[Rover] AC/DC Inverter question

[Mike KA5CVH Urich]

From: "Jacob Tennant" <k8jwt@ntelos.net>

> Looking into a power inverter to run my radio system out of my car with.
>
> Radio=10watts RF
> Amp=160watts RF
> Laptop=57watts AC


Mike wrote

A 10 watt <output> radio is going to draw close to 35 - 40 watts <input> a
160 watts <output> will draw close to maybe 500 watts <input> and of course
the laptop @ 57 watts.  That's ~ 600 watts of max load.  Now, inverters are
generally rated on a 13.8 vdc input.  I find that to be pushing the edge of
the inverters capability on an idle <not charging> battery.  I generally
figure useable voltage input to the inverter @ 11.5 volts.

Soooo the Mike swag figure for inverters is arrived at by dividing 13.8 by
11.5 = 1.2.  Multiply your anticipated max load by 1.2 for safe real world
numbers.  In your case a 700 watt load <based on my assumptions about draw>
really needs as a minimum a 700 <600*1.2=720w> watt inverter.  Now,
furthermore, I personally don't want to push an inverter past 80% of its
rated cacity for max draw, regardless of duty cycle, so, to give you a
comfort zone of 15-20%  I would go ahead a swag that up to a minimum 800
watts <720*1.2=864 watts> just to be on the safe side.

YMMV
Mike Urich,   KA5CVH
www.ka5cvh.com
LaPorte TX   EL-29

Amateur Radio *IS* a contact sport!