Mike Atkinson {see sig for return address} wrote:
Due to a freak (I hope!) occurrence, about 6 months ago many mains
adaptors in our house were knocked out of action. Our local power
supplier arranged to have these replaced, but I unfortunately forgot
about an adaptor located in our garage...

I discovered recently that the charger for my Black & Decker
drill/driver (HP9096) is now fubar. Before I threw this away I was
careful to note the stated output voltage and current rating, but didn't
note the polarity (if it was indicated?). Now I've purchased a generic
mains adaptor that can supply sufficient current of the correct voltage,
but I don't know the correct polarity (positive or negative 'tip'
according to the new adaptor's instructions). Does this matter?

I've checked the drill's supplied instructions, and the B&D website, but
am unable to find this information. For some unknown reason I kept the
end connector of the B&D charger, so I can determine that inner
connector corresponds to the wire with a white stripe running down it's
length. Is this stripe to intended to identify the negative feed?

Please could someone put me out of my misery. Does the polarity matter?
I'd like to know before I leave my driver charging during the day - I
have visions of exploding batteries!

Many thanks in advance for any advice,
Mike


Mike,

Yes polarity may be very important. It may just not charge (if B&D put
a protective diode in) or it may bang spectacularly. That end connector
is going to be useful in diagnosing which way round, but you will need a
test meter.

Try this:

Identify which wire is which on the old connector using the meter on
resistance range.

Connect the wire from the OUTER of the old connector to the outer of the
new charger connector using tape, a wooden clothes peg, etc leaving the
two 'inners' isolated and unconnected. Plug old connector into the
drill/charging base/battery and the new charger into the mains.

Check voltage between the two inner connectors with the meter set to a
DC voltage range of about 30 volts. A paper clip is good for getting
into the hole of the new connector.

Reverse polarity of the new supply and check voltage again.

In one case you will get a high reading of supply voltage PLUS battery
voltage (for this 9.6v drill expect about 20 volts) - this is the WRONG
way round.

In the other you will get a lower reading (about 3 volts) being the
difference. This is the right way round.

Good luck!
Phil