On Tue, 16 Apr 2013 18:36:52 +0700, J.B.Slocomb
wrote:

On Tue, 16 Apr 2013 03:21:00 -0700, mike wrote:

On 4/15/2013 7:06 PM, J.B.Slocomb wrote:
The charger for my old battery drill has died and I'm trying to
resurrect it. There are three connections to the battery, two larger
connections labeled "+" and "-" and a third connect, smaller and
labeled "T". The plus and minus connections are easy enough but what
is the "T" connection.

As some of the components in the charger are unmarked I have been
thinking of just connecting a 12 volt charger to the battery
connections and am wondering about what to do about the "T"
connection.

DO NOT CONNECT A RANDOM CHARGER TO THE BATTERY PACK.
If you want to build a charger, you need to know a LOT more
about batteries than you appear to know.

The T connection is probably related to temperature
and can be configured to operate in several different ways.
And it MUST be connected as designed for that system.

What usually happens is that one or more of the cells short.
That increases the current and overheats the transformer
and the thermal fuse inside the transformer opens up.

It's likely that you need a new transformer and a new battery.
Even if you get a new charger of the proper type, your battery may
kill it too.

I have a lot to say on the subject, but unless you want to become
a battery engineer, you're better off buying a new drill.

If by "Transformer" you are referring to the charger it is a bit more
than a thermal fuse, it was several capacitors that died and leaked
all over the circuit board, a resister that apparently overheated
physically broke and two three legged devices one of which is a
transistor, the other is unmarked.

I charged one of the two batteries, using an automotive 12 volt
charger and once charged the battery appears to have normal capacity,
at least measured by number of holes it can drill.


Look on ebay for another charger.

Remove 333 to reply.
Randy