"Marco Leon" wrote in message
ups.com...
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.

Looks like the smallest Tanis heaters are around 250 watts. Even with a
good inverter you will probably consume around 300 watts, or 25 amps at 12
volts.

Most of the deep cycle batteries are rated based on a 20-hr discharge rate.
That means that a 225 amp-hr battery will only deliver that storage capacity
when it is discharged at the 20-hr rate, or in this case about 12.5 amps -
if you discharge it faster (25 amps) then you will not get rated capacity.
Of course, the battery will not do as well in very cold temperatures either.
In addition and IIRC, deep cycle batteries are designed to be discharged to
about 20% of capacity and no more.

Even so, it looks like getting a couple of hours out of a 225 amp-hr battery
shouldn't be a problem. You will just have to haul the thing around and
keep it charged all the time to be able to use it and to keep it healthy. I
wouldn't expect that you'd be able to run more than about 5 or 6 hours
continuous though, and again, that's on a healthy battery.

If your heater has a higher rating than 250 watts, you would have to take
that into account and decrease the numbers above accordingly.

BDS