Appraising small rechargeable batteries

[JD]

Hi Experts,

I have many small rechargeable AA and AAA
batteries and find it hard to appraise them.

1 How to determine if they have some life left? I
know I can charge them for 24 hours and then see
how long they last in operation, but that could
take a lot more than 24 hours to tell if they are
good.
2 Should they be stored when they have been fully
charged or should they be left in a
rundown state until they are needed and then charged?
3 I have seen a comment recently that small
batteries should not be stored near one another.
If true, how far apart should they be?

Any other relevant comments would be appreciated.

TIA

 

[Jasen Betts]

Hi Experts,

I have many small rechargeable AA and AAA
batteries and find it hard to appraise them.

1 How to determine if they have some life left? I
know I can charge them for 24 hours and then see
how long they last in operation, but that could
take a lot more than 24 hours to tell if they are
good.

that's the only way i know of.

Get a cheap quartz clock and wire a 1.2v flashlight bulb (or a 4.7 ohm
resistor) in parallel witn the battery holder, put each cell in and
see how long the clock runs for. (should be less than 12 hours, the
clock will tell you how long it ran for)

2 Should they be stored when they have been fully
charged or should they be left in a
rundown state until they are needed and then charged?

doesn't make much difference.

3 I have seen a comment recently that small
batteries should not be stored near one another.
If true, how far apart should they be?

Just be sure they don't short out, this requires more care with "9V"
and "lantern" batteries. than with AA and AAA

 

[Grant]

This appeared on the groups awhile back and works pretty well:

You buy a cheap analog quartz clock, wire a dummy load resistor across
the battery contacts, put a freshly charged battery into the holder
and see where the clock stops - then calculate the capacity in amp
hours.

A few refinements like a switch and outboard battery holders will work
wonders. I test mine then use a "P-touch" label maker to put the
actual capacity on the side of the battery.


Good question. If they are fully charged they just run down anyway if
they aren't used. To get the most out of the batteries use them right
after charging.

The newer slow self discharge ones are great - so great I threw out my
standard NiMH types and bought all "pre charged" batteries - they hold
a charge for many months, not just a week or two.

No reason not to store them together. That sounds like a myth.

You can refrigerate them to make the charge last longer though -
providing there isn't a lot of water condensing on them.

Seriously: Switch to low self-discharge batteries! It saves a lot of
aggravation.

Yes, but not chuck out the older style NiMH, kids love them for toys

I've got some of the new style charge holding batteries as they suit
my usage patterns much better.

Another thing is use a decent charge that charges each cell individually,
and do try to charge at the recommended C/10 rate (it's quoted on the
battery), unless you're really in a hurry. Fast charging stresses the
battery more. So I set my charger to charge 2100mAH AA cells at 200mA,
rather then the default 1000mA which is the fast charge for those 2700mAH
high self-discharge style AAs.

An overnight charge is usually okay. Found four of these I forgot I had,
all measured over 1.2V no load after more than six months in storage.

Grant.

 

[JD]

I use NiMH cells in my Canon camera. I don't think I've charged them
10 times in the last year, while shooting 1600 pics and maybe an hour
of video. I haven't noticed any self discharge issues and I didn't buy
any special cells for it.

G²

My apologies for my belated reply. This was very
helpful and enlightening.
Have a great weekend