Don't bother unless you do both sides. If that wire shorts out the auxiliary
battery will have no problem smoking it. Only real protection for the wire
is to fuse both sides. Since the real power source for charging is the
alternator that is really where the charge line should start or at least
upgrade the wiring from the alternator to the main battery cable.

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Don Hanson
Sent: Saturday, December 11, 2010 1:20 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Mega-fuse? (between batteries)

  I'm cleaning up 'loose ends' and dangerous 'temp' stuff in my van.  I just
remembered that when I installed my auxilliary battery, I left it without a
fuse between the regular starter battery and the new Aux battery under the
driver's seat.   So I have, right now, a wire (about #4-6? dunno sizes very
well) running across to the driver's side directly from the positive
terminal of my primary starter battery to one of those mechanical relays..
I took good care to protect this big hot wire from chafing but it has no
fuse yet.  So I found a fuse at Shucks Auto...a "Little Fuse" Mega..rated
for 175amps.  It's also marked 'Slo-blo 32 v."   Essentially it is a copper
link, meant to be bolted into the system.  I plan on putting this at the
positive terminal of my regular battery and running the hot wire from that
on to the auxillary battery...

  Will this save me from an electrical fire should that supply wire somehow
short out? These type 'fuses' do come in other ratings, too.

  Don Hanson