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 | 2018年10月27日

Not enough info.

jordanrichard | 2018年10月27日

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

rfindley | 2018年10月27日

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 | 2018年10月27日

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 | 2018年10月27日

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 | 2018年10月27日

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 | 2018年10月27日

@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 | 2018年10月29日

@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 | 2018年10月29日

In Wyoming, we call those windows:)

Magic 8 Ball | 2018年10月29日

Coffee spit
Clean up in the computer department please.

mazers | 2018年10月29日

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

Pepperidge | 2018年10月29日

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

spuzzz123 | 2018年10月29日

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 | 2018年10月29日


gballant4570 | 2018年10月29日

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 | 2018年10月29日

@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 | 2018年10月29日

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 | 2018年10月29日

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 | 2018年10月29日

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 | 2018年10月29日

Rain and heat can both have outsized impacts.

Murduc | 2018年10月29日

@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 | 2018年10月29日

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 | 2018年10月29日

"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.