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Bolt EV - a resistive element or heat pump?

41K views 65 replies 27 participants last post by  Steverino 
#1 · (Edited)
Does anyone know what is gonna cool/warm the cabin of a Bolt ? A resistive element or a heat pump ?
 
#6 ·
Not sure but it really doesn't matter; we're just going to have to wait until we see the range is colder weather...Same would go for opposite, what affect would the A/C have on hot climates?
 
#7 · (Edited)
Chevy said, I believe, that the Bolt would have a "more robust" heating system than the Volt.

I did notice, in the options list printout, it shows rear heating ducts, and also lists optional seat heaters for all four seats.

That is all we know so far.
 
#9 ·
Remember the relative battery sizes. Both Volt and Bolt are compact cars, both will take ~about~ the same power to heat up and maintain the cabin temperature. If you use 1KWHr of heat every 10 min in Volt (6KW rate), you just cut your range in half. If you use the same in Bolt, that's a much smaller impact.
 
#10 ·
Despite it having a small footprint, it has the same interior volume as the full size model S so there's more air to heat vs the Volt...The rear vents and rear seat heaters do help a great deal...But we simply won't know until we know; to keep the car 67f when it's 40f out or 0f out, what the impact on range will be...
 
#11 ·
I predict a massive amount of threads about low winter range and poor heating this year. From all brands of EV/PHEVs. :D

It's a pretty safe prediction since it happens every year.

The most interesting might be the Model X. People were complaining about summer range, and it has some significant interior volume and tons of glass.
 
#12 ·
I was at the Chevy dealer today and the parts guy said the Bolt parts catalog is starting to fill in. I asked about the heater and he told me there's no illustration yet, but it appears the car is going to have resistance heating from what he could tell from the catalog.
 
#16 ·
It should be fairly easy to anticipate. EVs and ICEVs will both lose approximately 6% fuel efficiency for every 10F below 70F.

@70F: 238 miles
@60F: 224 miles
@50F: 210 miles
@40F: 198 miles
@30F: 186 miles
@20F: 175 miles
@10F: 165 miles
@0F: 155 miles
@-10F: 146 miles
@-20F: 137 miles
@-30F: 129 miles
@-40F: 121 miles

I'd be interested to see how Tesla Model S are currently doing in those weather conditions. We could probably build a fairly accurate predictive model based on weather conditions.
 
#26 ·
Obviously not. Many factors play into it, but if you'll notice: My estimates were exactly in line with the average losses from 73F to 32F that they listed for the EVs. I do find some of the information they provide a bit suspect, though. I think they are presenting the ICEVs as losing far less efficiency than I have observed in real life. One thing that jumps out at me is that the ICEVs are shown as only losing 4% of the fuel efficiency due to tires and inflation. That definitely doesn't match my experiences.

Also, notice how much energy EVs use for cabin heating. If a large portion of that came from preheating, the loss of range would be significantly less. And I have a feeling that much of that 43% did come from preheating, because their focus was on the total energy consumption.
 
#21 · (Edited)
I have a Leaf, but it is a 2012 model that uses a resistance heater.

I do not use the HVAC it to heat the cabin, as the Leaf has heated seats both in the front and the back and a heated steering wheel as well. Other than the occasional defrost (which can be avoided by preheating while the car is plugged in), the HVAC does not get turned on much.

However, the cold temperatures themselves take a good hit on the battery. Say ~30% range loss when the temperatures drop below -25Celcius, which happens in Ontario Canada.
 
#22 ·
I see an average capacity loss of about 25% from EPA range on my 2014 Volt once temps get down near freezing or below.
Couple that with the usual brisk winter headwinds winds, and the occasional snow/freezing rain storm when you need full heat/defrost, full wipers and headlights... and that 25% loss quickly approaches 40% loss.
With the Volt, if it's nasty out (snow/freezing rain, etc..) I just run the ICE now and let it's thermal waste do some work for me.
 
#24 ·
Like any tool selection, pick the one that's right for the job. For me, the Bolt could lose 50% of it's range in the winter and still be more than adequate for my needs. Otherwise, I'd take the Volt. That's why I think a Volt and Bolt are a great combo for a two car family :)
 
#28 ·
In theory, the Bolt's battery chemistry has a wider temperature window according to GM. We will see, but it is possible it will be less heat and cold sensitive than other cars.
 
#29 ·
I have to assume that the combined heat pumps aren't miniaturized enough and are expensive but in the long run the ONLY way to go for EVs. If you're in California not a huge deal. But in the PNW east of the mountains it is. Since AC is one side of the mechanics needed it's a shame to waste heat when defrosting in the winter for instance. Given what the Japanese have done with this technology one would think it's almost ready for autos.

Heat pumps are just SO much more efficient and at much lower temps than the past. Oh well. I still bought a Bolt.
 
#30 ·
Actually, as battery technology improves, I feel that heat pumps will be less and less necessary. The Bolt EV is a perfect example of this: You can run the resistance heater on full blast and still end up with more range than the Leaf not using a heater at all. When battery densities double and triple, the downside of a heat pump in cold weather and the marginal efficiency improvement will make them not worth the cost and complexity.
 
#31 ·
This isn't meant to be a snarky comment Ladogaboy but before I looked at your location I was pretty sure you were from LA. At just 10-20* a heat pump could save a tremendous amount of energy as the return can be 3-5 times over resistant heating. It makes a LARGE difference in range.

The Volt was easy! Just kick on the motor a little bit and then go back to electric and you could watch the efficiency of the climate control increase and decrease as circulating hot water quickly boosted the heat in the cabin and then cooled off.
 
#33 ·
Sorry if this has already been covered but,, you can't get Heat and Dehumidification at the same time with a Heat Pump system.

Example: the Prius Prime starts the gasser when the Defrost button is pressed. Don't know how the heat pump Leafs operate.
They probably have a resistance heater also in the HVAC system.
 
#34 ·
My home heat pump is set to phase out at -5*. The 'mini-splits' produced in Japan (mostly) go to below 0* now. Efficiencies have improved immensely.

Whether bigger batteries make it somewhat less critical whether you'll make it to any destination in real cold the loss in range is still the same loss for a given amount of heat produced. It may not be a big factor in the LA basin but it's a big factor here. We have further to go for most destinations in more difficult conditions.
 
#35 ·
I'm not a typical LA driver, and I'm fully aware of the impact of resistance heating. One of my trips back from Northern California, I had to travel 160+ miles on a 70 mph freeway in sub 40*F temperatures with fog rolling in. The Bolt EV handled it just fine with 80% battery and the defogger running.

As the batteries get larger and the fast charging infrastructure gets built out, the need for heat pumps, even in cold climates diminishes. That's all I'm saying.
 
#37 ·
You're calibrated to 'cold' differently than I. I go backpacking in those temps!

I do see resistive heat as primitive when the 'heat pump' is already on board for AC but acknowledge that a compact package of controls is an added expense, though in time it will be standard. A compound heat system may be in the cards.

The relative leverage factor of heat pumps puts resistive heat in the catagory of wasteful.
 
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