You would be surprised at how little hydrogen is required for a flammable mixture. Our forklift charging areas have hydrogen sensors that activate exhaust fans and sounds alarms. Fans speed up at 1% and the alarms go at 2%. My motor home has 4 golf cart and two engine starting batteries in a compartment completely outside the living space.  When the 100 amp charger gets those batteries into the off gassing stage the Propane detector inside goes off. 

So charge you batteries with a 4 stage charger while sleeping with everything closed and light your stove first thing in morning for coffee. 
Yes, I'm being a wise guy but there are reasons that things have to done a certain way. 

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Rocket J Squirrel
Sent: Wednesday, August 10, 2011 10:50 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: General Question On Battery Venting

Jeepers. You guys think I'm a worrywart. No one is going to accumulate enough hydrogen in their van to cause a fire or explosion. Our charging currents aren't high enough, our batteries are too small. That stuff will float out of the van like a ladyfart in a breeze at a picnic.

--
Jack "Rocket j Squirrel" Elliott
Bend, Ore.
1984 Westfalia. A poor but proud people.
1971 "Ladybug"-brand utility trailer ca. 1972 from a defunct company in San Clemente, Calif., now repurposed as The Westrailia.

Sent from my kitchen.

On 08/10/2011 07:30 PM, Dave Mcneely wrote:
> The vents open under the vehicle, don't they?  Looks to me like they 
> do.  And with good fasteners and the gasket in good shape, the top of 
> the box is sealed.  mcneely
>
> ---- craig cowan<phishman068@gmail.com>  wrote:
>> even with a sealing lid, won't the gasses just vent out to under the 
>> seat and up that way?
>> It's just not at all sealed.
>>
>> -Craig
>>
>>
>> On Wed, Aug 10, 2011 at 9:39 PM, Dave Mcneely<mcneely4@cox.net>  wrote:
>>
>>> Thanks, TJ.  But not all campers came that way.  The Campmobile, 
>>> with full camping outfit, did not.  I suppose when you say, "dual 
>>> batteries under the seats," that you mean the starter battery under 
>>> the passenger seat, and the "house" battery under the driver's seat.  
>>> But my camper, with the start battery under the passenger seat, 
>>> definitely has vents and a gasket on the lid.  I have made it a 
>>> point to refit the lid with new fasteners so that the seal works.  
>>> Now I will pursue fitting a hose so that the vents work as designed.  
>>> mcneely
>>>
>>> ---- TJ Hannink<tjhannink@YAHOO.COM>  wrote:
>>>> Vanagon Campers, like my '87 Wolfsburg Edition came from the 
>>>> factory with
>>> dual batteries under the front seats. Neither compartment is sealed 
>>> or vented.
>>>> TJHannink
>>>>
>>>> On Wed Aug 10th, 2011 1:00 PM CDT Dave Mcneely wrote:
>>>>
>>>>> ---- Loren Busch<starwagen@gmail.com>  wrote:
>>>>> And I also have a vague
>>>>>> recollection of seeing a hole in the aux battery compartment to 
>>>>>> allow
>>> the
>>>>>> same kind of vent hose to be installed.  But of note is the fact 
>>>>>> that
>>> the
>>>>>> cover for the aux battery under the drivers seat is NOT sealed 
>>>>>> but
>>> hinged
>>>>>> with a latch, not held down by screws like the starting battery.
>>>>>
>>>>> Is that because on the camper, the box under the driver's seat is 
>>>>> not
>>> really intended as an auxiliary battery box?  Or is it?  Do those 
>>> Vanagon models that came from the factory with a battery there have 
>>> a gasket and a hose?
>>>>>
>>>>> --
>>>>> David McNeely
>>>
>>> --
>>> David McNeely
>>>
>
> --
> David McNeely