Battery charging - the other way

ro · Post by ro » Thu Mar 11, 2004 4:40 am

Since I don't have a charger at hand, I need to charge the battery of a GP 1200 manually (by taping the wires of the power supply to the corresponding contacts on the battery).
What voltage and current would you recommend?

And... which contacts on the battery do I have to connect to the power supply?

Thanks,
Ro

Andreas · Post by **Andreas** » Thu Mar 11, 2004 5:42 am

12V 120mA for 12 hours.

Andreas

Will · Post by **Will** » Fri Mar 12, 2004 2:33 am

What is the battery voltage on a GP1200?

I would NOT use 12 volts on any battery, the battery WILL explode and all those little pecies of metal become shrapnel. DO NOT take any chances.

Battery chargers use a constant current, not voltage to charge NiCad, and NiMh batteries.

120 ma constant current for 14 to 16 hours is correct. Older chargers used a lamp in series with the voltage going to the battery, the lamp acts as a constant current device.

ro · Post by ro » Fri Mar 12, 2004 2:46 am

It's a 7,5 Volts 2000mAh NiMH battery.
What voltage would you recommend for charging?

I have to add that this is just a temporary solution until I get the real charger from eBay.

Will · Post by **Will** » Fri Mar 12, 2004 11:34 pm

With a current limited power source. Limited to 200ma. Use a resistor if needed, 27 ohms is close if using a 13 volt source.

elkbow · Post by **elkbow** » Tue Mar 16, 2004 7:41 pm

I agree with Will, the charging factor is current driven, not voltage driven.....the technique Will noted will work fine.....

ro · Post by ro » Thu Mar 18, 2004 1:30 pm

The Battery has four contacts on the back. On which contacts do I have to put the positive (+) and negative (-) current from the power supply?

Ed · Post by Ed » Thu Mar 18, 2004 1:51 pm

Looking at the back of the battery:

The most left is your (-), the most right one is the (+).

Always check for polarity!

Ed