In article .com,
Andy wrote:
I was just looking through the Mar/Apr issue of Wood magazine, where
they did an article on myths of rechargable batteries. One thing they
said really confused me - they said that rechargable batteries should
NOT be discharged completely, and that you should recharge them as soon
as you feel your tool slowing down, because if a cell is totally
discharged it can switch polarity and ruin the whole battery (or
something like that). I'd always heard that with NiCad batteries, you
DO want to discharge them completely, so they don't develop a 'memory'
and accept less of a charge each cycle. Does anyone have a good
explanation for why one or the other is true, or firsthand experience
trying it both ways?
Also, they said that NiMH batteries are really not superior, because
even though they can have larger amp-hour ratings, they don't last for
as many charge/discharge cycles. I'd also read elsewhere that NiMH
batteries don't develop a memory, which seems to me like it would make
them last longer. Has anyone used both types side-by-side through the
whole life of a battery?

NiMH batteries are good for *fewer* charge/discharge cycles than NiCad.
you get more watt-hours in less space, but pay for it with reduced cycles.
I'm don't know just where it works out in terms of 'lifetime" watt-hours.
I suspect that NiMH are a tad more expensive per lifetime watt-hour.

*early* NiCad batteries did have a 'memory effect'. If you're dealing
with batteries manufactured in the last 15 years (at least), it is a
_non-issue_, due to changes in battery design.


Running NiCads MULTI-CELL BATTERIES _all_the_way_dead_ is a bad idea, for
the reasons mentioned in your posting. When dealing with SINGLE CELLS
(1.2V units) running them all the way down is not harmful, and can extend
lifetime _somewhat_.

NiCads have a fairly sharp 'knee' in the output curve -- when output starts
to fall off, they are "quite close" to being totally run-down.