Thanks for the reply, guver. Yes, I expect it's normal for this simple, inexpensive charger. The computer graph and the charger display both indicate the current goes to zero but doesn't reverse. I just wonder what the designers achieve with this action. Perhaps it is as you suggest, an open circuit voltage test for something??

Incidentally, looks like my battery is not too good. It hasn't been cycled much (haven't flown the plane yet) and the charger is only moving about 500 mAh into and out of the battery. Guess I'll cycle it a few more times and see if the capacity improves!

Frank