Date:         Thu, 13 Dec 2001 13:29:50 -0500
Reply-To:     "Warner, Jeff (DSIO-MS)" <Jeff.Warner@DSIO.DLA.MIL>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         "Warner, Jeff (DSIO-MS)" <Jeff.Warner@DSIO.DLA.MIL>
Subject:      Re: Battery Isolators vs. Relays

Well Dang!  Just when I thought I was okay with the relay idea.  Now we're
back to my original question.  To your corners!  Isolators on the left.
Relayers on the right.


Date:    Fri, 14 Dec 2001 02:07:45 +0800
From:    Tim Hannink <tjhannink@EARTHLINK.NET>
Subject: Re: Battery Isolators vs. Relays

The relay setup works great until the auxiliary battery develops an inter=
nal short. The batteries attempt to equalize, but since the internal resi=
stance of one battery is zero, the other battery can only get weaker. The=
 alternator won't charge either battery since they are connected in paral=
lel when the engine is running. Eventually, both batteries need to be rep=
laced.

Why would the auxiliary battery short out? Since the refrigerator in the =
Wolfsburg Camper model runs on only 110VAC and 12VDC, some people (includ=
ing me) tend to leave it plugged in while parked, totally dis-charging th=
e auxiliary battery. The fridge draws 8 amps/hour and will discharge a ne=
w starting battery in 6-7 hours, the first time. Every time the battery i=
s deep discharged after that, you loose about 25% of its capacity. My 1 y=
ear old battery can run the fridge for a little over an hour right now wi=
thout the engine running. Eventually, the battery will short out internal=
ly and not hold a charge.

The obvious solution is to install a deep-cycle battery in the auxiliary =
battery position. My concern is having dissimilar battery types wired in =
parallel and the effect it will have on the batteries. I will be installi=
ng an isolator with the deep cycle battery(s) to keep this from happening.

Another solution is to rotate the batteries every couple of months.

Or install all deep cycle batteries.

Tim Hannink
Goldibox - 1987 Vanagon Camper, Wolfsburg Edition
Winter Park, Florida
http://home.earthlink.net/~tjhannink/

--
 <<...OLE_Obj...>>
"Racing is life, anything that happens before or after, is just waiting!"
Steve McQueen as Michael DeLaney (LeMans 1970)