"Dan K" wrote in
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wrote in message
oups.com...
How to recharge new NiCad battery
I bought a new 18 volt cordless drill-driver
that has 1200 mAh recharceable NiCad battery.
What is the best way to get longest battery
life out of it?
Alzerimers setting in? Can't remember if you
completely discharge first or fully charge to
get longest life.


Your getting a bunch of different answers, so here's mine: Its been
my experience that store bought chargers have one object in mind, to
charge the battery fast.

Which is best for them.
Those slow chargers don't measure battery temp or any parameter;they are
just current sources,and can overcharge or undercharge your battery
pack.Uusally overcharging them,shortening their life.

They really don't care if your battery dies
a year from now. I've had store bought chargers that actually get a
battery hot when its charging.

Which is normal,if not overdone.

I've thrown out my store bought
chargers or modified them to charge at a reduced rate. Always start
with a discharged battery (don't charge a battery that doesn't need
charging) and put it on a timer so you know how long its been charged.

How do you know how long to charge it?
How do you determine the pack's amount of depletion?
Modern smart chargers(all fast chargers) measure deltaV/deltaT,and know
when to shut off the charge.


I too have just gotten a couple new 18v drills with 1200 mah
battery's. These are the first cordless drills I've owned. The
charger said to charge for 5 hours and I measured a charge rate around
350 ma. Do the math: 5 hrs at 350 ma = 1750 mah into a 1200 mah
battery. Not too bad, but I modified mine with a 13 ohm resistor to
get the charge rate down to around 200 ma and will charge them for 8
hours (beacuse I just happen to have a nice 8 hour timer). I'll keep
one of the chargers un-modified and use it to quick charge if
necessary for an hour or two, but the 8 hour one will be what I use
most of the time.



When you buy the new Lithium-ion packs,they will have their smarts built
right into the pack,to insure the proper charging.

BTW,the cheapo drill/drivers are the ones that come with 3-5hr
chargers,that shorten battery life,and good battery packs have mAH ratings
of far more than 1200mAH. That's puny for a sub-C cell.


--
Jim Yanik
jyanik
at
kua.net