16 Cell NimH charging Circuit?

[IanB]

Actually, it is not a good idea to leave NiMH cells on permanent trickle charge. It puts wear on the cells and will hasten their end of life. For most kinds of NiMH cell it is best to store them in a state of moderate discharge and give them a full charge just before use. However, the modern design of low self-discharge cell like the Eneloop seems to behave differently and storing them fully charged seems to be OK.

The commercial chargers do look for the voltage slope, but the better ones use a temperature probe and look at the temperature as well. Also it is recommended to charge at the 1-2 hour rate to maximize the end of charge signal. Lastly, the commercial chargers are fairly clever about exactly how they detect the end of charge condition. They don't just look at one thing in isolation.