On Sun, 14 Aug 2011 08:34:04 -0700, "William Sommerwerck"
wrote:

If that's true (and I assume it is), it's the first really significant
difference between nicads and NiMHs I've heard of.

I must admit that I didn't know that either. I had always assumed the
NiCd and NiMH cells were interchangeable in chargers. I guess not.

It also explains why my C9000 charger doesn't shut off when I charge at
"only" 0.3. Guess I'll have to change the way I charge."

I've been playing with charging individual cells at 5C or higher.
Works fine as long as you know exactly how long to charge, condition
of the cell, and ambient temp. From experience, the battery does NOT
get hot until it's overcharged.

I stand corrected. HOWEVER... No one would consider 0.1C a trickle charge,
as it has traditionally been the "standard" charge for regular nicad cells.

I didn't say trickle charge. According to Motorola, it's a
"maintaining" charge, whatever that means. I agree that a trickle
charge would be much less. However, my experience is that you cannot
charge a NiCd battery with anything less than about 0.05C. It just
never comes to full charge. I don't know what causes this effect and
don't want to go Googling for references right now.

It's also possible this might have been a memory effect.

There's no such thing as NiCd memory effect unless you're talking
about space qualified batteries.
http://en.wikipedia.org/wiki/Memory_effect
I have yet to see data, numbers, and reproduceable tests that
demonstrate memory effect. What I have seen are problems with
electrolyte loss, caused by overcharging and subsequent venting, that
mimick the problem. Incidentally, I found this by carefully weighing
the better before and after overcharging. It's not much loss, but
it's always present.


--
Jeff Liebermann
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Santa Cruz CA 95060 http://802.11junk.com
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