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Discussion Starter #1 (Edited)
Although I am certain this topic has been discussed in the past, I am intrigued that it has not gained the level of attention and discussion as did loss of range when heating in the winter.

My commute is nearly ideal for my 2013 Volt. Eighteen miles each way in stop and go traffic. Since I purchased my Volt in January, I have had no trouble making it to and from work on electric power alone, with 7 miles of range to spare. After about 4800 miles, I have used 20 gallons of gas for an average of 244 mpg. Gas was used primarily on out of town business trips, demonstrating the benefit of the Volt: Travel as far as you want with no concern over finding refueling stations.

But the winters in Phoenix are understandably mild, and having heated seats, I seldom used cabin heating even on the coldest days (38 F, brrr).

Now high temps are over 110 F each day, with morning temps around 80 F, so the AC is getting a workout. I find It interesting to watch the kw meter. Without the AC, sitting at stop light the meter would read 0.5. Starting my commute home with climate set to Comfort and 75 degrees. the meter is reading 5 kw. My range is down to about 32 miles, so the last 4 miles of my commute home is on ICE.

As an engineer and car guy, I always knew AC drew power. Now I can see precisely how much energy, and experience the impact on my energy use in a visceral way.

The knowledge will not change my climate settings, though :cool:
 

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It's certainly been discussed - but as you say, it gets less attention, most likely because the effect isn't nearly as pronounced - even in Phoenix type weather, you lose maybe half as much as someone in a midwestern winter will.
 

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Just be grateful that GM bothered to engineer a more efficient 3phase Alternating Current AC compressor just for use in the Volt;)
 

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The weather has been brutal out there. The guys in the BMW i3 forum are reporting significant loss of range and trouble with the AC keeping up. The best thing you can do is pre-condition whenever possible and park in any shade you can find. Hopefully the current heat wave won't last.
 

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The main reason you don't hear as much about the range loss is because it is less severe than with cold weather. With cold weather, your mileage is impacted by increased climate usage, increased drag from air density, and increased rolling resistance from tire pressure loss. In hot weather, you only have to deal with one of those issues.

Out of curiosity, do you have window tinting? Almost everyone I know from AZ says that window tinting is a must, but some window tints are proven to be far more effective at blocking out heat.
 

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Discussion Starter #6
Out of curiosity, do you have window tinting? Almost everyone I know from AZ says that window tinting is a must, but some window tints are proven to be far more effective at blocking out heat.
The windows are tinted but I don't know what kind. The Chevy dealer added it (and wanted to charge extra for it) because the car came from out of the area, and, as you say, everyone here needs it. I suspect the tint is not premium.
 

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The windows are tinted but I don't know what kind. The Chevy dealer added it (and wanted to charge extra for it) because the car came from out of the area, and, as you say, everyone here needs it. I suspect the tint is not premium.
That sucks. Hopefully, you didn't have to pay extra. It would be interesting if you can see how it compares to a premium tint, because it might be worth replacing.
 

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If you go to the hvac page on your display, it shows what % of power your system is using. The other day when it was 117 degs, my car was parked in the shade and it still was using 97%. I park in our shop in the summer which is swamp cooled, temps around 85 degs. Driving out of the shop, the ambient temp display at 85 deg, the hvac would be at 38% but as I drive within 1 mile and the ambient temp sensor starts to update, the % will really start to rise when it hits 100 degs, from there 1deg adds about 2% to the hvac even if the battery temp has not changed.
 

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When parking in the St Louis summer heat, I always drop all four windows and drive for about 5 minutes or so to vent the cabin and THEN turn on the AC. I won't use the AC to pull the heat out of the car initially. You can easily drop the cabin temp 20 to 30 degrees that way. Then the AC isn't having to work so hard the rest of the way.

But AC is still more efficient than the northern folks having to heat in the winter. I can and have lost 50% of my AER. And FTR right now my Guess-O-Meter still starts off at 49 miles here in St Louis. But that will end when our real summer arrives. But AC is far more efficient that heating.
 

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From what I've noticed with the Mygreenvolt/Torque Pro apps, once the HV battery temperature hits 90F, the TMS will kick on. Sitting out in the sun on a black asphalt parking lot in 100+ temps for 8+ hours will surely heat up the HV battery past the 90F mark.

My question is: does the TMS ever kick on while parked and unplugged? Not sure if we've ever seen a definitive answer on that question.
 

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Here in Florida the guessmeter on my 2015 volt reads 50ev miles, but looking at my kWh used screen it shows I have actually have 56ev miles, and this is every full battery charge
Life is good!!!
 

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If you want to keep car at 75 F, on a 110 F day, you need to drop the temp 35 F.

In winter, if it is a 0 F day (high) you need to heat the air 75 F.
 

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If you want to keep car at 75 F, on a 110 F day, you need to drop the temp 35 F.

In winter, if it is a 0 F day (high) you need to heat the air 75 F.
That's certainly true, but the overall picture is worse than that. With air conditioning, you generally get 2 or 3 times as much heat moved as the energy you spend moving it. The Volt's resistive heater is pretty efficient, so it gets almost as much heat delivered to the cabin as the power it consumes. Thus, in your example instead of looking at twice the power you're looking at four or five times as much power.

(Of course, most folks don't actually heat the cabin to 75F in the winter - if the car actually managed that the people would be very uncomfortable in their winter coats...)
 

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I'm probably going to state nothing new here, but down south we get heat and humidity. Yanking a car interior from 115-135 average temp and 70-85% humidity down to something resembling comfort means pulling a lot of heat out of the thermal mass of the cars interior.

I've played with remote thermometers and a variety of different plans to keep my car cooler and in all seriousness the single best bang-for-the-buck is to get your side and rear windows tinted and then use one of those stupid windshield shades.

Barring that, I know several people who have white car-covers and will throw them over the car for the day.
 

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When it gets over 90F here in Texas, I just say eff-it about using gas and pre-cool the cabin. My commute is so close to my ELR's best range that I rarely get a full commute on EV only anyway. Might as well be comfortable.
 

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When parking in the St Louis summer heat, I always drop all four windows and drive for about 5 minutes or so to vent the cabin and THEN turn on the AC. I won't use the AC to pull the heat out of the car initially. You can easily drop the cabin temp 20 to 30 degrees that way. Then the AC isn't having to work so hard the rest of the way.
I do this as well.
Our parking lot at work is a fair ways back (visitors parking up front, then a lane to drive) so I hold the window down button and see my windows go down in the distance. By the time I get to the car, much of the hot air is gone and the car is much more pleasant.
I would never keep that bottled up inside and then try to cool it with AC.
Even if it's 100+ outside, it's going to be even hotter inside if it's sat out in that all day. Always better to vent the car first.

From what I've noticed with the Mygreenvolt/Torque Pro apps, once the HV battery temperature hits 90F, the TMS will kick on. Sitting out in the sun on a black asphalt parking lot in 100+ temps for 8+ hours will surely heat up the HV battery past the 90F mark.

My question is: does the TMS ever kick on while parked and unplugged? Not sure if we've ever seen a definitive answer on that question.
Yes.
Cooling is the only standby TMS function - it will not heat if not plugged in. But will cool if the SOC is above a certain threshold. (40-50% IIRC). If low battery charge, it won't turn itself on.
 

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That's certainly true, but the overall picture is worse than that. With air conditioning, you generally get 2 or 3 times as much heat moved as the energy you spend moving it. The Volt's resistive heater is pretty efficient, so it gets almost as much heat delivered to the cabin as the power it consumes. Thus, in your example instead of looking at twice the power you're looking at four or five times as much power.

(Of course, most folks don't actually heat the cabin to 75F in the winter - if the car actually managed that the people would be very uncomfortable in their winter coats...)
Resistive heating delivers less BTU per Watt than a heat pump, which an air conditioner is. I think this is the point in the difference between range loss in hot weather vs cold weather. It does matter what the temperature difference is, but heat pumps are still recommended for efficiency when heat is required. The big down side is the cost of the heat pump vs resistive heater, but is negated when air conditioning is required anyway. Still, the Volt is heated with a resistive device.
 

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Resistive heating delivers less BTU per Watt than a heat pump, which an air conditioner is. I think this is the point in the difference between range loss in hot weather vs cold weather. It does matter what the temperature difference is, but heat pumps are still recommended for efficiency when heat is required. The big down side is the cost of the heat pump vs resistive heater, but is negated when air conditioning is required anyway. Still, the Volt is heated with a resistive device.
I'm confused. As best I can parse this, I think you're making my point again with different words - heating in the Volt is less efficient than A/C because of the equipment used, in addition to needing to generate a lot more heat and having higher losses due to the larger temperature differential.
 

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Discussion Starter #19
The weather has been brutal out there. The guys in the BMW i3 forum are reporting significant loss of range and trouble with the AC keeping up. The best thing you can do is pre-condition whenever possible and park in any shade you can find. Hopefully the current heat wave won't last.
One of the things I like most about domestic cars is their powerful AC. I had a BMW 3 Series just before my Volt. The AC in the BMW couldn't keep up with the AZ heat over 90 degrees F, but my Volt does just fine in 115 F heat.
 

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Discussion Starter #20
Resistive heating delivers less BTU per Watt than a heat pump,
Speaking as a mechanical engineer specializing in HVAC design, I can agree that this is true ... but ...


... , which an air conditioner is ...
This is not true. An air conditioner is an air conditioner. A heat pump is an air conditioner in reverse.

Energy is energy. It takes more energy to keep a car at 70 degrees above ambient than to keep a car at 30 degrees below ambient (ignoring solar effects for simplicity's sake). In the winter the difference in the average ambient temperature and the desired average interior temperature is much greater than that difference in summer. Thus, more battery drain in winter. A heat pump would help, and frankly, since they already have AC, I am surprised the engineers at Chevy didn't incorporate a heat pump into the cabin climate control. I suspect they had a good reason, like need for battery conditioning or some such.
 
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