Group 41 batteries come with or without the tube connections for venting. The Exide doesn't have the handle and side pieces and fits in the battery compartment much better. You need to spec when buying. For the Westfalia the engine battery box has a screw on gasketed cover and is vented into the wheel well. The aux compartment on the driver's side can be set up the same way with some sheet metal work. Personally, a flammable gas detector which is a good idea with propane will keep you safe and it really is only an issue if you are charging batteries while sleeping. At 13.8V stock charging voltage you're not going to off gas the battery unless it is failing. 

The 850 CCA Diesel battery is a group 49 and it is longer than the 41. BTW a group 42 is smaller than the 41. 

Dennis
 

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Raceing Cajun
Sent: Saturday, July 4, 2015 10:13 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Batteries and solar panels!

You might try a "Group 41" battery. Came with Audi 5000's under the rear seat, so the gas's needed a vent. Fits the Vanagon box, and has the same post arrangement, as a Group 42. The Diesel version has 850 CCA, and will spin a 2.1 pretty good. You will need to drill a hole for the hose, be sure and paint the edges, and use a grommet to seal it from the elements. Aim your drill well !!!

Skipper

>Very few available batteries have the vents on the ends to vent 
>hydrogen gas to the outside of the van.  Frankly, I don't even remember 
>the brand I have, I would have to open up the compartment and look.  
>But it has the vents.