Most auto batteries give off a little bit of hydrogen gas-not bad when 
the battery is outside, but not fun if it is inside the bus.  There are 
some kinds of deep-cycle batteries out there that do not give give off 
gas.  They are gel-cell batteries.  They also cost a lot more than 
regular batteries, but the price is obviously worth it.

There is a recent article in Homepower Magazine about a person that 
installed a solar system in his Vanagon, and used a gel-cell battery.  
The issue is for December/January, so should still be around.  It is kind 
of hard to find the mag, but it lists his email address if you want to 
ask any questions.  Homepower is on the web at 
http://www.homepower.com/hp is you want to take a look at it online.

Good Luck,

Craig

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Craig Standley				1974 Volkswagen Westfalia; The Cow Van
University of Washington
Physics Major				"Heaters?  We don't need no stinking
cstand@u.washington.edu			 heaters."
http://weber.u.washington.edu/~cstand    
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