"Marco Leon" wrote

I have a common problem of possessing a Tanis heater in my Warrior but
no electrical source by which to run it. Past newsgroup and online
knowledge (including an email from Tanis) say that at least a couple
of hours are needed to heat the engine in about 20 deg F temps.

An old post from 1999 suggested that a "deep cycle" battery be used in
conjuction with an inverter to be turned on a couple of hours prior to
flight.

Does anyone currently use this setup? If so, any suggestions on the
myriad of battery types and brands?

More information is needed, as to the current draw of the units when plugged
into a standard outlet. Buy or borrow an AC amp meter, and report back.
Also, do you have the cabin heater, or just the engine heater?

I have used power inverters for quite a few different things. They are good
at some uses, and very poor at others. Part of the design that causes some
problems is the wave form in most consumer inverters. If it is called a
modified sine wave converter, it is basically a square wave, with on and off
pulses, and not much in-between, unlike a sine wave.

They are very poor at running inductive motors, like air conditioners and
refrigerators. Sometimes it is necessary to run something like a light bulb
along with the refrigerator, to trigger the unit into producing the wave
form.

As I recall, most inverters say right on them that they are not to be used
for powering resistance heaters. They will do it, but it will strain the
power switching transistors. That seems to be the weak link. Also,
chargers for power tools and such that are constant current, variable
voltage units should not be used on inverters. I burned out a Dewalt
charger on an inverter, while trying to do what was not recommended.

Inverters usually have a rated wattage, such as 500 watts constant, 1000
watts peak. The peak is a joke. It may do that for a millisecond, but any
more will result in a very low output voltage, and trigger a reset
condition, which usually must be done manually. Not a good thing, if you
are not there.

I would think that if you do go this route, you would be advised to get one
at least twice as big, or more. If you say the heater unit draws 500 watts,
get a minimum of a 1000 watt, but a 1500 watt or 2000 watt would be better.

Post some more specifics, if you will. My feeling is that it will be
doable, but not cheap. Triggering a small electric start generator may be a
better option.
--
Jim in NC