After I wrote that, which is obviously the wrong sequence, I did a quick
search and found that a constant current plus voltage/temperature sensing
was preferred. My recollection of the fully charged voltage was also much
too high!

Peter


"Scott" wrote in message
.. .
Um...last time I checked, Nicad batteries were charged with a constant
current source, not a constant voltage soure. You can use a regulator IC
with a properly connected resistor to make a constant current source.

Scott


Peter Dohm wrote:
"Morgans" wrote in message
...

"Ernest Christley" wrote


Dang-it! I bet you're right.

I noticed the batteries coming out of the new charger a lot warmer than
the came out of the old one. I bet I would still have decent batteries
if I had kept the old charger.

Perhaps you could stick a voltage regulator chip into the charger, or
experiment to find a resistor that would drop the voltage to a reasonable
level.
--
Jim in NC


The voltage regulator is the only correct solution, although I don't
recall the proper shut-off voltage. Ideally, the charger should provide
a fairly quick charging current and then shut off, or else drop to a
couple of milliamps when the fully charged voltage is reached.

IIRC, if the batteries are to last, the correct voltage varies with
temperature and should be controlled within about 0.1 volt. I don't
recall the correct voltage for a full charge, but 9.6 volts sounds like a
stack of 8 nicad cells; so the figure of 11.6 volts sounds possible for
some fairly normal temperatures. However, that is a distant and somewhat
foggy memory--so it is only usefull as a starting point to search for the
correct numbers.

I hope this helps.

Peter




--
Scott
http://corbenflyer.tripod.com/
Gotta Fly or Gonna Die
Building RV-4 (Super Slow Build Version)