Two RS cells wont charge in fast charger

Hello,

Already i have two Radio Shack 1800mAh NiMH cells (out of 4 from the pack)
that wont charge in the Energizer 15 minute charger. They have been
charged about 10 times or so and already they are not accepted by
the charger. The other two still work ok in it.
It's strange that they went so fast.

I am also finding that the 2500mAh Energizer NiMH cells self discharge
pretty quick. I charged them about two weeks ago, used my light for
about 5 minutes, then didnt use it for two weeks, now they read
0.95 volts (all four). I stuck them in the slow charger to see if they
do any better after a slower charge.

Hello Al,

Try holding the cells in your hand for a couple of minutes to heat them up. The 15 minute chargers reject cells when their internal resistance goes up.

The Energizer 2500 mAh cells are known to have problems. It seems there is a bad batch of cells out there. Sanyo and Powerex 2500 mAh cells have also had some of the same problems.

Contact Energizer, I think they will replace your cells.

Tom

Al, have you tried removing power to the charger, inserting the cells and then plugging it in? I have had some success with that method with my Duracell 15min charger on fussy cells.

Paul

Hello again,

Tom, thanks for the suggestion. Do you know how people contact Energizer
to get new cells? Email? Other? Thanks.

Paul, i havent tried that but i will next time. I did try cleaning the batteries
contacts (that helped once) but it didnt help this time.

Hello Al,

I believe people have called the Energizer help line and gone from there...

Tom

Mr Al, I've had three out of four HR 2500mAh cells fail on me.

Are the 1800mAh cells charging in other chargers? Are they up to the rated capacity? Have you tried putting them in another charger for a few seconds (30-60) before putting them in the 15 min charger?

Hello again,

Ok thanks Tom, i'll probably end up doing that.
One thing i forgot about though, is that they were always installed inside
a headlamp of mine, and although it was off, there could be leakage causing
this, so i am doing a test now as i have just finished charging the four cells
and i will let them sit untouched at room temperature for a week, then measure
the terminal voltages, then two weeks, and i suspect after that they will be
dead again, but i'll wait to see. If so, i'll call Energizer.

ee:
Yes the cells seem to charge in the slow charge ok. I dont think they were
ever up to capacity though, perhaps i should test them again.
You know i was going to try that and i forgot to do it. I'll try that next time too.
Thanks for the suggestion.

Hello Al,

If you can manage it, I would be interested in what the internal resistance of your Radio Shack cells are.

Tom

Hi again,

Tom, i had four Digital brand cells with rather high internal resistance and
they would never charge in the Energizer 15 minute charger. I didnt sweat
it though, cause i had several other cells that did charge ok including
four Duracell 2050 cells.

I know the internal R test is pretty picky, because i tried using jumpers to
connect the AA cells to the AAA connectors on the charger and all i got
was a blinking red LED I used short jumpers too. Perhaps i'll improve on
this test once the warranty runs out...i'll solder a new AA cell holder right
to the darn circuit board with nice heavy leads to see if i can charge AA cells
using the AAA algorithm which is half current. I would think the AAA cells
are allowed to have slightly higher internal R so it might work, although it
will take 30 minutes to charge AA's instead of 15 minutes, but only those
that have higher internal R would have to be done this way.