Re: How are consumers affected by NiMH and Li-ion cell voltage reversal?



Chris Carlen wrote:
(snip)
My experiences with NiMH cells have convinced me that they take a lot of
care and effort to use effectively.
(snip)

That is my experience too.

Thus I doubt that consumers are ever realizing the full
potential of these cells ...
(snip)

I believe that is certain.

(snip)
... without the proper care which I suspect most folks never give these
cells, they are likely to seem like junk, with very poor lifetimes and
performance in gadgets.

Probably true.

But .... all that can be said of NiCD as well, yet people kept right on buying
them, buying NiCD replacements for reversed NiCDs, buying tools and appliances
and toys with built-in NiCDs. Today people allow devices to pull down NiMH; ten
years ago they abused NiCDs similarly. The only things that have changed in the
mean time are battery chemistry, battery capacity, and the box that loads the
cells.

P.S. I have also recently tried rechargable Li-ion CR123 shaped cells.
Just a pair of them in an LED flashlight. Sure enough one cell
collapses before the other and now that cell has slightly higher
self-discharge rate than the other.

A 1-cell, LED flashlight (w/ voltage-boost, of course) wouldn't have that
problem. (But ya still gotta be careful not to let the load suck the guts out
of the rechargable.)

It seems cells need to have a diode built in to limit reverse voltage to
a non-damaging or at least a very minimally damaging level (maybe a
Shottky).

What? And drop the screwy 1.2v to an even lower value?
.

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