Re: The hydrogen gas- is it that there's a very small amount so that it sort
of forms a 'halo' just in the immediate vicinity of the battery? Every time
I read about this, I get this image of somebody in the passenger seat
lighting a cigarette... well you get the idea.

What's the scoop?

Cya,
Robert

----- Original Message -----
From: "Bruce Nadig" <motorbruce@HOTMAIL.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Tuesday, September 21, 2004 6:46 PM
Subject: Re: Q: Battery Disconnect Sequence?

> The answer below is close to the truth, but not right on.
>
> True, the body of the vehicle is negative. Chances are that any tool (such
> as a socket or box-end wrench) you would use to loosen the battery
> terminal
> would be metal. If that metal tool was being used to disconnect the
> positive
> terminal first and it hit the body while doing so, things would get real
> exciting real quick. I have heard stories of mechanics even having their
> rings (ie. wedding rings) getting "welded" between a positive and negative
> connection.
>
> If you take your metal tool and disconnect the negative side first, you
> won't have a problem if your wrench touches the body because the body is
> just an extension of the negative side of the electrical system. If your
> negative is still connected and you are attempting to disconnect the
> positive terminal and that same tool contacts the negatively charged body,
> at a minimum, you will get a large spark. Being so close to the battery,
> that spark could very well ignite any hydrogen gas that has been
> discharged
> from the battery (that is why you don't connect your negative cable on
> your
> jumper cables to the battery).
>
> What is stated below isn't quite true. Once the positive cable is
> disconnected from the battery terminal it no longer has a charge in it, so
> it doesn't make any difference if it hits the negatively charged body
> (which
> is no longer negatively charged, by the way, because there is no longer a
> complete electrical circuit). You could, in fact, safely put that positive
> terminal to the negative terminal to the battery and nothing would happen
> so
> long as there is nothing connected to the positive terminal of the
> battery.
>
> Make sense?
>
> Be Safe.
>
> Another electrical tip: When giving someone a jump start, make sure that
> the
> vehicles that are involved in the jumping process are not touching in any
> way.
>
> Cheers,
> Bruce
> motorbruce
> motorbruce@hotmail.com
>
>
>
>>From: Jim Felder <felder@KNOLOGY.NET>
>>Reply-To: Jim Felder <felder@KNOLOGY.NET>
>>To: vanagon@GERRY.VANAGON.COM
>>Subject: Re: Q: Battery Disconnect Sequence?
>>Date: Tue, 21 Sep 2004 19:56:31 -0500
>>
>>It's not the sequence.
>>
>>On any car but old english ones, the negative is the ground, and it's
>>strapped to the car frame somewhere. So you could say that everything
>>on the car is "negative" that is connected to the frame by even a
>>fastener. If you take the positive cable loose, it stands every chance
>>of hitting one of these negative frame or body members (engine too,
>>everything) and you'll get a big hot spark in the best-case scenario.
>>
>>Letting the negative cable hit anything but the positive terminal, and
>>nothing will happen.
>>
>>Jim
>>
>>On Sep 21, 2004, at 8:46 PM, Jack wrote:
>>
>>>Ok, I need help.
>>>
>>>In several manuals, including a Ford Owner's manual (forgive me) and a
>>>Haynes repair manual, I've noticed that they specify that the negative
>>>battery cable must be removed first when disconnecting the battery.
>>>Why???
>>>
>>>What possible difference can it make which terminal is disconnected
>>>first???
>>>  When I first ran across this, I ignored it as a harmless error by
>>>someone
>>>who didn't understand electrics, but now I find it in "professional"
>>>references.
>>>
>>>Help!  What am I missing?
>>>
>>>//Jack
>>>