con't

I found a bunch of Maha 2300mAh AA's that are probably a couple years
old, unopened packages.

Only 6 of 8 would take any charge at all. Two were flat dead and
would not accept any charge, even from an old and determined
Crane quick-charger, that has a reputation of being willing to charge
anything (modern chargers refuse to charge batteries that are too
discharged, meaning that you ought to keep one old charger around
at least, to get the charging started on very empty batteries).

The 6 remaining are rejuvenating in a LaCrosse charger, at the moment only
up to 800mAh in capacity after several cycles.

On the other hand, the NiCd batteries in my power drill are good after
years.

Maybe that's an important difference in the chemistries.

Not only self-discharge rate, but death from neglect.
--


On the internet, nobody knows you're a jerk.

On Oct 5, 5:06 am, Ron Hardin wrote:
con't

I found a bunch of Maha 2300mAh AA's that are probably a couple years
old, unopened packages.

Only 6 of 8 would take any charge at all. Two were flat dead and
would not accept any charge, even from an old and determined
Crane quick-charger, that has a reputation of being willing to charge
anything (modern chargers refuse to charge batteries that are too
discharged, meaning that you ought to keep one old charger around
at least, to get the charging started on very empty batteries).

The 6 remaining are rejuvenating in a LaCrosse charger, at the moment only
up to 800mAh in capacity after several cycles.

On the other hand, the NiCd batteries in my power drill are good after
years.

Maybe that's an important difference in the chemistries.

Not only self-discharge rate, but death from neglect.
--


On the internet, nobody knows you're a jerk.

I had a similiar problem with my Maha 2300mA batteries too. After
about 3 year their (4 of them) capacity went down to about 800mA or
so . Even a smart charger would not rejuvinate them. I cured this by
luck. I completety discharged them (in a flashlight) and rercharged
them twice. Crude conditioning you might say. It has worked so far as
they are now back to +2000mA capacity. Whew! These batts cost me $20
back then. I live on a tiny South Pacific Island where just about
ANYTHING is unobtainable so replacements would have to be mailed in
which takes about a month.
I'm guessing that they had some sort of memory effect as the radio
(7600GR) obviously cannot fully dischage them or they are just crappy
batteries. Your comment?
Cheers, Chris

wrote:

On Oct 5, 5:06 am, Ron Hardin wrote:
con't

I found a bunch of Maha 2300mAh AA's that are probably a couple years
old, unopened packages.

Only 6 of 8 would take any charge at all. Two were flat dead and
would not accept any charge, even from an old and determined
Crane quick-charger, that has a reputation of being willing to charge
anything (modern chargers refuse to charge batteries that are too
discharged, meaning that you ought to keep one old charger around
at least, to get the charging started on very empty batteries).

The 6 remaining are rejuvenating in a LaCrosse charger, at the moment only
up to 800mAh in capacity after several cycles.

On the other hand, the NiCd batteries in my power drill are good after
years.

Maybe that's an important difference in the chemistries.

Not only self-discharge rate, but death from neglect.
--


On the internet, nobody knows you're a jerk.

I had a similiar problem with my Maha 2300mA batteries too. After
about 3 year their (4 of them) capacity went down to about 800mA or
so . Even a smart charger would not rejuvinate them. I cured this by
luck. I completety discharged them (in a flashlight) and rercharged
them twice. Crude conditioning you might say. It has worked so far as
they are now back to +2000mA capacity. Whew! These batts cost me $20
back then. I live on a tiny South Pacific Island where just about
ANYTHING is unobtainable so replacements would have to be mailed in
which takes about a month.
I'm guessing that they had some sort of memory effect as the radio
(7600GR) obviously cannot fully dischage them or they are just crappy
batteries. Your comment?
Cheers, Chris

The 7600GR is hell on rechargeable batteries if left in, since the current
draw when off is considerable. That means that the weakest battery goes
empty and then gets reverse charged, pretty quickly (about a month of
inactivity is enough to do it). Take them out and put recharged ones in
pretty often, so that the weakest battery stays charged.

What brings NiMH that have self-discharged back to life isn't clear to me.
I've had a few come back after many charge and discharge cycles in the
La Crosse rejuvenator mode. I don't think it's a memory effect, since
they're fully discharged. In fact that seems to be what provokes the problem.
--


On the internet, nobody knows you're a jerk.

"Ron Hardin" wrote in message
...
con't

I found a bunch of Maha 2300mAh AA's that are probably a couple years
old, unopened packages.

Only 6 of 8 would take any charge at all. Two were flat dead and
would not accept any charge, even from an old and determined
Crane quick-charger, that has a reputation of being willing to charge
anything (modern chargers refuse to charge batteries that are too
discharged, meaning that you ought to keep one old charger around
at least, to get the charging started on very empty batteries).

[snip]

Sounds like a good question for sci.chem.electrochem.battery.

Frank Dresser