# Charging a NiCd battery pack

S

#### shred00

Jan 1, 1970
0
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.

H

#### Homer J Simpson

Jan 1, 1970
0
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?

Do what I do. Stick an analog meter in series and charge at a reasonable
rate while watching the current.

S

#### shred00

Jan 1, 1970
0
Homer said:
Do what I do. Stick an analog meter in series and charge at a reasonable
rate while watching the current.

Does it have to be analog? Can I use digital? I only have digital
meters.

Will putting a digital meter on the + and - output of the power supply
and setting the meter for the correct DC range read the current being
supplied from the power supply? Or do I have to have a load on as
well? I would think the latter since the current has be being drawn by
you can see)

b.

H

#### Homer J Simpson

Jan 1, 1970
0
Does it have to be analog? Can I use digital? I only have digital
meters.

Sure, but some DMMs turn off after a period.
Will putting a digital meter on the + and - output of the power supply
and setting the meter for the correct DC range read the current being
supplied from the power supply?

No. You need to put the meter in series to read current. And you'll need a
little more voltage with a DMM because they usually drop more volts than an
analog meter.
Or do I have to have a load on as
well? I would think the latter since the current has be being drawn by
you can see)

http://hobby-electronics.info/course/ from another poster here.

J

#### jasen

Jan 1, 1970
0
Does it have to be analog? Can I use digital? I only have digital
meters.

analog meters typically cost less to run.
Will putting a digital meter on the + and - output of the power supply
and setting the meter for the correct DC range read the current being
supplied from the power supply? Or do I have to have a load on as
well?

stick it in series with the batteries. use the 10A range.
I would think the latter since the current has be being drawn by
you can see)

without the load the meter onb the amps scale behaves like a short circuit
and something will possibly be damaged.

S

#### shred00

Jan 1, 1970
0
Homer said:
No. You need to put the meter in series to read current. And you'll need a
little more voltage with a DMM because they usually drop more volts than an
analog meter.

I tried this. I put the meter between the + output of the power supply
and the battery and the DMM read nothing. I also tried connecting the
device to the power supply with the DMM between the + of the power
supply and the + of the device and turned on the device. The device
didn't work and the DMM read nothing. The device works on the power
supply without the DMM in series.

I also tried putting the DMM between a charged battery and the device
so that the DMM was between the + terminal of the battery and the
device and again the device didn't work an the DMM read 0 while the
device was on.

I feel like I am missing something fundamental.

b.

H

#### Homer J Simpson

Jan 1, 1970
0
shred00 said:
I tried this. I put the meter between the + output of the power supply
and the battery and the DMM read nothing. I also tried connecting the
device to the power supply with the DMM between the + of the power
supply and the + of the device and turned on the device. The device
didn't work and the DMM read nothing. The device works on the power
supply without the DMM in series.

I also tried putting the DMM between a charged battery and the device
so that the DMM was between the + terminal of the battery and the
device and again the device didn't work an the DMM read 0 while the
device was on.

I feel like I am missing something fundamental.

Did you switch the DMM to a current range AND plug the probe into the
current socket on the DMM?

S

#### shred00

Jan 1, 1970
0
Homer said:
Did you switch the DMM to a current range AND plug the probe into the
current socket on the DMM?

Sure did.

Set the DMM to read DC current (in the range labeled with an "A" with a
solid and dashed line above it) on the "200m" setting (200 milli-apms
IIUC).

Now wait. I just tried the red lead in the 10A plug and setting the
10A selector on the DMM and when I set the bench supply to .15 (amps) I
in the (up to 200mA) socket and the 200m selected on the DMM but fine
in the 10A plug. Strange.

Looks like I am charging now. I'm assuming the DMM continues to
conduct the current when it's switched off.

H

#### Homer J Simpson

Jan 1, 1970
0
Looks like I am charging now. I'm assuming the DMM continues to
conduct the current when it's switched off.

Not an assumption I would make although it may be true. That's why I prefer
an analog meter for this.

P

#### Peter Bennett

Jan 1, 1970
0
Now wait. I just tried the red lead in the 10A plug and setting the
10A selector on the DMM and when I set the bench supply to .15 (amps) I
in the (up to 200mA) socket and the 200m selected on the DMM but fine
in the 10A plug. Strange.

Looks like I am charging now. I'm assuming the DMM continues to
conduct the current when it's switched off.

Sounds like you blew the fuse in the meter's 200mA input circuit.

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