No, the research was done using single cells, not multi-cell packs. And they
didn't discharge them to "flat", but rather stopped at something like 5%
capacity. They wanted a "deep" cycle, but not a deadly cycle.

Ed
wb6wsn



"Chuck Tribolet" wrote in message
...
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