Evoforce
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Re: Bolt winter performance, an ICE comparison

Tue Feb 13, 2018 2:05 am

LeftieBiker wrote:
EldRick wrote:Let me summarize: heat-pumps don't work worth a darn in weather colder than freezing, which afflicts most of the US.
That is why every heat-pump home furnace in the world also has a secondary heat source: a hot-wire electric heater component, to take over from the heat-pump when it's cold out.
So there is very little point in a heat-pump in a car. It would add mechanical components that add cost and wear out and break, and would only save a bit of energy for those in California-mild climate.
The only reason the Leaf has one is because they had a tiny battery, and needed to save every possible watt-hour to provide any interior heat at all.


Let me summarize: you are mistaken. Heat pumps are useful down to almost ten degrees below Freezing, and this means that they will be useful for about 90% of the year - 100% in many climates. GM chose to do without one to save themselves money, not because "there is very little point in a heat-pump in a car." It's kind of sad to see people rationalizing every mistake or cheap-out that GM commits. The Bolt is a very good little car. If they fix the seats, road noise, and wasteful heating system it will become a great little car.


And let me add... we need more quick charging infrastructure.

SparkE
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Re: Bolt winter performance, an ICE comparison

Tue Feb 13, 2018 6:57 am

What we *really* need are vehicles that support ultra-fast charging (at least 150 kW up to, say, 50% SoC).

IMO, The most important thing to make BEVs more palatable to more people (especially those with only 1 vehicle) is faster charging capability in the vehicle. When cars are widely available that can charge at 150 kW, BEVs will get rid of the true major holdback for people. That "but what if I want to drive to ..." is as much about (if not more-so) having to wait for 60 minutes to add 150 miles of range than it is by "lack of charging stations". It is possible today to drive from California's northern border to its southern border in a Bolt, as well as drive to Las Vegas and Reno. There are, today, CCS charging stations already sited (sites chosen) and approved and budgeted to make it even easier, and possible to easily drive into AZ. But there are currently NO vehicles that will charge at 150 kW (350 amps) using CCS. Heck, *I* take an ICE vehicle if I want to drive more than about 300 miles. It's not that I *can't* recharge - it's that I don't want to wait at the dam station for the electrons drip-dripping into the battery. If I could add 120 miles in 15 minutes (e.g., a 300 amp draw @ 400V) - then yeah, I *would* use my BEV to drive to L.A. or San Diego or Reno or Eugene, OR. It isn't lack of *stations* holding me back - it's lack of capability in the *vehicles*. By the time 150 kW-capable CCS vehicles are generally available, there will be a substantial network of charging stations installed and ready to charge them. In California, they are already planned. And that isn't counting the 2 OTHER networks (not funded by CEC) that are being put in place over the next 2-4 years : VW's "dieselgate" network, and Ionity (which are going in all over the country).

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oilerlord
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Re: Bolt winter performance, an ICE comparison

Thu Mar 22, 2018 5:53 am

GetOffYourGas wrote:
I'm not sure how that relates to the question. Are those the tires that OilerLord is using? Did I miss where he mentioned that?


I have a set of 225-50/R-17 Pirelli-Winter SOTTOZERO 3 tires on the Benz. They stop well in winter...but from experience, I think these may be HRR tires. I've had a dramatic reduction in range with these tires. I guess I might have been able to find skinnier tires that would fit, but I think it's best to follow the recommended sizes on the door label. (Our) Costco wouldn't install any size outside of what the manufacturer recommends for the car.
2014 Mercedes B-Class Electric Drive
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My 9.2kW DC Solar: https://easyview.auroravision.net/easyview/index.html?entityId=7466210

winterescape
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Re: Bolt winter performance, an ICE comparison

Sat Dec 08, 2018 7:26 pm

LeftieBiker wrote: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.



A very interesting paper on optimal cabin heating for an EV that evaluates the design trades...

https://www.sae.org/news/2018/05/new-be ... on-studies

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