charging a nicd battery

[Brian J. Murrell]

I have a NiCd battery. The charger that came with it seems to have given
up the ghost (died) and I need to charge this battery.

This battery a 14.4v battery pack and I am told by the manufacturer that
it has a 1.5Ah capacity. The charger that comes with the battery
recommends charging for 3-6h so it seems like they are doing a C/3-C/5
charge.

I have a battery charger that has selectable charging voltages and
current, but it only goes up to ~10v. I'm assuming this is no good to me
for this battery pack as I'm assuming I *have* to charge at the full 14.4v
for the required time given the selected current (i.e. the C/n charge rate).

I do have available to me a DC power supply that allows me to select (i.e.
via analog dials) both output voltage and current. Would this be suitable
to charge this battery pack? Should the voltage be set at 14.4v or some
value lower/higher?

Thanx,
b.

 

[Rich Webb]

I have a NiCd battery. The charger that came with it seems to have given
up the ghost (died) and I need to charge this battery.

This battery a 14.4v battery pack and I am told by the manufacturer that
it has a 1.5Ah capacity. The charger that comes with the battery
recommends charging for 3-6h so it seems like they are doing a C/3-C/5
charge.

I have a battery charger that has selectable charging voltages and
current, but it only goes up to ~10v. I'm assuming this is no good to me
for this battery pack as I'm assuming I *have* to charge at the full 14.4v
for the required time given the selected current (i.e. the C/n charge rate).

I do have available to me a DC power supply that allows me to select (i.e.
via analog dials) both output voltage and current. Would this be suitable
to charge this battery pack? Should the voltage be set at 14.4v or some
value lower/higher?

Set the voltage limit to about 1.65 V per cell and the current to your
chosen rate. If you plot voltage and temperature versus time, you'll see
a fairly constant voltage increase from, say, 1.2 V until it approaches
fully charged. At a C/3 or C/5 rate, you may be able to observe the
curve of voltage versus time increase a bit, flatten, and then start to
drop, at about the same time that the temperature vs time curve starts
to rise more quickly. That's just past the full charge point. Stop
there.

Do not leave it unattended. If you don't observe a voltage peak (you
might not if ambient temperature is high to start with) but you do see
the temperature climbing rapidly, terminate the charge. Overcharging
leads to damaged batteries and possible venting of the cells.