How much fuel Prius C uses if AC is running overnight (8 hours)

depends on the delta between the climate setting and ambient air. probably a gallon on average.
many use their prius for camping, living and back up generators. it won't harm the car at all. it was designed to sit in traffic in hot weather for hours on end.

 

What bisco said ... the variable speed compressor can draw anywhere from under 250 watts to over 2000, if I remember right from watching it on a ScanGauge ... under lighter loads it can draw even less than 200 on average, by cycling on and off.

Add to that a few hundred watts for the rest of the car's electrical system. You should be able to find conversion figures somewhere for watt-hours in a typical gallon of gas. Don't forget to throw in an efficiency factor maybe around 0.3 or so. Should get you close-ish.

-Chap

 

Not sure how to use this chat.
Just purchased a 2014 Prius. Not thrilled with the miles per gallon.
What setting should I keep it on?

 

congrats and welcome!
keep it in eco, fill the tank, reset a trip meter, and report your calculated mpg next time you fill up.

in the meantime, you have a used car. many things could potentially be causing a problem.
oil level, air or cabin filter, tyres pressure, 12v battery, throttle body and maf, egr and intake manifold, the list goes on.
how many miles on her?

p/s; go to the main forum page, click on gen3 maintenance and troubleshooting forum, click on 'start a new thread' at the top right of the threads, and post your problem with as many details as possible.

all the best!

 

I experienced just this situation... only not while camping... and in possibly the worst case scenario.

I was stuck in Kentucky, overnight, while traffic stopped on the highway. 8 hours in park on I-75 in negative temperatures. I kept both seat heaters on and the internal temperature at 80 degrees for the entire time while my wife and I had to watch as other drivers were turning their cars off to save gas.

In this scenario, I used a total of 2 blips on the fuel bar. So it was probably less than that since we had already been driving.

35.77 mpg on that tank.

 

I just tested this with hybrid assistant and the results were surprising.

 

Thanks for that, you're sort of adding the warm-weather counterpart to my cold-weather "on hunkering" threads.

A few things I would add:

• Cycling on and off is not the only trick up the compressor's sleeve. It is also variable-speed, and when I say variable, I mean really variable. The power consumption figure for the compressor when it's running isn't just one number, it can be anywhere from around 0.2 kW to 2.5 kW or more. (Generally, if it is cycling on and off; it is going to run at the lower end of that range when it runs; if the average demand were higher, it would be able to just run steadily at the corresponding speed, and not cycle.)
• Humidity matters, more than you might think. An air conditioner does two main things: (1) reduces the temperature of air, and (2) extracts water from it (which drains out a tube through the floor). Both take energy*. So people replicating this test in different places with the same indicated temperature could still see quite different results if the humidity were very different.
• You have a lot of options besides using the car to keep the whole cabin at your favored temperature. In my "on hunkering" threads, I included strategies like using the car's heat very, very little (essentially keep the cabin non-freezing) and curling up between the heated seat and a 40 watt heated blanket. That's quite comfortable, and very efficient.
  • You've got similar options for cooling. Even at home, I generally keep my thermostat set for 29 ℃ (about 84 ℉) overnight, with a ceiling fan lazily turning over the bed. Without the fan it'd be stifling, but with the fan it's quite nice. The A/C still keeps the humidity low enough for that to work.
  • Even a tiny little cheap car accessory fan can make a big difference to comfort in the Prius, if you bring it into the back where you're sleeping, as the car's blower and the vents in your dash just don't create a lot of air motion back there.
  • For more demanding conditions, there are things on the market that are like mattress pads with tubes in them, and a head unit that pumps either heated or chilled water through them. AquaBed and chiliPad are a couple of names. The ones that include a thermoelectric cooler as well as heat for the water are more expensive. I haven't done any experiments with them, but I might consider getting a cheap one, without the cooler, insert some looped-up aluminum tubing in the water circuit, and stick that in front of one of the car's A/C vents. I suspect that would be plenty.
• @lech auto air conditionin has documented how not making sure the A/C system is properly charged can increase power consumption by a boatload (I was going to say 'a ton', but that's a real unit in A/C work, so ....)

* before somebody picks on me to say the condensing water gives up energy: yeah, it does, but in the wrong place, and the A/C still has to move that energy outside the cabin.

 

Years ago, I had one of these in a van conversion: https://www.amazon.com/Electrowarmth-Mattress heater. It worked real well, nowadays with the Prius, I wonder what the thermal and KWH advantages of it would be versus keeping the entire car warm? Only a little over a 6 amp draw, and it cycles on and off I believe. I remember turning it on an hour or so before stopping for the night, during a Canadian winter, and the bed was cozy warm to get into.