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Will the 15 minute chargers for AA NiMh batteries give me as much performance as the slow rate chargers that take 5 to 12 hours to charge the battery?


Yes and no. If you charge the battery just until the charger indicates that it is done with the fast charge, you will have charged for 15 minutes or less. A reasonable person that hadn't read the manual, (like you and me), would think that it is completely done. In fact, it is only changing from the high charge rate to a trickle charge. If you stop charging at this point, you will get about 90% of full performance out of the battery. If that is all you need, then there is no reason not to just do a 15 minute charge. To get the last bit of charge into the battery, however, you will have to let it remain on the charger for another hour or a little more. It is still pretty remarkable that you can get a nearly fully charged battery in only 15 minutes.

The reason for the slight undercharge is that the battery gets hot from having charge crammed into it in such a short period of time. The charging current is over 8 Amps. That's why the 15 minute chargers actually blow cooling air over the battery and the charger's electronics.

Hot NiMh batteries do not hold as much charge as a room temperature battery. So it is necessary to allow the battery to cool down a bit before the last bit of charge can be put into the battery using a trickle charge of a fraction of an Amp.

Posted 1 year agoby LectroAdmin