For Christmas, my wife gave me an automotive electric blanket that uses the 12 volt power plug. Not sure yet what the wattage on this is but was really wondering if the 12 volt plugs take the power right off the small battery? I am assuming the 110 outlet comes off the big batteries but never really thought about the 12 volt plug beside it. Thinking about how long I can run the electric blanket without having to run the engine to recharge. I'll just put the ignition on accessory.

For those wondering why, here is what is behind the elec blanket. I work a sh*tload of hours at my job and many times I have a couple hours between the OT shift and the regular day shift - plenty of time for a quick nap. I won't sleep in a running car since it wastes gas and carbon monoxide scares me. Since it gets ****ed cold here at night in the winter my wife got me the elec blanket so I don't freeze to death.

On a related question, has anyone tested the 150 watt limit on the 110 volt outlet? I am tempted to test that by seeing how many lightbulbs I can run on it - 150 watt seems so wimpy.....

I believe all the electric accessories use the 12V battery just like a normal vehicle. The 110V outlet is just a small inverter, which is why it has a 150W limit - this is fine for laptops and phone chargers, even a TV, but won't power high-drain things like hair dryers or vacuum cleaners.

I don't know how much juice that blanket will draw, but I don't think you'll even have to put the ignition on accessory because the 12V plug next to the 110V is constant power (the other one on the right side of the dash console is switched power though).

This brings up another question... what happens if we drain the 12V battery? Doesn't the ICE start up using the HV battery?

The ICE does start with the HV battery but you need enough juice in the 12V battery to energize the relay which isolates the HV battery when the ignition is off. I left a laptop running in mine and drained the 12V battery a while back and it completely kills the vehicle. You have to jump the 12V battery to start after that. I have a portable jump starter and just plugging that into the cig lighter plug was enough to energize the relay and start it right up after that.

My 4WD
Wife's 4WD

The 110V is inverted from the 12 volt battery? I always assumed it came off the 330 volts that was in the back. So all those amp-hours sitting back there and that plug runs off the little battery - seems a little bass-ackward.

I think both 12 volt plugs on the '05 are switched (as is the 110). I'll have to check on that.

Nope - on mine ('05, purchased in April), one is switched and the other is constant.

That's the answer right there. Buy yourself a portable booster. Then, run the blanket without worry. If the 12V ever discharges beyond starting capability, you've got the portable booster!

<Best Tank Economy!><Best Tank Endurance!>

It is not healthy for any battery used in automobiles to be run down to empty. The danger lies in un-equal cell capacity. As you continue to discharge the battery the cells which are in series continue to put out the required current however the weaker cell continues to have the current pass thru it which in essence puts a reverse charge on it destroying it. Be careful. Also any on board electronics that requires a keep alive voltage will be re-set. I remember something in the manual for my FEH about the engine and transmission control unit need to be re-trained if the 12 volt battery is disconnected.

If you are concerned about draining your battery why don't you get one of those jumpstart gadgets( just a sealed rechargable lead type battery) that has jumper cables and a 12 outlet.Just charge it every day or so.It will run a blanket like that for a few hours.I've run a 60 watt TV for a couple of hours with one so the battery is at least 120 watt-hrs. If your electric blanket is 3 amps about 36 watts (3a x12v) , it will be good for 3-4 hours.Luck,Charlie
PS besides the Prius is a bit prone to discharging the small battery,so it would be a good idea to have one around to jump start it(you can get them with airpumps on them also-tires etc)

can't you just turn the car on? i mean ya the engine will run but not all the time, it will turn off when its warm enough, and then on again when not. By then you don't need to worry about anything! just turn the temperuture setting to cold and use ur blanket.

i got around 20 km a liter when i drove a civic 5 spd using advanced hypermiler techniques
and now I drive a salvage nwh20 prius that gets almost to 25 km/l with 192,000 km to date.

The problem with that is that when it is cold enough outside to need the blanket, it is cold enough outside so that the ICE would run most of the time. It runs in order to keep the batteries charged as well as to keep the engine, Cat converter, etc. at normal operating temperature for emissions reasons. Besides, there would still be the issue of carbon monoxide and the engine starting and stopping would get annoying.

I am thinking I will just try to calculate how long this thing could run to see how long it can run based on the battery rating and some wildly generous assumptions. Then I'll just test my theory. Worse thing that happens is I have a dead battery. I have Triple A....

The ironic thing is my nights may be going away soon anyway. Potential promotion in the works that would be a big pay cut (no overtime) but I would get a company vehicle and be home every night.