Ask PYS: Power

Pat, on May 02, 2012 asked:

I have a friend that is trying to get 12V from a 36V battery bank (i.e. he has six 6V batteries in series). He needs to get 12V for a heated vest (an accessory). Is there a diode or some contraption I could use after two batteries, and pull 12V from the bank? We would use one of the Newmar DC to DC converters, but they're out of his price range. Do you have any ideas?

There is really only one solution to this question. Unfortunately, you need a 32V to 12V converter. Otherwise he should consider getting a dedicated 12V battery and small charger if he doesn't like the pricing of the converter. You absolutely cannot tap into a 12V cell and discharge that cell. We have seen it numerous times and it destroys the 12V cell prematurely, and leaves the whole 32V cell ruined.