"I checked it, and yes my pack shows then a tension of around 15V. To
avoid an deep discharge in one of the cells, I start to recharge the
pack when the LED stops to light. I´m limiting the charging time to 4
hours to avoid overcharge in the cells."
You may still be over-discharging one of the cells, particularly as the
battery pack ages.
The problem is that when you have 12 cells, one of them can go to zero
and there's still enough voltage to drive the motor correctly. This is
very likely to happen with NiCds, because they have a very abrupt "knee"
in their discharge curves -- the voltage is almost constant for a long
time, then, over a period of a few minutes, it drops precipitously.
Discharging a cell to zero volts doesn't do any good. The cell is then
reverse-charged by the other cells, further damaging it.
I recommend giving your M.15V a _brief_ recharge (10 or 15 minutes, say)
after every two or three rolls of film. Don't wait until the light
blinks or goes out. How this will affect "memory," I don't know.
Considering that the M.15V charger pumps far more current into regular
NiCds than they were designed for, even a 4-hour charge strikes me as
too much.
"NiMH are supposed to be WORSE than Nicads with regard to
self-discharging. I've seen web pages that describe it as being as high
as 15% PER DAY -- but I believe that to be an extreme figure."
My M.15V with new NiMH cells installed by JH came back about 3 weeks
ago, and I charged it for two hours. The charge has "held." The current
voltage is 16.8 volts.
"You can "top-off" NiMH any time you want and I don't THINK you can do
that with NiCds without FIRST draining them -- I think even "smart" NiCd
chargers do that (I could be wrong on this point, however)."
Many chargers for camcorder batteries have a quick-discharge feature
that drains the pack before recharging.
"Has anyone made a charger for the Control Pack to be charged off a car
cigarette lighter plug, like we have with our cellular phones?"
The problem is that the battery is, at best, 13 volts, while the pack is
15 volts. (I just checked mine, and it's over 16!) You'd need an even
higher voltage to get a constant-current charge. You would therefore
need a circuit that steps up the voltage.
A simpler solution is to buy an inverter that converts 12V DC to 120V
AC. You can then run the standard charger from that. They cost about
$50.
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