Should warn you that these 12v lamps are like ordinary mains halogen lamps in many ways – the life expectancy of them is considerably extended if you under-run them by about 5%. This effect is most marked on the mains ones, but applies to all of them. The reason for the warning is that if you over-run them, the life shortens by a very considerable amount!
So it rather depends on your battery charger. But most of them produce about 14-15 volts, and that represents a considerable overload for a halogen lamp, so you really wouldn’t want to run it for very long like this.
You are much better off with a known-quantity 12v supply with these lamps. Even better off still if you make it a DC supply rather than an AC one, because that way you absolutely guarantee to get no strobing from lathe chucks – a very real possibility with AC lamps. The worst effect of this (although pretty rare) is to have a chuck revolving at 50, 100 or 200 rpm appearing to be motionless!
Edited By Steve Garnett on 13/09/2011 22:02:40