Quote:
Originally Posted by MetroMPG
Unfortunately, they don't quantify how much electricity they used, so it can't directly answer your question.
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I did find some useful information on the DEFA web site tho, in their technical manual it states:
Quote:
At 0°C/32°F, the DEFA WarmUp time-program controller switches
on 90 minutes before the departure time. During this period,
the engine temperature is raised by approximately 30°C/85°F
(when a 600W engine heater is used).
At -17°C/2°F or lower, DEFA WarmUp switches on 196 minutes
before the departure time and the engine temperature is
raised by approximately 50°C/90°F (when a 600W engine heater
is used).
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so 1,900 watt hours to give a temperature rise where benefit is seen, this is a European company so I think it's safe to assume that it's a modest sized 4 cylinder engine, so a larger car or truck engine is of course going to take more energy and there tests were plugging in for 3 hours when it was -20°C/-4°F.
Sure seems like a better idea then letting it idle or driving with an ice scraper in one hand.