flydiver
(flydiver)
7
Essentially to charge NiMh, you pretty much have to over charge it. d-t-a has it correctly, the termination method is entirely different. Depending on the battery condition (old/poor batteries make it harder to get right), the level of charge (too high or too low), and the charger termination method it is entirely possible to:
- terminate too soon > getting a low capacity; sometimes very low as it stops almost immediately.
- terminate too late > showing high capacity; more usual as the battery gets older with higher internal resistance.
- or in some cases not terminate at all > showing whatever capacity was put in until you finally stop it (a ridiculously high capacity)
Discharging NiMh from full to a known stopping voltage is the only reliably accurate way to test them. Even that has issues if you use too high a discharge current on a battery that can’t handle it.
It’s actually harder to charge NiMh properly than Li-on. It’s just when you screw up the consequences are not as nasty (usually).