Hello Everyone, I am coming here after a long time. I remember those days when I used to stick to the screen and watch all the posts here and gather as much information as I could. Then I got a job and everything changed . No more time for new circuits any more.
Anyways, I was looking for a simple circuit which can be build using the parts which are easily available.
As you can see, I am from India and getting a universal charger from overseas is pretty costly!
I need a charger which can charge a battery pack consisting of 6 AA 2100Mah Cells which theoretically 7.2V.
It would be great if I can power that charger from regulated 12V DC off a spare computer SMPS.
I do not need a PCB diagram as I will construct it on a normal board which has a lot of holes for solder(Don't know what its called).
I assume your cells are Nicads or Ni-Mh. You should always charge these from a constant current source. If you assume the charging voltage to be about 1.35V per cell you can feed them in series from your 12V supply via a resistor that will drop about 4V.
The recommended charging rate for 2100mA cells would be 210mA. An 18ohm 2W would give a charging current of 217mA so should be OK. Charging from the fully discharged state would take 14hrs
Energizer and two Japanese Ni-MH cells manufacurers advise NOT to trickle-charge them at more than only 1/40th their capacity. Each cell might reach 1.5V when fully charged. A charger IC should be used that regulates the charging current to 1/10th the capacity then it disconnects when it senses a full charge.
NiMH charger
Posted - Jan 16 2013 : 09:49:58 AM
. No more time for new circuits any more.
