What makes the powdery white or gray deposits on some of the metal parts
around the van batteries?  Actually my Vanagon stays pretty free of
the deposit, but we inherited a 2.5 Subaru Forester that gets it bad.  We
stored it down in Californa during the summer and use it as a vacation
car. We opened it, around Xmas time to find the battery(disconnected but
fully charged)  was covered with a whitish powdery deposits, heaviest on the
hold-down ring and the clamps, but also under the batt on the tray.  I
bought another new battery...and cleaned everything up with baking soda,
like a good little car guy before installing that one...

  We brought it back to the NW...(shhhh...I'm hoping to finesse it (the
motor)  from my wife, eventually..for use in a ....) and I just noticed that
the hold-down clamps and the retaining ring is again almost pure white with
a fine powdery substance...Both my Ford Diesel trucks do the same thing, but
to a lesser degree.

  What the heck is this stuff and how do you prevent it forming?

  Don Hanson