The lithium packs that I'm familiar with (laptop, misc) are complicated..
and some types are potentially hazardous as far as overheating, but then
almost any energy storage device is hazardous when mishandled.
Some good brands of NIMH cells with tabs are, IMO, good replacements for
building battery packs for portable equipment, and although the technical
aspects of charging differ between NICD and NIMH, the NICD chargers could
also charge NIMH packs well.. if the charger a moderate-charging-rate delta
peak sensing type (not a fast/high-rate/timer type charger).
When comparing cheap grades of different cell technologies, all bets are
off, there's no point.
Better grades of cells are in a separate class. The best quality/grades of
cells have typically been from Japan.
There are a lot of different specific cell characteristics for different
grades of cells.. info from Sanyo or Panasonic give very good descriptions
of their different grades.
Some sources state that NICD are better for cordless tool requirements of
intermittent, moderately high drain, power.
The equivalent cell size of a NIMH will provide considerably more Ah
capacity, which can be a significant benefit for many applications (not
primarily cordless tools).
When considering replacement of cells in older packs, one should also be
considering upgrading to newer charging units. The old charger is likely to
be out-of-spec and/or possibly near failure.
I don't test/check out new chargers or cells unattended.. just the same
habit as when charging LA lead-acid batteries.
For many of the HSMs here, replacing/bypassing the board of an existing
charger probably isn't too complex, for reusing the old charger case
receptacle for the existing OEM battery packs.
Some cordless power tool packs contain internal temperature protection
circuits or other safety devices which shouldn't be ignored.
I've been using some universal Powerizer NIMH-NICD chargers for over a year
with very good results. These are 2-wire chargers, although one or more
models come with a temperature sensing lead to prevent battery pack
There are some models that are AC line voltage input only, or DC input
(auto/truck lighter socket cord, or AC adapter input).
Some of the MRC brand chargers have a wide variety of selectable features
for different cell types and capacities.. generally limited to up to 12V
maximum pack voltage, as they come supplied with 12V inputs for
portable/mobile use (can also be used with 12VDC AC adapters).
"Winston" < snipped-for-privacy@BigBrother.net> wrote in message
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