Rechargeable AAA batteries. Do the NICD and NIMH require separate chargers?

Answer 1

Generally a NiMH battery charger will charge NiCd batteries but not vice versa (the old NiCd battery chargers won't work).

The best thing to do is check out the packaging or the specifications online.

Some of the newer NiMH batteries are mfg specific. For instance, IC3 batteries from Rayovac will ONLY charge on IC3 chargers and not any other ones even though they are NiMH.

Answer 2

The problem is that NiMH batteries do not tolerate overcharging as well as NiCd batteries. I assume that the BQ-4C is just a "dumb" charger that will charge the batteries at 240mA forever. This is not too much of a problem if you always completely discharge the NiMH batteries and are diligent about taking them out of the charger after 14 hours or so. But if you make a habit of leaving them in the charger for extended lengths of time, they will not last nearly as many cycles. Some cheap (not the best!) NiNH chargers are like your old one except that they use a timer to limit charge time. If you make a habit of charging mixed NiMH batteries with unknown charge states, you can help the batteries out by discharging them prior to recharging. Discharging NiMH batteries to zero volts is not good for them either, but you can discharge them through a 14001 type diode in series with a 2 or 3 ohm resistor. That way they will stop discharging at about 0.7 volts.

Answer 3

Not necessarily. It all depends on the individual charger. Tandy & Dick Smith stores sell a 'Digitor' branded one that charges both and will do from a AAA to a size D battery..its about $30