Date:         Thu, 18 May 2000 18:50:03 -0400
Reply-To:     David Beierl <dbeierl@IBM.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Beierl <dbeierl@IBM.NET>
Subject:      Re: Heat in an air-cooled Syncro (long, boring, self-involved)
Comments: To: "T.J. Sheffield" <kl7ts@HOTMAIL.COM>
In-Reply-To:  <20000518203708.87072.qmail@hotmail.com>
Content-Type: text/plain; charset="us-ascii"; format=flowed

At 16:37 5/18/2000, T.J. Sheffield wrote:
>dash to provide defrost and some cabin heat.  The nichrome heating element
>wouldn't care if it was fed 220v or 408v, either AC or DC, and the current
>carried by the system would be reduced based on the higher voltages.

Depending on what you mean by "doesn't care" -- a given element will draw
more current as you increase the voltage, and the power increase will be
the product of voltage and current.  Assuming that the element resistance
remained the same (which it won't; it increases as the element gets hotter)
doubling the voltage will double the current and quadruple the power.

Also, depending on the construction of the element, you will have
significantly higher impedance on AC than DC, most particularly if you're
using a 400 Hz AC generator such as you would find on aircraft.  You can,
for example, buy coffeepots designed to run on 110 VAC or 12 VDC.

Then there's the little matter of voltage regulation, unless maybe you're
shifting over to a constant-engine-speed gasoline-electric drive <g>.

As to running a 400-volt power circuit in a Vanagon -- I wouldn't, myself.

Sorry to be such a wet blanket...
david
David Beierl - Providence, RI
  http://pws.prserv.net/synergy/Vanagon/
'84 Westy "Dutiful Passage"
'85 GL "Poor Relation"