Neil was asking an Ohm's Law questions about calculating appliance
current draw.

Herewith, formerly on the old wiki, then lost, and now placed back on
the wiki for all to use, is the handy Battery Demand Calculator:

<http://www.vanagonwiki.net/wiki/Living_Off_The_Grid_Articles>

Written for the fine folks in the VW Vanagon Westfalia community,
but useful wherever fine living from lead-acid batteries is found.

--
Rocky J Squirrel

neil n wrote:
> Hi all.
>
> Viewing this:  http://tinyurl.com/23utmeo in the store, I wondered how
> many amps it would use. On the back it says: 12 Watts, 12 Volts. Only
> vaguely recalled Ohm's Law at that moment, didn't obviously know the
> resistance of the unit, so couldn't calculate amps used. Bought it
> anyway.
>
> At home checked current draw. Low -  0.45 amps. High - 0.6x amps
>
> But entering 12 volts and 12 watts here,
> http://www.the12volt.com/ohm/page2.asp shows 1 Amp. Here:
> http://www.csgnetwork.com/ohmslaw2.html  0.58 amps. They both *appear*
> to use the same formula though the latter gives closer to what I
> measured on high speed, hence the makers rating I assume.
>
> What am I missing or doing wrong? Or more to the point, what formula
> should I memorize?
>
> Looks were deceiving. Had it been over 1 amp draw, I likely wouldn't
> have purchased it thus saving time. As it turns out, for my needs,
> 0.45 amps/hour over a few nights use, shouldn't draw down my group 42
> aux. battery too far.
>
> Thanks!
>
> Neil.
>
>
> --
> Neil Nicholson '81 VanaJetta 2.0 "Jaco"
>
> http://tubaneil.googlepages.com/
>
> http://groups.google.com/group/vanagons-with-vw-inline-4-cylinder-gas-engines