Date:         Fri, 26 May 2000 09:39:38 -0400
Reply-To:     David Beierl <dbeierl@IBM.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Beierl <dbeierl@IBM.NET>
Subject:      Re: wiring auxiliary battery
Comments: To: Puzerewski <Puzerewski@EMAIL.MSN.COM>,
          Richard Ferguson <fergusrh@YAHOO.COM>
In-Reply-To:  <004301bfc6ee$7caea680$be9a183f@amy>
Content-Type: text/plain; charset="us-ascii"; format=flowed

At 04:43 5/26/2000, Puzerewski wrote:
>I wonder the same, although i know it is probably answered many times.
>
>I purchased the Hella aux battery kit from Bus Depot, and after reading the
>directions said HUH???
>
>I have a westy, and the fridge relay is in place.

The relay ordinarily replaces the fridge relay and is wired so that the
batteries are connected in parallel while the engine is running.  The wire
between the batteries really should be fused or have a circuit breaker,
though I imagine there are a great number of such installations where it is
not.  Starting with our (and many others') boat where the batteries are
paralleled with 2-ga battery cable and a 300-amp manual switch.

IF YOU CONNECT TWO 12V BATTERIES IN SERIES, YOU WILL GET A NASTY SURPRISE
WHEN ONE OR BOTH EXPLODE.  A fuse will prevent the explosion, but it's
still not what you want.

Ordinarily the fridge is then connected straight to the aux. battery -- but
personally I would consider retaining the fridge relay and using its output
to drive the charging relay.  This means that the fridge still won't run on
DC unless the motor is running, but it also means that you won't come back
in a few hours and find the aux battery flat b/c you forgot to shift the
fridge to gas.  Your choice.

Everything I've ever seen from Hella came with a wiring diagram -- is this
kit different?   I'm a bit reluctant (as well as lazy) to give pin-by-pin
directions because I have a sort of feeling that people connecting big
batteries together should actually *understand* what will happen and not
just put things together by rote.  And the fact that the question arises
about series vs parallel makes me nervous...

david

David Beierl - Providence, RI
  http://pws.prserv.net/synergy/Vanagon/
'84 Westy "Dutiful Passage"
'85 GL "Poor Relation"