How to charge 3.6VDC battery with DC Power Supply

 


I have a few Rayovac Camcorder 3.6V/2500 mAh batteries that I want to
charge.  These were originally charged with a camcorder that I do not
have.  However, I have the next best thing.  I have a DC Power Supply
(BK Precision 1660A) with both voltage control and current control.
Basically I can set this bad boy to output any volt and current
combination.  I have tried charging the batteries at 4.0v and 100mA
and let them charge for about 3 hours.  Batteries never got hot (which
to me would indicate that they were never really charged.)  When I
first unplug them, they register about 3.6v.  However after a day or
so, their voltage drops to 2.6v or so.

So... I am either not charging them up completely or they are no
longer functional.  However, these batteries were never put in
production.  They are old, but they were still in original packaging
as of a few days ago.

Any help greatly appreciated.

jg

 



It would help to know what type of batteries you have.

Tom

 

On Mon, 1 Mar 2010 23:59:19 -0800 (PST), jg


That'll be a Li-Ion battery, judging by the voltage.


Li-Ion batteries don't get very hot during normal use. At such a
gentle charge current, you'd not be able to detect a temperature rise
at all with bare hands. To get the correct charge voltage, you'd have
to check the data sheet, but 4.1V or 4.2V are the normal voltages for
Li-Ion batteries. Be very careful to avoid overcharging them, or
they'll catch fire.


A certain amount of self-discharge is normal. That looks bit too much,
though.


At 4.0V you are probably not charging them completely, and 100mA for 3
hours is only 300mAh, so that is definitely not enough to completely
charge them.


Li-Ion batteries die of old age. High temperatures or incorrect charge
level shortens life. Ideal storage charge is normally specified at
about 50-60%.

If your batteries are more than 3 years old, they're probably pretty
much dead.
--
RoRo

 

Robert Roland wrote:

-- snip --

Could be three Ni-Cd in series, though.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

 

wrote:


It never even struck my mind. Thanks.
--
RoRo