Which uses more battery power, AC or heater/defroster?

Air conditioning takes far more power than the heater. As long as the engine is already warmed up and running, heat is a free byproduct---although using the fan to distribute that heat consumes some power. I believe AC usually comes on automatically with the front defroster, depending on conditions.

 

If you've got the mode set to heat/defog, it may be activating AC, if it behaves similar to the regular prius. This is even if the AC button is not depressed, and it's light off.

I've been monitoring ours with a ScanGauge, sometimes AC runs, intermittently, sometimes not. The lower the ambient temp the less I see AC running. At 5C or lower I don't believe it ever runs.

 

a/c is all electric. heat uses the engine, but will make it run more, so a little more gas. and mendel^^^ is the expert on a/c on even when the button isn't pushed and the light is not lit. in the end, it all comes from the gasoline, so don't worry about it too much.

 

I agree with bisco, the AC probably uses more battery power but running the heat will have more impact on your MPGs overall.

 

electric heat is a huge drain, even the pip doesn't have it. i think leaf and volt do, but most use it judiciously.

 

typically, A/C uses a lot more energy because it doesn't get free heat as with the heater. When defrosting the A/C dehumidifies much better, especially on recirculatiom, the worse as outside temp climbs. Now if its an electric and not hybrid its a toss up and depends on the temperature difference between outsude and inside.

 

Using coolant temperature to heat the cabin isn't "free", it's cheap though. AC, regardless of the method, saps more power, cuts mpg more.

 

Heat can be run for free. Turn temps up, open vents, and turn off HVAC. If you travel 45 mph and higher you will feel warm air coming in. For an added bonus, set direction of air to feet and windshield. If you don't breathe much, carry passengers, or its not raining, this setup will keep the cabin warm and windows clear. This is how I setup in the winter to minimize drain on heat and AC. If the windows do fog, I turn the fan on a few seconds to clear and turn it off again.

 

That would make sense, considering how big of an area the defroster has to heat up, and in the c4 trim, also heating up the side mirrors.

On a related note, I was quite surprised only the 4 trim had heated side mirrors. Heated seats I can understand due to cost, but I can't imagine wiring for the side mirrors would cost that much more to not make it available on the lower trims.

Regarding the fogging in your vehicle, is your air set on recirculate? I only had the fogging problem during winter in my c, and later my liftback, if I had the air on recirculate without the a/c on. If I had it set to have airflow from outside, the fogging issue never came up unless I set the blower really low and jumped in the car right after taking a shower without drying my hair first.

If you need to clear the fog out quickly, open all your windows slightly while driving for about thirty seconds or so. If you don't want too much cold, open a front window and the opposite rear window, such as the driver side front and passenger rear windows instead. This should help clear the moisture out of the air in your cabin faster than blasting the a/c and heat.

 

Mendel - recently saw a picture of the possibly cat or some section of the exhaust from the Prius C - it has two coolant line hookups as if it's using exhaust heat to provide cabin heat. Wouldn't that be completely free? It seems like robbing it from the exhaust would be the smart thing to do.

C

 

both the ac and heat run when you use defrost in the heat mode. It does it on all cars. Its the way it pulls the moisture out of the air. In Air defrost you run only the air, in heat both run

 

There is no reason to differentiate electricity from petrol in a Prius 'c' -- the source energy is always petrol.
This question is one huge ... it depends.

A lot depends on how the systems are used,
and a lot depends on the ambient relative humidity.

'Defrost' mode is an energy sink.

 

The coolant lines at the exhaust are absorbing heat just to heat the coolant, to get the car's engine warmed up faster. That said, it indirectly helps with warming the cabin.

It's all a matter of degree (pun intended), the engine can have excessive heat, and instead of throwing it away via the radiator, using it to heat the cabin is very efficient.

OTOH, the Prius spends a fair bit of time in EV only, especially at lower speeds. Then taking heat from the coolant to heat the cabin will have some impact. Again, not as bad as AC, in my experience.

I've got a constant ScanGauge monitoring engine temp. The typical coolant peak temp, rarely seen, is around 90C. In around-town driving, it's more common to see the temp around 60~85C.

 

Upstate ny here -6 again today. IMO using the heat takes much more mpg away than the ac. This month I'm down to 38 mpg and the heater in the prius I only fair, it must run almost constant to keep the cabin warm, which means the engine is on most of the time


If I use Eco mode mpg goes back up but heat isn't acceptable at these temps

In the summer months using the a/c my mpg is always in the low 50s
So I'm thinking heat is costing me more than a/c

 

agreed. you're basically driving a gasser at those temps. albeit a frugal one.

 

A gasoline-powered heater would be the logical answer; Volkswagen has used them safely for years, but it would cause instant hysteria among the risk-averse types who seem to have invaded our society.