I like the higher capacity NiMH cells. But these high capacity cells need so much more charge that a fast charger (or much more charge time) is needed.
Many fast chargers nowadays decide that full charge is approaching by sensing the moment when there is a slight drop in cell voltage. (Negative delta V.)
However my own -dV fast charger will charge two cells as a single "unit" and I wonder what happens when one cell will hit its -dV point a long time before the other cell does. Does the -dV point get masked and overlooked?
In fact if I put four AA cells in my charger then it seems to treat all four cells as a single "unit" and aims to detect -dV from all four as a whole.
Surely this arrangement must often lead to overlooking the -dV point? Then the large currents used for the fast charging would now make the cells go well into overcharge until maybe a temperature sensor detected the situation. Ugh! Overcharging NiMHs is a good way to spoil them.
Am I overlooking any important factors which mean it is not as gloomy as it may seem?
Or maybe these "2 cell" and "4 cell" -dV fast chargers are just too crude to consider using if you want your NiMH cells to last?