Hi,
I have built the charger circuit based on the MAX712/MAX713 from this site:
Fast, smart and universal NiCd/NiMh battery charger
I've tried with both used and brand new NiMh batteries of 1100 and 1300mAh capacity.
The circuit seems to work fine, except that it SWITCHES OFF after about 15-20 minutes of charging!
(After no more than 5 pictuers, my camera turns off saying that batteries are depleted)
Set to 4 hours max charge time according to datasheet of MAX712. (PGM2, PGM3 = BATT-)
I also tried from 1 cell to 4 cells, (+ dip switches changed) Rsense 0.6 and 1 Ohm, Rshunt 0,6K and 1,4K Ohms with same results.
Charging currents are fine. (250mA / 1 Ohm, 415mA / 0,6 Ohm)
What could be wrong? What should I check?
Could be that I am using a BD 434 on a decent heat sink? By touch it's slightly warm, I'd say around 45-50 deg C, so it handles that current easily.
Thanks and Happy New Year!