This is not a good idea. While it might work for a while, you have to make
absolutely certain that break occurs before make. Secondly, you would have
to use contactors that can handle 200 amps. They are very expensive and in
use, would be in serious danger of being trashed. Perhaps a 48 volt charger
is MUCH cheaper.
Steve

"CS" wrote in message
oups.com...
I am looking to make a 24v/48v Series/Parallel Switch so that I can
charge 4 12v batteries at 24v 65A and use them at 48v 200A and wondered
if there was any pointers out there on how to do it - probably with a
few DC contactors.

TVMIA