# Heat Pump vs. old resistive heater



## garsh

Bjørn Nyland compared running camp mode on both a new and old Model 3.
His measurements on the new car were very crude, but it at least gets us in the ballpark.

The new car used 3% of the battery over 3 hours. He assumes a usable battery size of 73.5 kWh, meaning the heat pump used *735 W* in his test.
For his old car, he used 9.4% of the battery. So about 3.1% per hour, or *2.17 kW*

So the resistive heater used about 3 times as much energy in his experiment.


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## garsh

It should be noted that Bjørn had some notion of how much battery degradation his car has, and incorporated that into his calculation.

But the assumption of 73.5 kWh usable energy in the new car might be incorrect. We know that Tesla has recently increased battery pack energy density by 5%. That would make the power drawn by the heat pump more like *760 W*, which is still a vast improvement over the old heater.


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## Needsdecaf

Not surprising. Great upgrade for those in colder climates for sure!


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## Nom

I love how Tesla priorities innovation. ‘That’s a good idea!’ ‘Let’s do it!’ (The quotes I made up for Elon)


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## Feathermerchant

I have a 2018 Model 3 Perf and a new Model Y. The 3 does have Titan 7 18" forged wheels (but not aero) and Michelin Primacy tires. I have driven both round trip DFW-Phila. Temps were upper 30's to lower 40's and in the 3 we were careful with the heat due to the PTC heater but in the Y we were comfortable. The Y has fewer miles on it so more capacity. We would leave an SC showing maybe 10% remaining at the next stop but even driving 5 over or more, we typically arrived with 16% remaining. Never with less remaining than predicted. Really enjoyed the trip in the Y much better.


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## Nom

I tend to think that objectively this is clearly good but not that big of a deal overall .... but .... I find that my mind has thought enough about efficiency that I’m over weighting the significance of this. Found myself thinking through upgrading to a new car ... which is crazy as the $ trade offs are so skewed. Just thought I’d mention ... to me it tells me I need to relax about the efficiency. I’ve been on many road trips with my 2018 M3 and all has gone great.


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## Frédérick St Laurent

Here is another video about comparing heat pump (comparing SR+ 2019 to SR+ 2021) at temperatures around -3°C (26°F):





I know the video is in French (done in Québec, Canada) but I took the time to add English subtitles for non French talking people interested in the results. To make a long story short, on the road heat pump appear to be about 4 time more efficient than resistive heater. Strangely the results we got on our stationary test are different from Bjørn's results. Is it because it was not long enough? Or McHammer (Bjørn's car) has a problem with its temperature sensor as he's claiming in another video?

Anyway, does it worth changing the car "just for that"? I'd say no. But for people living in areas with cold weather, this is seriously increasing the range when you need it the most (when its cold).


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## Feathermerchant

Driving my wife's Y from DFW-Phila-DFW in ~40 degF weather compared to my old Model 3 the energy consumption was near the same but we kept the car a lot more comfortable. On the highway, the heat pump can move heat from the drive unit(s) to the cabin. There's got to be at least 2kW available when traveling at 70-80 mph. But running around town it is probably not that beneficial.


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## garsh

Ingineerix has put out a video on the new heat pump.


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