Date:         Sun, 31 Dec 1995 01:30:58 -0700
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         rickgo@halcyon.com (Rick Gordon)
Subject:      Re: Questions on a 2nd battery

>I'd be interested in the answers to these questions also, please make
>replies public on this topic! Thanks!
>
>Ron Lussier wrote:
>
>>Now that I have the inverter, I want to get a second battery.  I've read
>>most of the archive on this subject, and have a few questions on this
>>oft-covered topic:
>>
>>1)  I understand why I need a deep-cycle battery.  I also know that I want
>>    to stick the battery under the drivers' seat.  The question, then, is
>>    what is the best deep-cycle battery for the job that doesn't 'stick out'
>>    of the battery compartment?  And where would I get it?
>>

I've heard that a 'type 27' battery may fit but I have not found any small
deep cycles other than 6V. You could wire two of those together, in series
I think, to get your necessary 12V. An alternative would be to use one of
the taller deep cycle batteries that are more readily available and put it
under the bench seat in back.

>>2)  A relay isolator sounds preferable to a diode isolator, but I've looked
>>    around and no one seems to carry the switched isolator.  Where would I
>>    find a relay isolator that can be switched off of the ignition?
>>

This is just something aka an X-switch. You apply current to one side and
flips the relay to allow current to flow through the other.
I would trigger it off the alternator wire - that is how VW does it in
their setup. This is the lead coming off the alternator going up to the
dash to drive the little light there. Just splice into that.
To do the actual charging, run the fattest wires you can the shortest
distance possible.

>>3)  Are there any recommendations for shops in the bay area that would do a
>>    good job installing a second battery?
>
>>4)  Assuming that I don't want to run a TV, VCR, or microwave oven, how
>>    large of a battery do I really need?  (Mostly, I want to run a laptop
>>    computer and perhaps an external drive.)

Just calculate using the Amp-Hour of the battery, and the Amps used by your
devices. Remember Watts = Volts x Amps.

-rick

Rick Gordon
Bainbridge Island, WA, USA
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