I have a B&D firestorm HP431 drill. The charger has stopped working.I have an old charger which is the same spec except it is 3.3 va instead of 3.2 va. I dont think this will be a problem. However I don't know which is the positive terminal of the battery . I need this to check the conection between the old plug-in transformer and the B&D battery charger holder is the correct polarity.

SOURCE: I have a Black and Decker 7.2 V cordless drill

Center pin is generally positive - outer ring is negative. But you can use a 9v charger just as easily; in fact, the one supplied with the cordless drill is a 9.0v, 200mA output charger.

SOURCE: i need a battery for a metabo sb impuls hammer

I saw them in the latest Metabo leaflet. They are serious producer and they shoudl keep spare parts for few years after they discontinue some product. Try to call to Metabo in your country. Juraj

SOURCE: Will a 12 volt slide

This close to father's day you should be able to buy a new drill for about the same as a battery. The 12v would overheat the motor if you ran it for an extended period.

SOURCE: what is the polarity of a 12v Black & Decker Drill?

centre pin on plug socket is usually positive...
think I would **** it and see ....if the replacement charger has a charge light it will probably not light if you have reversed polarity. Had the same problem with VHF portables ...I just cut the wire on new charger and tried both options ..reconnected and a bit of tape...voila.
There is little danger to your drill from getting it wrong as long as a the timing is relatively short.