Date: Fri, 1 Oct 2010 14:36:37 -0500
Reply-To: mcneely4@COX.NET
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Dave Mcneely <mcneely4@COX.NET>
Subject: Re: Battery placement alternatives
In-Reply-To: <09CA13A4-A1C2-47A5-B5AE-0BCCFB811737@shaw.ca>
Content-Type: text/plain; charset=utf-8
Alistair, you probably know enough to correct any error that I commit here. My understanding is that all lead acid batteries produce hydrogen gas during charging due to electrolysis of water. The amount of hydrogen depends on the charging rate, but even routine charging during driving would produce some hydrogen gas. Battery explosions are most commonly explosions from within the battery, due to gas accumulating inside, but gas can be present any time charging is going on. The most common ignition source for a battery explosion is a spark, which is why jump starting instructions specifically provide for making the last connection at a point distant from the battery.
I don't think any of us think that a battery explosion is a likely event in our vans. Safety precautions are taken to make even unlikely events less likely.
When one jump starts a vehicle, the donor vehicle is supposed to be run at faster than normal idle, to make sure the donor battery is not depleted during the donation. So, it is charging as if the vehicle is being driven. It is also delivering charge into the recipient battery during the brief time of the donation.
Could a battery explosion take place then, and is it more likely with a vanagon with its battery in an enclosed box inside the vehicle than with a vehicle with its battery in an open engine compartment? Of course the battery box is open and the van is open during the operation, but the gas has less opportunity to dissipate than it does with an open engine compartment. And the precautions that are recommended in jump starting instructions are given for vehicles with engine compartment battery placement.
BTW, just due to no need, I have neither given nor gotten a jump with my vanagon. But this discussion has prompted me to consider the proper location for grounding. I suppose the best place would be on a frame member under the vehicle, since the usual grounding locations in the engine compartment are all too far away. Where would you ground the jumper cable on a vanagon?
Do you know how many vehicle battery explosions happen during a year? I have no idea.
David
---- Alistair Bell <albell@SHAW.CA> wrote:
> I would bet that any venting to the outside is not for hydrogen gas,
> but rather to remove any sulfuric acid fumes from immediate area, to
> reduce corrosion of nearby parts.
>
> you are not going to get an explosion under the seat from the small
> amount of hydrogen gas produced by the battery. A battery can explode
> from within if hydrogen and oxygen are not allowed to escape, but
> that is different than the fear of vented hydrogen combining rapidly
> with the co-produced or atmospheric oxygen, in the space under the
> seat of a vanagon. Hydrogen and oxygen are the products of
> *overcharging* lead acid batteries.
>
> its a different order of magnitude if you have a vast bank of
> charging batteries, ie a diesel electric submarine.
>
> alistair
>
>
>
>
> On 1-Oct-10, at 10:43 AM, Loren Busch wrote:
>
> RE: Stock battery venting
> I'll try to get a picture and post a link to it.
--
David McNeely
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