Date:         Thu, 9 Feb 1995 10:13:32 -0800 (PST)
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         David Schwarze <schwarze@superc.nosc.mil>
Subject:      Re: Westy auxiliary battery (why not keep it going)

rathkem@admin.ci.seattle.wa.us writes:
> 
>  The Ideal situation would be to have a dual output alternator (one with two 
> windings) connecting to seperate circuits: one would be the regular van 
>battery. the other would be wired to three golf cart batteries (instead of the 
> deep cycle battery).  I think the would be wired parallel, but I am not sure.

This is not ideal because most of the time, the output of one half of the
alternator will be wasted charging the almost-full starter battery.  Also,
what is the fascination with three golf cart batteries?  :)  You are the
second person that has mentioned this.  The golf cart batteries I have seen
are all 6 volts, and therefore the third one would be essentially useless.

> This configuration gives a complete separation of the two battery systems.  
>The problem with the deep cycle batteries is that they are designed to drained 
>completely and then recharged completely, the golf cart battery arrangement is 
> ideal for shorter, medium to light usage and then topped off with a recharge.

Deep cycle batteries are not designed to be drained completely.  I think
the manual for mine said to avoid discharging more than about 75 percent,
and preferrably 50 percent.  Anything more will greatly accelerate the
death of the battery.  The golf cart batteries are designed for heavy
current draw over an extended period, similar to a marine/rv battery.
Golf cart batteries _are_ deep cycle batteries, just like the marine/rv
batteries, except that they have even thicker plates (so I'm told) which
accounts for their extreme mass and longevity when compared to other types
of batteries.

> ** As an aside: in putting together my latest fire truck project I used a 120 
> amp dual output alternator one side connected to the truck battery, and the 
> other side connected to (2) 8d auxillary batteries.  The truck batteries are 
> continually topped off with a shore power connection.  I used the deep cycle 
> because those emergency lights suck the power like nothing else.

Is that 120 amps per side, or 60/60?  In any case, it sounds expensive.  :)

-David

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David Schwarze                  '73 VW Safare Custom Camper (Da Boat)
SAIC Comsystems                 '73 Capri GT 2800 (Da Beast)
San Diego, California           '87 Mustang Lx 5.0 (Da Bruiser?  Soon...)
schwarze@nosc.mil                http://papaya.nosc.mil/~schwarze
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