They may have done the other BAD thing --- over-discharging.
When you run an NiCD pack DEAD flat, the weakest cell gets
reverse polarized, and that's death to that cell. One dead
cell means the pack is kaput.

--
Chuck Tribolet

http://www.almaden.ibm.com/cs/people/triblet

Silicon Valley: STILL the best day job in the world.


"Ed Price" wrote in message news:0CxAc.24993$0z6.18587@fed1read07...

"Chuck Tribolet" wrote in message
...
Because you leave them on simple trickle chargers long term, which causes
little
whisker crystals called dendrites to form inside the battery and short it
out internally. I get a heck of a lot of recharge cycles out my
rechargeables.
I use smart chargers that just about shutdown (go way below "trickle")
when
the battery is charged.

--
Chuck Tribolet


I believe that, as the crystalline area grows, it obscures the usable plate
area, which is what causes the "memory" effect. I read some recent research
(which I now can't find) where new cells were put through a careful charge
and then a deep discharge cycle. Then, the cells were deliberately
overcharged. Instant loss of capacity; the "memory" effect instantly
duplicated. OTOH, another group of new cells were put through many shallow
discharge cycles, with careful recharging. Result, no memory effect. Then,
with one overcharge cycle, the memory effect was now there.

Seems to confirm the concept of "memory", it's just that the culprit is the
charge profile, not the discharge portion. And that means that dumb
"trickle" chargers are really cell killers; we need to use smart chargers
exclusively.

I wonder if NiMH chemistry shows the same effect?

Ed
wb6wsn