EVs with different types of heaters?

D

dogememe

Joined
Apr 15, 2017
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Location
California
On my Volt, AC is fairly efficient, but the heater tanks my range/efficiency. It uses 3-6Kw constantly to the extent that if I'm going to use the heater I may as well run the gas engine because at my electricity prices it's cheaper to put gas in than "waste" the battery power for the heater. Luckily I rarely have to use the heater and if I do it's on my way to work where I can sometimes charge my car for free.

Anyway, it is my understanding that Teslas and some other EVs use a "heat pump" system instead of what my Volt uses which is basically a huge resistor.

Can someone explain to me how this heat pump thing works? And do Ultium EVs (such as the upcoming Equinox EV) use the more efficient heat pump or the old-school resistive heating? And how much power does that use?
 
dogememe said:
On my Volt, AC is fairly efficient, but the heater tanks my range/efficiency. It uses 3-6Kw constantly to the extent that if I'm going to use the heater I may as well run the gas engine because at my electricity prices it's cheaper to put gas in than "waste" the battery power for the heater. Luckily I rarely have to use the heater and if I do it's on my way to work where I can sometimes charge my car for free.

Anyway, it is my understanding that Teslas and some other EVs use a "heat pump" system instead of what my Volt uses which is basically a huge resistor.

Can someone explain to me how this heat pump thing works? And do Ultium EVs (such as the upcoming Equinox EV) use the more efficient heat pump or the old-school resistive heating? And how much power does that use?
Click to expand...
Heat pump is an air conditioner which operates in both directions. An AC only moves heat in one direction (ex house/car to the outdoors). Heat pumps are very efficient except when it gets really cold outside because there's less heat that the system can pull out of the comparatively colder air. To counter the reduced cold weather performance EV's take heat generated by the battery and driveline.

Heat pump will use about 15% less energy vs resistance heat.
 
dogememe said:
On my Volt, AC is fairly efficient, but the heater tanks my range/efficiency. It uses 3-6Kw constantly to the extent that if I'm going to use the heater I may as well run the gas engine because at my electricity prices it's cheaper to put gas in than "waste" the battery power for the heater. Luckily I rarely have to use the heater and if I do it's on my way to work where I can sometimes charge my car for free.

Anyway, it is my understanding that Teslas and some other EVs use a "heat pump" system instead of what my Volt uses which is basically a huge resistor.

Can someone explain to me how this heat pump thing works? And do Ultium EVs (such as the upcoming Equinox EV) use the more efficient heat pump or the old-school resistive heating? And how much power does that use?
Click to expand...
the nice thing about the Volt is you can have unlimited cheap heat... just run the engine!
 
BMWTurboDzl said:
Heat pump is an air conditioner which operates in both directions. An AC only moves heat in one direction (ex house/car to the outdoors). Heat pumps are very efficient except when it gets really cold outside because there's less heat that the system can pull out of the comparatively colder air. To counter the reduced cold weather performance EV's take heat generated by the battery and driveline.

Heat pump will use about 15% less energy vs resistance heat.
Click to expand...
I have worked in the energy industry building heat pump systems years ago. In general a heat pump can be at least twice as efficient as resistive Heating, and often more than that on efficiency. So you can expect a heat pump system to use less than half the amount of power that a resist a heating system would use.
 
JimPghPA said:
I have worked in the energy industry building heat pump systems years ago. In general a heat pump can be at least twice as efficient as resistive Heating, and often more than that on efficiency. So you can expect a heat pump system to use less than half the amount of power that a resist a heating system would use.
Click to expand...
Ya I was thinking within the context of power consumption of an EV in winter. Tesla says resistance heat accounts for 20 percent of the power consumption whereas the HP is around 8 percent.
 
dogememe said:
On my Volt, AC is fairly efficient, but the heater tanks my range/efficiency. It uses 3-6Kw constantly to the extent that if I'm going to use the heater I may as well run the gas engine because at my electricity prices it's cheaper to put gas in than "waste" the battery power for the heater. Luckily I rarely have to use the heater and if I do it's on my way to work where I can sometimes charge my car for free.

Anyway, it is my understanding that Teslas and some other EVs use a "heat pump" system instead of what my Volt uses which is basically a huge resistor.

Can someone explain to me how this heat pump thing works? And do Ultium EVs (such as the upcoming Equinox EV) use the more efficient heat pump or the old-school resistive heating? And how much power does that use?
Click to expand...

Heat pumps have a range of efficiency that varies from no better than resistive heat to some multiple of efficiency The HVAC industry refers to this efficiency as a COP number, or Coefficient of performance.

Part to the reason for this wide range is that in some cases they run resistive heating to keep them from freezing. A heat pump running in this mode is the same or worse.
 
dogememe said:
And do Ultium EVs (such as the upcoming Equinox EV) use the more efficient heat pump or the old-school resistive heating? And how much power does that use?
Click to expand...

Yes, GM's Ultium family has a heat pump. "Ultium Energy Recovery" is what they're calling the concept; It's how the marketing department describes a heat pump.

https://www.caranddriver.com/news/a39868282/gm-ultium-energy-recovery/

https://insideevs.com/news/581884/general-motors-ultium-energy-recovery-system-revealed/
 
To keep warm on those cold winter mornings, I follows Ford's advice and use the seat heater and steering wheel heater. It works out just fine. We do get freezing temps here in Kingman.
 
MrHorspwer said:
Yes, GM's Ultium family has a heat pump. "Ultium Energy Recovery" is what they're calling the concept; It's how the marketing department describes a heat pump.

https://www.caranddriver.com/news/a39868282/gm-ultium-energy-recovery/

https://insideevs.com/news/581884/general-motors-ultium-energy-recovery-system-revealed/
Click to expand...

Ultium product has a heat pump but how well it implemented is a valid question.

Based on the lyriq forum, Ultium appears to have a problem proportioning its heating and cooling between the battery and the cabin.

Hyundai and several other EV makers also have this problem which most often appears during DC fast charging in hot or cold weather where the battery charging and the cabin HVAC become compromised.

Telsa solved this problem, with their octovalve/ heat pump combo.
 
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Rand said:
50-70% less except in extreme cold.
Different application but my water heater is between 66% to 75% less vs resistance heat.
Click to expand...
I was speaking in terms of the difference in total power consumption in an BEV. Your numbers are about the same as mine just expressed differently.
 
BMWTurboDzl said:
I was speaking in terms of the difference in total power consumption in an BEV. Your numbers are about the same as mine just expressed differently.
Click to expand...
Seems like you thought that but didnt get it onto paper fully?. :unsure:

BMWTurboDzl said:
Heat pump will use about 15% less energy vs resistance heat.
Click to expand...
I do see where you were going with it after farther explanation.
but even that needs a giant asterisk
if you arent using the heat there is no penalty for not having the heat pump.

And I'd imagine the heat isnt used much in CA vs MN etc.
Also if you are sitting somewhere stationary the heat pump again would use 50% less energy..
so trying to simplify the usage to "heat pump uses 15% less power than resistance" is oversimplified and while average applies to no specific circumstance.

My point would be saying the heat pump uses at most 50% compared to resistance is enough and truly shows the importance of that feature.
 
In 20f weather my ev6 gt uses a bit over 2kw for hvac, and maintains the cabin well. My range on my typicsl commute goes from 3.4mi/kwh in the 70f range, to 2.5mi/kwh.
 
BMWTurboDzl said:
Ya I was thinking within the context of power consumption of an EV in winter. Tesla says resistance heat accounts for 20 percent of the power consumption whereas the HP is around 8 percent.
Click to expand...
Using those figures suggests a 60% reduction in power use for heating and implies a 2.5 COP. This seems to be realistic if not outright conservative assuming that they have employed a variable speed Copeland scroll compressor. FWIIW my stationary heat pump is rated at 3.46 COP at 47 degrees F and 1.96 COP at 17 degrees F.
 
2005jettatdi said:
To keep warm on those cold winter mornings, I follows Ford's advice and use the seat heater and steering wheel heater. It works out just fine. We do get freezing temps here in Kingman.
Click to expand...
I have a coworker with multiple EVS and we're in a cold climate. Apparently that works quite well to warm up a person instead of warming up the entire cabin.
 
2heeldrive said:
the nice thing about the Volt is you can have unlimited cheap heat... just run the engine!
Click to expand...
I know that in the case of my Ford CMax Energi PHEV it just doesn't make sense to run the resistive electric heat at or below 32 degrees F. I've had a similar private discussion with owner of a Prius Prime PHEV up in Maine who claims to not even bother plugging the car in over the winter. His gas is 20 cents cheaper than mine and his electricity is 27% higher so one can easily see his point.
 
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