How long till a 12v electric blanket drains the car battery?

Pick2

Golden Member
Feb 14, 2017
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ball park would be 600 ( if that's amp hours ? Probably not ) / 3 amps = 200 hours :)
Probably a lot less than that.

edit: cca is Cold Cranking Amps - not amp/hours
 

tweakmonkey

Senior member
Mar 11, 2013
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A 35 amp car battery (that's a small size battery) has potentially enough energy to run that blanket for 10 hours. But in reality it would be dead long before those 35 amps are used up. Probably 3-4 hours in the voltage would drop enough to shut it off but the car would probably be unstartable sooner. If it kept going it would permanently damage the battery. A deep cycle battery could probably run it for 7-8 hours I'd guess. But if you do this keep a voltage meter. CCA has nothing to do with capacity. It's only how many amps can be produced at once and this blanket only uses 3 so I don't think your 550 is going to be a problem :)
 
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razel

Platinum Member
May 14, 2002
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By the way, nearly all estimates assume your battery is at 100% charge and 100% health (sulfate free) which only happens when the battery manufacturers rotate stock at your store right when you buy it. It maybe best to cut estimates in half so that you half enough power to start your car.

Though unless you want to chance jump starting your car, I suggest that you buy another battery powered product with a 12v cigarette to run that blanket from. Those battery powered tire compressors/portable jump starter tend to come with plenty of battery juice to keep that blanket warm.
 

jlee

Lifer
Sep 12, 2001
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Keep in mind that for optimal health, a lead acid battery shouldn't be discharged past 50% capacity.
 

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