Originally Posted by Milous
3+ to 5 range depending on engine size (400w-600w).
That's good info. Assuming an inverter is 90% efficient, 600w produced would require 667w consumed from the vehicles battery. That's 55 amps. Most car batteries are 75 to 100 amp hour rated. So, in the hour or so it would take to raise the oil temperature significantly, the battery would be seriously depleted to the point it probably won't crank the cold engine! Remember, batteries are already heavily burdened in cold weather and although the oil in the pan is warm, the rest of the block is still cold.
So don't try using an inverter to power your block heater...unless you use a spare battery. A small generator would work although probably not practical. If you KNOW you are going camping in the Alaskan winter, a generator would be handy.
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