maybe slightly offtopic, but I hope someone can give me an advice.
My device is a cash register that works 9-20, then turned off overnight. While powered off, CPU (mega128) is fed from small 40 maH NiMH battery; CPU sleeps in powersave mode and wakes up every second from Timer0 interrupt to keep real time/date. While powered on, backup battery gots 1ma trickle charge.
The question is: Does anybody have practical experience in using NiMH battery for such purposes? What charging algorithm is the best (maybe not the best, but just suitable)?
Different sources found with google give different recomendations...