Another in our irregular series of answering questions from readers, this one from John Q of Eugene, Oregon:
Question: I was wondering how an electric car provides heat and defrosting. Using batteries to generate the heat will drain them pretty fast. Maybe with the 2011 Chevrolet Volt, the internal combustion engine is run for heat? But what about the battery-only 2011 Nissan Leaf?
Answer: In brief, cabin warmth on cold days is provided via resistance heating, which--as you note--uses a lot of current.
However, the Chevy Volt offers heated driver and front passenger seats.And the Cold Climate package offered for the Nissan Leaf includes not only heated front seats but a heated steering wheel as well.
Those items turn out to make occupants FEEL warm enough that the cabin heat may not be necessary, or can be used at lower temperatures. But simply heating seat surfaces and a steering wheel requires much less current than heating volumes of air and blowing them around the cabin.
Under some circumstances, especially if the battery pack has been cold-soaking, the Volt may switch on its engine when started until the pack has warmed up enough to be in the appropriate operating temperature range. Then it will switch off again until the pack is depleted--which is essentially how today's hybrids work.
The Leaf, of course, does not have that option. But when either car is plugged in to recharge, some energy may be diverted to keep the pack at its ideal operating range--either cooling via fans (Leaf) or liquid cooling (Volt), or heating via elements inside the pack.
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Nissan shows a range of 62 miles in stop and go traffic at 15 F outside. Not too bad really. Unfortunately, they don't have a comparable range listed for 68 F temperature and stop and go.
The general information on the web indicates that while heating is significant, range reduction due to heating is perhaps about 15%. Anyone else have any better data?
By Don Posted: 1/21/2011 9:57am PST
By SJC Posted: 1/21/2011 11:04am PST
By danwat1234 Posted: 1/21/2011 11:35am PST
Heater can take over 4,000 watts.
AC takes less than 2,000w.
Does the volt us a Heatpump to heat the cabin or a resistive heater like the Leaf?
Why not consider a reverse-cycle aircon system, much like you may have in your home?.
A retrofit such as this would also eliminate the need for any engine coolant fluid leak complications in the cabin of your car.
Another earlier comment I see, was about Heat Pumps.
These (Peltier Effect) devices consume significant amperage, and in my view are the least efficient electric means for heating the cabin.
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