Date:         Fri, 9 Jul 2010 11:24:30 -0700
Reply-To:     Jeff Schwaia <vw.doka@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Jeff Schwaia <vw.doka@GMAIL.COM>
Subject:      Re: battery compartment
In-Reply-To:  <4c375984.df0ae50a.650c.2a7b@mx.google.com>
Content-Type: text/plain; charset="us-ascii"

My favorite "exploding battery" incident happened to the body shop next door
to the repair shop I worked at in the early '80s.  Their "gopher" hooked up
the battery charger to a BMW that had just rolled out of the paint booth
earlier that day.

Unfortunately, he hooked up the leads backwards...

Fortunately, he had to hook up the charger to an extension cord and was 50'
away when it went kablooey.  I was surprised how loud it was.

Can't remember if the gopher kept his job or not, but I do remember that BMW
going through prep and paint one more time.

Cheers,

Jeff



-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
David Beierl
Sent: Friday, July 09, 2010 10:11 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: battery compartment

At 11:23 AM 7/9/2010 Friday, Dave Mcneely wrote:
>For those who really know, are "maintenance free" batteries really
>so?  Seems they must evaporate some water, but it seems not routine
>any more to add distilled water to a battery.

Low-maintenance is a more correct appelation.

>   Vent caps pry off, too, rather than screw off, so potential to flick
acid.

You have to work your way around the perimeter, prying incrementally,
so if you have the awareness of say one of the lower chordates the
cap won't jump off.

>   Eye protection when working with batteries, for sure.

I am personally acquainted (through the intertubes) with either three
or four people who have experienced a rapid-disassembly-event while
working with a battery (and none of these batteries were
frozen).  One heard the battery rumbling and left the premises; one
was sixteen and promptly hauled under the hosepipe by the men
standing around, neither of the other two suffered serious
injury.  But what I used to think was a vanishingly rare occurrence
turns out not to be.  Uncommon, yes.

VW in 1984 was using a sealed box with gasketed lid, venting to the
outside for the main battery and a spring-latched door for the
auxiliary (Konsistency?  Bah!  Let ze Americans wunder.);  by my '89
both sides were the swinging doors, open at the front to all the
passing breezes.


>After-market batteries seem never to be sealed units, like some that
>come with autos.  Reasons?

Aftermarket batteries are anything you want and are willing to pay
for.  Conventional with individual cell caps, low-maintenance with
caps in sets of three, "sealed" with at least three types of internal
construction: flooded cells, AGM (absorbed-glass-mat) and gelled
electrolyte.  Within these construction types, the type of plate also
varies drastically, from heavy solid plates for true deep-cycle use
to light-weight grid plates with powdered material pressed into the
grid for high-current float usage (i.e. starting service, where the
starter draws enormous current very briefly, using very little of the
battery's capacity, and the battery remains in a mostly-charged
condition throughout its service life) and everything in
between.  Generally speaking, the denser a battery is the closer it
approaches the deep-cycle type such as those made by Rolls.

>  Pros and cons of the two battery types (sealed vs. "maintenance
> free")?  Certainly, a battery that is not capable of spraying acid
> around would have at least that big advantage.

All lead-acid batteries are capable in the wrong circumstances.  The
sealed types have vent valves to relieve overpressure -- it's just
that if you overcharge them and the water vents out you have no way
of putting it back.  However you can operate them in any position and
under normal circumstances they will stay clean and dry outside.  The
major tradeoff is that if you abuse a sealed battery you get to throw
it away, instead of putting back the water you gassed off and
recovering some of the battery life.  And "abuse" is construed more
narrowly for the sealed types.  No, that sounds right but it
isn't.  It's construed more *widely* i.e. they are easier to abuse.

If you are aware, educated and willing to spend big $$$ in equipment
and battery first cost and weight, and further spend noticeable brain
cells (and equipment) in managing the system over its service life,
you will undoubtedly have longer service and a lower overall cost of
ownership (of a house battery system) with AGM or gel batteries.  If
you're not willing or able to do all the above then AGM or gel are a
waste of your money -- get the cheapest combined-usage battery you
can and replace it often (on Scamp we had to replace batteries every
three years or so until we bit the bullet and got serious about the
charging and monitoring systems).

For a starting battery operated in float service, that is for normal
starting/running of the vehicle, I would personally avoid AGM or gel
and pick -- probably -- the low-maintenance type.  If that same
battery is to serve as a house battery for other than casual
low-drain camping I would get a combined starting/deep-cycle type and
think seriously about a three-stage regulator.  On Dutiful Passage
('84 Westy) we used a regular starting battery and standard regulator
for camping use, but our current draw was minimal -- couple amps for
a few hours a day, and our stays were short.

Now I'm going to do what I should have been already, and finish
packing and leave for Mauch Chunk Lake Park in the town of Jim Thorpe
PA, there to mingle with a herd of Vanagons and Vanagonauts.

Yours,
David