and reliability.

Out of interest, what capacity measurements did you get from your break-in cycle?

 

[the_eleven]

Thanks for the quick responses. Will use the default setting.

Re: capacity of this battery: I was not paying close attention. Is there a way to get a quick reading of the capacity using the MC9000?

Otherwise, I will charge these up and see what they give...

 

[Mr Happy]

When the break-in cycle finishes the cells are fully charged and ready for use. (A break-in cycle consists of charge-discharge-charge again.)

When the break-in cycle is finished the display shows the measured capacity for each cell. Most people take note of the numbers before removing the cells from the slots, since one of the main reasons for doing a break-in cycle is to analyze the cells and see how they measure up.

If you have removed the cells there is no way now to get those numbers back. You could if you wish (and are patient) discharge the cells down to empty at 500 mA and then run another break-in cycle on them.

Otherwise you will need to run a refresh/analyze cycle to get the capacity, but this gives a lower and less accurate measurement (although it is a measurement more typical of real life usage).

 

[the_eleven]

Ah!

Just started a break-in cycle on another 4 of the Delkin 2900 mAh AA's. This time, will pay attention to the capacity readings at the end of the cycle, and post them here...

 

[fkoenig]

Hello! I just purchased the C9000 as well and ran through the 1st break-in cycle of the AA's that came with the charger (2700 mah). The charger cycled (per my wife looking at the charger) of 2550 mah in each cell. So my question here, is this saying the break-in cycle is finished? Would it be OK to tell her to pull the plug and leave the batteries in until Thursday (today is Monday) until I get home to take them out? Thanks!

 

[Mr Happy]

Hello! I just purchased the C9000 as well and ran through the 1st break-in cycle of the AA's that came with the charger (2700 mah). The charger cycled (per my wife looking at the charger) of 2550 mah in each cell. So my question here, is this saying the break-in cycle is finished? Would it be OK to tell her to pull the plug and leave the batteries in until Thursday (today is Monday) until I get home to take them out? Thanks!

There's really no need to make the same post in two different places. I just answered your post in the other thread.

 

[the_eleven]

.....Out of interest, what capacity measurements did you get from your break-in cycle?

Well, did the break-in cycle on 4 batteries, and at the end of the cycle the charger said 2318, 2301, 2325, and 2336.

Does this seem right for "2900" mAh batteries?

 

[MarioJP]

Well, did the break-in cycle on 4 batteries, and at the end of the cycle the charger said 2318, 2301, 2325, and 2336.

Does this seem right for "2900" mAh batteries?

Whoah why do these manufactures label a cell with a certain capacity that is truly not???. I guess certain things in life can't be explained. Unless these cells really needs to be cycled many times??.

What is the true highest capacity a NiMh AA cell can go?.

AAA has hit a dead end ranging from 800-1000mAh.

 

[the_eleven]

Perhaps I could try:

Discharge mode then do break-in again?

Call Thomas Distributing and rant?

Use them and not worry about it?

 

[core]

Perhaps I could try:
Discharge mode then do break-in again?
Call Thomas Distributing and rant?
Use them and not worry about it?

I'd do all of the above, in that order.

And then add:

4. Make mental note not to buy such an unbelievably high capacity battery because it's likely not to be true.

5. Not buy them again because even if it were true, the cell would be so flaky so as to be useless after a bit of use.

 

[Ragiska]

Well, did the break-in cycle on 4 batteries, and at the end of the cycle the charger said 2318, 2301, 2325, and 2336.

Does this seem right for "2900" mAh batteries?

they higher capacity they claim, the crappier the cells actually are.

they probably won't last more than a few cycles either, until they develop high internal resistance and self discharge.

 

[Mr Happy]

Well, did the break-in cycle on 4 batteries, and at the end of the cycle the charger said 2318, 2301, 2325, and 2336.

Does this seem right for "2900" mAh batteries?

Yes, it's about right. You will very rarely find a battery with a true capacity higher than 2500 mAh, no matter what the label says.

 

[shark_za]

Its still 200-300mAh short of the real good quality high capacity cells.

I get over 2550mAh at 500mA from Uniross "Performance" NiMh's listed as 2700mAh.
Thats the best I have.

 

[the_eleven]

Its still 200-300mAh short of the real good quality high capacity cells.

I get over 2550mAh at 500mA from Uniross "Performance" NiMh's listed as 2700mAh.
Thats the best I have.

Fair enough. Guess I was just being overly optimistic......

Is it then reasonable to conclude that all mA ratings as provided by the manufacturers are bunk?

Also, is there a general consensus here, on which are the "real good quality high capacity cells"?

 

[Ragiska]

Fair enough. Guess I was just being overly optimistic......

Is it then reasonable to conclude that all mA ratings as provided by the manufacturers are bunk?

Also, is there a general consensus here, on which are the "real good quality high capacity cells"?

i'll save you a lot of time and heartache. just buy some sanyo eneloops and call it good. your overall performance and happiness will be much better in the long run over any so-called "high capacity" cells

 

[shark_za]

Rather 2000mAh you can rely on now, resting for a few months and after many charge cycles than a 2700mAh that you cant.

 

[Curious_character]

Whoah why do these manufactures label a cell with a certain capacity that is truly not???. I guess certain things in life can't be explained. . ./QUOTE]There's a very simple explanation. They do it because they sell more batteries that way. Like countless others, the OP fell for it. Have you? I hope you don't believe the flashlight lumen output claims. If you do, I've got some real estate I'd like to sell you.

c_c

 

[the_eleven]

With the Delkin "Power 2900 mAh" batteries in question: drain mode + another break in, yields

2399, 2362, 2382, 2376 versus the original 2318, 2301, 2325, 2336.

A meager increase.