Date:         Thu, 18 Jan 2001 15:37:42 -0500
Reply-To:     David Beierl <dbeierl@ATTGLOBAL.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Beierl <dbeierl@ATTGLOBAL.NET>
Subject:      Re: AC powered Air Cond.for van
Content-Type: text/plain; charset="us-ascii"; format=flowed

At 02:08 PM 1/18/2001, phil stanhope wrote:
>Can I run a DC to AC converter to the wall A/C and have it on while
>i drive?

Yes, at least in theory.  I have my doubts that a 5000 BTU/hr unit would
cool adequately (or maybe even noticeably) while you're driving.  I think
the automotive units tend to run up above 10,000 BTU/hr and I have a notion
(could easily be wrong) that the Vanagon unit is around 16,000
BTU/hr.  Also the automotive units move a great deal more air than a window
unit.

>Do I Need a bigger alternator?

Quite likely.  But first you have to settle on the size of your A/C and
then find an inverter that will not only run it but also start it.  I don't
know A/C starting loads except that they're much higher than running
loads.  Inverter mfrs may be helpful here.  In general, you'll need about
ten amps of DC current for every amp of AC, so a machine that draws 7.5
amps at 110vac (typical modern 5000BTU unit is probably rated a bit less --
at least on the nameplate) is going to need around 75 amps of 12vdc, which
is not all that much less than nominal starting current for a smallish
engine like the Vanagon has.  Be aware that the nameplate ratings for A/C
units are for running under specific conditions that give a favorable
number -- actual current draw can be significantly higher (in...er...hot
weather, for example).

Once you have that end of it sorted out you'll be in a position to know how
big an alternator you might need, and how much battery capacity, and
whether the alternator can be driven with one belt or will need two etc. etc.

Could be an interesting project, but I certainly wouldn't rush into it
carelessly.

david

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