LeftieBiker said:
It draws more and more
power when it gets colder. Resistive heater adds to get more heat.
Fact is that heat pump draws up to 2500W (usually up to 2200W stable) and generates about 2300-2600W of heat near -14C
I see temps in two photos but can't see them in the individual LeafSpy shots. Is the outside temp -3C? If so, then that's still in the heatpump's "comfort zone." I think that the reading may be misleading - that the heatpump ("A/C") reading is somehow including resistance heat. Even if what you say is fully accurate, though, the effect is the same: cars with the heat pump draw as much power for heat at 0 F as those without. I know that home heat pumps include a resistance heater to supplement them, so the question is whether the PTC heater is a completely separate system, or if it "feeds" heat to the heatpump at low temps.
Between -5C -3C on all those pictures.
Jep, it is heat-pump's "comfort zone". AC reading is not including resistance heat AT ALL. Only energy that goes to compressor inverter. Vehicle does display climate draw as the sum of those two.
In Europe air-air heat pumps almost never have resistance heater included, I suspect same is in US (as the choice for those devices there is much worse). Air-water or ground-water pumps do as they are expensive and are "all-in-one" solution for heating. But normal heat pumps, (like on Leaf), would suck 1500W of electricity and generate 1,0-1.1x 1500W of heat at -40C :lol: Not with resistance heater! Just apply first law of thermodynamics: use 1500W of energy/power to do some work. If extra heat is not captured after evaporation at outer condenser you just get the same amount of energy when gas gets compressed as heat.
Leaf's PTC heater is standalone system. Electrically. They are very close to each other and both get the same air (according to diagrams amount of airflow can be adjusted between them, I'm not sure that is correct).
What I would really like to see is a comparison of the power draw with the SL/SV system and the S system at several temperatures between 40 F and 0 F. I realize there would have to be some sideboards such as a particular setting of the auto controls. I am trying to ask the practical question of what the SL/SV system is worth as far as reducing battery draw and increasing range compared to the resistance heater in the S. The buyer pays a significant premium for the SV/SL. What are the benefits - or at least this particular one?
Precise comparision is not possible. Heat pump is sensitive to more things than only air temperature. Things like air humidity, frost buildup, airflow on both condensers, interior condenser input temperature, vehicle speed. And some more.
What are the benefits - hybrid heater heats up cold cabin MUCH faster at temperatures between 20F-60F. Heat pump and PTC heater together can generate cabin heat at 6-10kW rate at cold vehicle startup. Even Tesla can't do that. This adds comfort.
Range drop during winter is on average only a third compared to 2011 Leaf.
I can drive 1km per 1% in 20F weather with warm cabin. So about 100km at 55mph. I can do 120km in summer.
Heat pump is more effective if it runs at moderate rpm (something like ICE engine). Therefore after cabin is at stable temperature
heat pump efficiency goes to where it should be. And PTC is usually not used. This is why I recommend choosing lowest temperature setting in the beginning. Then slowly turn it up if gets uncomfortable.
Heat pump also makes sense in urban traffic. To keep cabin warm it requires almost* constant amount of energy per unit of time (not distance). If we cut heating consumption in half we waste much less per distance travelled.
Imagine PTC heater draws 3kW per hour, hybrid heater 1kW per hour (same cabin temperature). If we drive 10mph average with 4miles/kWh we run down 21kWh battery like that:
With regular PTC 3...6...9 kWh power for 3 hours of heat, 10 mph 3 hours 30 miles, 30/4= 7,5kWh on driving. 9kWh on heating, 16,5kWh, 82% of battery. Can theoretically drive 36,3 miles.
With heat pump 1...2...3kWh power for 3 hours of heat, 10 mph 3 hours 30 miles, 30/4= 7,5kWh on driving, 3kWh on heating, 10,5kWh, 50% of battery. Massive difference. Can drive 60 miles!
Those who have PTC heating only tend to keep cabin colder on longer trips to minimize range loss. With hybrid heater in comfort zone it is not a topic any more. It acts like 60+kWh Tesla. Due to the fact that there is more range to start with range loss due to heating is not a noticeable problem. This is why Tesla doesn't even offer heat pump. Also during longer trips battery chemistry heats up and range loss due to cold battery is reduced even more.
*the faster you drive the more are windows cooled down. That also cools down the cabin.