Automatic digest processor wrote:
<snip>
> Well, here is why I ask.  I charged this pack up over 15 hours, and then
> connected my pic.  The pic ran for about 5 minutes and then stopped.
> Voltage on the batteries was 4.1V and falling.   I measured the current
> drawn by the pic circuit.  It was only pulling about 60mA.  Why didn't the
> batteries last MUCH longer?!?
>
> I am either not charging the pack correctly or I have a bad cell.  If I
> have a bad cell, is there any easy way to test this? They were supposed to
> be new batteries, they were expensive ($7 bucks each) .

Did you measure the current and voltage while you were charging the
cells? The applied charge voltage needs to be higher than the 4.8 volt
nominal battery pack voltage in order to successfully charge it. How
much higher depends on the internal resistance of the individual cells,
the wiring, etc. and the current limiting resistor you use to obtain
your desired 60mA current. If you increase the charge voltage until you
measure the desired 60mA rate with the resistor you've chosen I think
your results will be much better.

--

Tim McDonough
Springfield, Illinois USA