Thank you, Oilerlord. I'm going to be posting here less, now that I'm sure I'll be leasing a 2018 Leaf rather than a 2017 Bolt, but it's hard to resist talking about things that are applicable to all EVs. Like this:
I have the same setup at home and i'm convinced that most people that are desiring a heat pump in the Bolt don't have one at home or have never used one. Heat pumps heat slowly and if it was cold outside, 32 or below, the air coming out of your vents would not be very warm and cozy like you want on a cold day. Especially if it was outside and the heat pump had to warm all the vents up slowly. When my heat pump at home kicks on when below 32, it takes a long time to just get the ducting warm and you never get "hot" air out of the vents. It raises the temp of the input air by 10-12 degrees at most when in the lower digits, if that temp outside is in the teens, less. I have mine set to switch over to gas at 38 due to price of natural gas here, it's just not efficient to heat with heat pump below that. The other thing would be defrost, heat pump won't pull moisture out of the air so i think when the defrost is on, you'd need element heating and then A/C which defeats a lot of the purpose of using heat pump. That being said i love my heat pump at home for mild weather but I honestly don't see the cost/benefit of it in a car. That is a lot of complexity there to break when if you truly think about it, how much efficiency would you really gain when considering everything? (window defrost, heat pump defrost mode in <32, cold weather, how much you use the heat in mild weather).
EV heat pumps are ALWAYS
, as I have written before, combined with PTC (resistance) heaters in EVs as well. The two work together, varying their contributions according to what is best for a given situation. You say that I haven't taken into account diminished heatpump efficiency below 32F. In fact I have, but I'll make it more clear. Leaf drivers have found that the particular setup we have in our heatpump-equipped Leafs stops giving a range advantage over PTC-only Leafs at about 14F. It's not a matter of the heatpump starting to use more energy than the PTC - that never happens. Instead, the PTC contributes more and more heat to the system, until at about 14F it is providing the lion's share of heat. The heatpump shuts off at about 7F, IIRC, but by then you don't notice any extra range from it.
Here are my observations about Leaf heatpump usefulness:
* 45F and above: the car loses no more range to heater use than it does in hot weather to A/C use, generally two or three miles less on the Guess O Meter. This is vastly better than using just PTC heat!
* 45F - ~39F: roughly 5 miles of range lost, even though the GOM doesn't usually reflect this. Still much better than PTC only.
* 39F - ~30F: roughly 7 miles of actual range loss. Still only about 2/3 as much power used, compared to PTC.
* 30F - 24F: roughly 10 mile range loss. AT this point you know that you're losing lots of range to heat, but it is still less than PTC-only Leafs.
* 24F - 14F: roughly 15 mile range loss. A small advantage remains, but it is just a few miles of range.
*14F and lower: indistinguishable from PTC-only heat. Roughly 20 miles of range (about 33%) lost compared with no heat. This is from a total range of maybe 65 miles, real world.