Cabin Heating, excessive battery usage

Cabin Heating, excessive battery usage

I charged my car last night. It was 47 degrees outside. I had 248 miles range. I drove a total of 41 miles and consumed 71 miles of battery. That is about 40% battery for just cabin heating. I had a Nissan Leaf before. Heating the cabin consumed 25% on average. The Model 3 usage seems high to me. Does anybody have the same usage or is my usage very high?

Bighorn | 27 oktober 2018

Not enough info.

jordanrichard | 27 oktober 2018

So in your Leaf you had a sperate meter to measure the energy consumption of just the heat.........?

rfindley | 27 oktober 2018

The leaf was just a guesstomate. Over time you could tell the driving distance decrease in winter. What additional information do you need? Asking a straight foward question. Is this normal or close to normal. My thinking at 40% a 310 mile battery will give only 190 or less, effective driving range.

jordanrichard | 27 oktober 2018

Well, I have never seen such a hit to range with temperatures in the 40’s. I have gone through 4 winters with my Model S, and the highest I have seen was 30% hit, but that was when temps got down into the single digits. Still wasn’t an issue though since my car has such a large range to begin with. Your car has a much larger range than my S85 (265 miles when new), so it should be even less of an issue.

Bighorn | 27 oktober 2018

You are making an assumption about your baseline efficiency matching the EPA standard. You can't assume that 40% is heat and I've never seen that shy of sub-zero temperatures before the car warmed up. The heater draws 4.3kW max supposedly, so do the math.

BostonPilot | 27 oktober 2018

I've had EVs in the past, so I knew I was going to take a hit when I had to start running some cabin heat...

I was on a drive recently where I would have expected to be running about 275 Wh/M and was instead pulling 300-320... I was pretty sure it was the cabin heat - outside temp was about 45 and I think I had the cabin set to 60. I couldn't turn on recirculation because it was humid enough that when I would do that, the windows would fog over in a few minutes. Luckily with the big battery there was no problem of not having enough range.

One thing I would like to see is an addition of a "heat on/off" in the climate controls that works like the "AC" control, i.e. that I could force the car not to use the cabin heater, without having to adjust the cabin temperature to "LOW". That way I could keep the fan running to keep fresh air coming in to control window fogging, without having to adjust the temperature up and down.

On one of my other electric cars there was a display which discriminated between electricity being used to move the vehicle, vs other stuff like AC/heat. I'd love it if something like that was available in the energy consumption display. Maybe two separate lines on the graph - one for the propulsion, and another for all the ancillary devices.

SalisburySam | 27 oktober 2018

@jordanrichard, yes my 2012 LEAF has display gauges for 3 items: traction battery, HVAC, and all other. The displays are in kw to show live consumption rates. Pretty handy actually.

@rfindley, +1. Recent trip of 120 miles to/from an airport using heated seats and cabin heater (and wishing there was a steering wheel heater like the LEAF has). Started trip at 80% (248 miles), and ended at 25% (78 miles), so 55% of battery (170 miles) to go 120 miles. All this at 65mph mostly interstate highway.

Now the kicker: it was pouring rain, biblical rain, ark-constructing rain the entire trip. I know that rain adversely affects mileage, and I’m sure part of my losses were rain. But wow, for trips with heat and/or in bad weather, plan on more Supercharger stops for sure.

mazers | 29 oktober 2018

@BostonPilot, I wish that there was a 'vent' button, that neither heated nor cooled the incoming air. It would just allow fresh air to come into the cabin. Really old school, I guess.

Bighorn | 29 oktober 2018

In Wyoming, we call those windows:)

Magic 8 Ball | 29 oktober 2018

Coffee spit
Clean up in the computer department please.

mazers | 29 oktober 2018

@Bighorn, LOL, nice but I don't want the noise.

Pepperidge | 29 oktober 2018

Leaf uses heat pump for heating and it is around x2 ~ x3 efficient than Tesla's resistive heater.

spuzzz123 | 29 oktober 2018

Makers agreed windnoise is annoying with windows cracked. Couldn’t you manually set the fan with recirculating off and fine tune your temp to what you want?

spuzzz123 | 29 oktober 2018


gballant4570 | 29 oktober 2018

Sam, I haven't had my 3 all that long, but I believe that I am beginning to discover that rain and standing water in the road hit your battery harder than cabin heat, or at least as hard. But I only have one rainy day's driving to base that on.

My wh/m average was 234 going into that day, and that day's wh/m ended closer to 290. There was also some cabin heat/defrost usage involved, but not heavy. Temps were in the 40s. That was a ~19% efficiency loss based on wh/m. Since I've only had the car about 3 weeks, my lifetime wh/m went to 236....... I had also driven several days with some seat heaters and some cabin heat, with a smaller impact on efficiency - I don't recall the numbers, but I believe it was closer to 5%.

hokiegir1 | 29 oktober 2018

@Spuzz -- unfortunately, not if the external temp is below 60*F. That's as low as the settings on the HVAC go. I'm in the "fan only -- no temp adjustment" desired camp as well. Once the outside temps are in the 50s, it would be nice to be able to pull in some air without heating it to 60*.

And yeah -- not a fan of window noise in general. That's more airflow than I like, as well.

gballant4570 | 29 oktober 2018

Sorry for hijacking.... but this calls for a story....

Many years ago, I was going to town with my great uncle. It was February, in Iowa. We rode in his old pickup. I don't recall the color, it was just rust. I had to get snow out of the seat before I sat down, as did he. As we got moving, I tried to roll the window up. The crank was stuck fast.
So I mentioned, "Uncle Walter, your window won't go up."
His response? "It won't? Well, let's see...I rolled that window down the day I got this truck, and I guess I ain't rolled it up since."

Times change......

billtphotoman | 29 oktober 2018

1) If your 41 total miles were several shorter trips this isn't surprising since it uses a lot of energy to initially warm the cabin.
2) If where your car was left was at or near the 47 degrees 1) becomes exacerbated.
3) At higher speeds the cold dense air makes a big difference too,

mpratola | 29 oktober 2018

Rain seems to have a large effect on range, heat not so much (so far). I think an "intermittent" heat setting would be good as I find I can turn the heater on and it rapidly warms things up within a few minutes and then I can turn it off for awhile before I feel the need to turn it on again. Something that automated this (and depended on outdoor temp) would increase efficiency and keep things defogged without pumping in cold outdoor air.

Bighorn | 29 oktober 2018

Rain and heat can both have outsized impacts.

Murduc | 29 oktober 2018

@Pepperidge, do you have some references for that? Not that I don’t believe you, but a Leaf being 3x more efficient at anything seems unlikely. Lol.
I have a Leaf and the cabin heat is such a drain I disabled it with a popular mod. Not only is it wasteful keeping a tank of water hot outside the cabin, in the cold elements, at speed, but the darn thing is doing it even when you do not want or need it. Happily an intrepid Leaf owner makes a plug and play wiring harness bypass with a switch that allows you to fool the car into thinking the water is already hot.

syclone | 29 oktober 2018

It’s funny that this topic came up today. I’ve been driving my LR-RWD M3 without paying much attention to the A/C system. I drove about 100 miles today with the ambient temp. ~55 degrees. The system was set to 72 degrees. I could tell that the heater was running most of the time. For the first 50 miles or so, The energy usage at ~70 MPH was 330 – 340. Then I just turn off the system – no heat, no AC. The energy usage started to gradually drop until it hit 240, which is the “sweet spot” At that point, I got into the HOV lane and raised my speed to 78. The energy usage started to rise again until at the end of the trip energy usage had risen to 252.
The heating system seems to really hit the cars efficiency really hard.

Bighorn | 29 oktober 2018

"The heating system seems to really hit the cars efficiency really hard."

Correct--which is why I countered mpratola's suggestion to the contrary. Early measurements show 4.3kW for the heater, which adds up and certainly bumps the Whs/m.

beachmiles | 19 oktober 2019

Yet another forum where additional HVAC settings would be useful.
We need 2 temp setpoints of where you want the heater or AC to come on, otherwise just use the vent. Just like how the nest works.
1 being the low setpoint where the heater comes on
1 being the high setpoint where the AC comes on.

In my case I would set the low at 58F and the high at 72F. That's a 14 degree range where I won't waste any power on heating or cooling the cabin.

Having 1 temp setpoint like we have currently forces people to waste power when they really don't need the cabin heated or cooled. Yes auto works, and if I had home or workplace charging, or solar I prob wouldn't care as much... But if I'm doing a road trip somewhere I want to maximise my range and would rather not have to fiddle with the AC settings all the time. Not to mention wasting energy is wasting energy, would rather not do it regardless.
This thread has a good name which summarises my frustration.