> NIMH cells vary widely in their acceptance of long term overcharge (trick=
le).
> Some specify that you shall never charge them this way. Others will
> accept a C/10 overcharge without damage. =A0The difference is in the
> exact construction of the cell, determining how well it handles the
> resulting free oxygen and hydrogen.
>
> Because of this wide variability, one should not generalize.

You were right up to that point ;-).
But,

> Olin is correct,

No. Olin was wrong the first 2 (maybe 3 without checking) times he answered=
..
If anyone else had answered a question the way he did he would have
been typically rude and scathing about it.

Your technical answer is good (as I'd expect :-) ) and is the sort of
thing that VG needed to know.
That answer was obvious enough to you and to me and to Olin.
It was, evidently, not obvious to VG, even though by now we all would
sort of hope it would be.

But, Olin misinterpreted the question in order to take an opportunity
to be rude, then he did it again.
VG then pointed out the explicit difference between what Olin was
answering and the actual question.

Olin did hen address the actual question, and his answer was correct enough
eg summarises as: '"if you exceed what the data sheet allows you can
expect significant damage", and he is not obliged to give any answer
or good answers, or very good answers, but the 1st few attempts giving
wrong answers and being constructively obstructive seems to fall below
the acceptable hurdle.

Olin is right - if you exceed data sheet specs then significant damage
may occur.
Dave is right that Olin is right if you ignore Olin's first 2 answers.
Dave is much more right - viz: look at the data sheet for the device
concerned. Results vary widely and some batteries ARE liable to be
somewhat damaged by the potential level of overcharge involved.

Good additional answers:

Throw the charger away OR keep it for use where you can control how it
is used or where you don't care what it does or where you know it
doesn't matter.

You can buy super cheap chargers that cost less than the eneloops do,
that will treat them better. Consider doing so.

If you can educate your friend to behave more intelligently than you
suggest they may do then consider doing so. If you can't manage this
for whatever reason, consider not lending then the equipment if you
care about the worst case outcomes more than you care about how they
would feel about your action, or consider not caring about the
outcomes if you care more about their need and how they feel about
what you do.

MOST reputable manufacturers of high capacity NimH cells would advise
that 150 mA overcharging for more than a 'short while" WOULD cause
some damage. Damage is probably measured in loss of cycle life and
probably also some diminution of capacity.

For magnitude of 'some' see any of Olin's answers ;-)


        Russell







go to the web site, find the data sheet, and read it.
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