[Shop-talk] dewalt battery charger testing

[David Scheidt]

On Wed, Dec 22, 2010 at 10:25 AM, john niolon <jniolon at bham.rr.com> wrote:
> I'm having trouble charging Dewalt batteries... some it may be old
batteries
> but I'm wondering if my one hour charger is dying... B  Dewalt 9107 B one
hour
> charger B  when I put a meter across the contacts down in the charger I read
NO
> d.c. voltage. B although the battery is getting warm and slowly taking a
> charge... I had a completely dead 12v battery and started charging it with
a
> hotter power supply 26volt B for a few minutes... it came up to about 8
volts
> and I then stuck it in the 9107.... B 4 hours later it's up to about 10
volts
> ??? B  This is a 2.8 amp charger and should do better than this...
B discounting
> a bad battery pack... how can I test the charger ???
>

As i recall, that's a multi-voltage charger.  The batteries have
terminals that tell the charger which voltage they are, depending on
how they're wired.  I have no idea what the pinouts are, but I'll say
this: if it works at all, it's fine, and your battery is shot.  (There
are basically two failure modes with this sort of battery charger:
dead, and fire.)  Test it with a known good pack.  If you don't have a
known good pack, tis the season for good deals on new drills...


--
David Scheidt
dmscheidt at gmail.com