I purchased a 12V Makita drill (6216D) about 2 years ago. It came with
two of the gray 2.2Ah Ni-MH batteries and a charger (DC1411). From the
very beginning, it did not seem to me that the batteries were holding a
charge very well. I could charge a battery until the green light came
on, remove the battery put it in the drill ... and come back 2 weeks
later and there was very little power left in the "fully charged"
I previously owned a Craftsman Professional 9.6V drill with NiCad
batteries (which I suspect were nowhere near 2.2Ah) ... and it would
hold a charge for several months. I think I've read that Ni-MH
batteries will lose their charge quicker than NiCad batteries ... but I
wouldn't expect a "fully charged" battery to lose most of its charge in
My problem now is that I can't seem to get either of the Makita
batteries to fully charge. I've tried only leaving the battery in the
charger for an hour ... and I've tried leaving it for a week. Neither
way seems to fully charge the battery. One thing that seems strange ...
after charging a battery for a couple hours, I can remove the battery
... wait a few minutes ... and then plug it back in to the charger ...
and the blinking green light turns red and stays red like it is doing a
full charge cycle. (I have not timed it to see how long it stays red,
although I suspect it's not very long.)
So ... my questions:
(1) could the charger have been "bad" from the very beginning?
(2) is there anyway to rule out the charger as the problem with a v/o
(3) is it more likely that the batteries are "bad" (and maybe were from
(4) what's my best course of action to diagnose my problem?
One last question ... does it harm the battery or the charger to leave
a "fully charged" battery connected for weeks?