On Sep 22, 10:40 am, dpb wrote:
wrote:
Hi!

I just bought a Makita BDF452HW about two or three months ago and
having a problem charging the battery. The one battery charges fine,
but when I put the other battery in, the charger lights flash green
and red alternately. From what I can see, this means that the battery
is broke.

...

Battery infant mortality is a fairly common problem. Should be
replaceable under warranty. Normally box retailers don't do warranty
service but you might get them to trade the whole thing out if you try.
Otherwise, whatever Makita says for warranty service rules...

--

Its easy to kill a battery, a Nicads are discharged just when the
drill slows, running it down more can reverse a cells polarity, it is
also best to let a pack rest a day before recharging constant use is
hard on it.