Date:         Tue, 19 Jun 2007 03:56:23 -0500
Reply-To:     Matt Roberds <mattroberds@COX.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Matt Roberds <mattroberds@COX.NET>
Subject:      Re: Solar panels for your Vanagon..
Comments: cc: Larry Chase <roadguy@ROADHAUS.COM>,
          Frank Condelli <RAlanen@AOL.COM>
In-Reply-To:  <20070618020539.YWWG2131.eastrmmtai105.cox.net@eastrmimpi02.cox.net>
Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed

> From:    Larry Chase <roadguy@ROADHAUS.COM>
> Date:    Sun, 17 Jun 2007 15:06:34 -0700
>
> [Engel MT35]
>
> - Uses 0.7 - 2.5 Amps per hr on 12 volt. I estimate the average usage
>   would be 1.5 amps per hr.
> - Duty cycle, I would estimate approx 50% at 90F outside temps. So
>   figure 12 hrs per day.

A quick Google shows some performance curves at
http://www.thecellarstore.com/Downloads/MT35%20curve_jpg.pdf .  The best
case (given the assumptions there) is 0.5 Ah per hour and the worst case
is 2.5 Ah per hour.

> Of course the cost of each unit is significant ... $145 vs $690.

I wonder how well one of those 2 ft^2 $100 "dorm refrigerators" would
get along with your average $30 12V->120V inverter.  The Energy Star
rating for a couple of these refrigerators implies that they draw
something like 70 watts when running; that'd be about 6 A before
inverter losses.  Also, I know cheap inverters don't like to start
induction motors very well.  The 6 A doesn't compare very well to the
Engel, but it may still end up being less than the Koolatron due to the
duty cycle.  The price is intermediate between the Koolatron and Engel.

> 8) Install a deep cell battery for the cooler.

I agree with using a deep cycle battery.  Car starting batteries really
don't like being cycled below maybe 75% or so state-of-charge.  The
Syncro White Star version is to get a nice AGM deep-cycle battery, but
even a cheap flooded deep-cycle battery will probably cost you less in
the long run.

Matt Roberds