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Discussion Starter #1
Maybe due to time of year, I only read about people hypothesizing about range loss due to heater use.
I've heard the Volt heater is about 6kw but I assume there is a medium and low setting that uses less.

What about us Californians? How much juice will the air conditioning use?
Second, does the defrost / defog setting run the A/C and heater at the same time (to dry the air) like an ICE car does, making it a double whammy?

Also, while at work, I will have access to (free) 120 VAC charging only.
Can you pre-heat or pre-cool the car off 120 VAC?

I realize 12 amps x 120 volts is only 1.4 kW.
Will the car be able to do limited heating and cooling with this?

Thanks.
 

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A lot depends on where you live.

AC doesn't use a lot of power so long as the ambient doesn't get super hot, and heated seats use very little power. But cold weather reduces the efficiency of the car and there isn't anything you can do about this.

120v won't be enough to precondition your car, but charging at this rate when at work will increase the SOC of the battery enough to take care of heating and cooling needs.
 

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On Volt 1 the heater draws up to 6.5 kw or so and the AC around 2.5 kw (max, maybe more with battery cooling?). Clearly 120 V at 1.4 kw can't keep up. However, the 120 V will keep the battery warm in the winter which helps range (e.g. cold soaked battery at 0F at work kills range), and in summer the AC draw isn't that much more than 120 V can provide. Also, if really hot the 120 V can condition battery.

If you start the car with the App it seems to do a better job preconditioning than with the fob, but honestly haven't paid much attention. Preconditioning will eat into battery range, but you can do it with 120 V or 240 V, but range will drop more over 120 V. A remote start lasts for 10 minutes, so in winter here in iowa this could use up to 1 kwh of battery if not plugged in (assuming heat was run at max, don't recall if preheat will actually max out heater).
 

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I did an experiment last summer when it was 98 degrees and solid sunshine. I plugged the car into 120v power and then started it (really started it, not a remote start) with the AC set to 70 degrees. An hour later, the battery had lost about 1/4 of the charge and the interior was nice and cool. So, it will do a nice job of pre-conditioning. You just don't have enough input power from 120v to prevent some battery discharge. In the cold Nebraska winters, it's perfectly normal for battery range to drop into the lower 20s. It's not so much due to the 6KW heater as it is the fact that the entire car requires more power to overcome cold oil, cold grease, and cold battery cells. The battery heater only warms the battery enough to get it into a safe operating temperature, which is still cooler than the ideal temperature for lithium batteries. Nobody gets great mileage in the cold, it's just the nature of electric cars. Nissan and Tesla have the same problem.
 

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If it's anything like the Spark EV, you should expect a 5-10% hit when using the A/C. Of course the extremes can jack this up. I once parked and charged at a MOMs Organic Market, but the car was in the direct sunlight on a 95 degree day. On the drive after that, the efficiency dropped quite a bit. Parking/charging in the shade is a big plus in the heat.
 

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I have better luck managing the AC and the hit on my range vs HEATING and the hit it takes.

But in a Volt it doesn't matter since you don't have to worry about the loss of range, but a BEV is another story.
 

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Another thing to keep in mind is the temperature spread difference the HVAC system is trying to handle. For most of my AC use, the car is trying to cool, say 85 degree air down to 72 or so. A 13 degree difference. In the winter, it's trying to warm 20 degree air up to 72, a 52 degree difference, 4 times the temperature differential to overcome.
 

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All vehicles use energy to change the interior temperatures, so don't worry that much because everyone does it, but only the few "energy pinchers' want to measure every Watt-second of energy. BTW, a Watt-second is a Joule (whch is the scientifically correct term for energy), and a Watt-hour is 3.6 kiloJoules (kJ). The Chevy Volt battery charge is 57 MJ (megaJoules).

Here in Puerto Rico, everyone uses air conditioning. Sometimes I use conditioned air to save gas (which is cooling air under the condition that the windows are opened).
 

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defrost/defog: If you watch the climate screen on the Gen 1 Volts, you see both the AC and the heater come on when you hit the defog button. The Bolt will have a similar heating/cooling hardware configuration (AC direct-refrigerant cooling-only, separate electric-heated glycol loop for heating), so it will have the capability of using simultaneous cooling/heating for defog. In the auto industry, this is now the preferred way for defog, as it makes the driest air and gets the fog go away pronto. It may be more energy efficient than going heat-only and running the system in defog longer. Note that this simultaneous cool/heat configuration may not be do-able with a heat pump system, as the same refrigerant coil can not both heat and cool at the same time. This could be one reason GM has not yet adopted a heat pump configuration.

AC efficiency: Not sure how the Bolt AC system will compare with the Volt's, efficiency-wise. GM decided to have LG make the AC compressor for the Bolt. LG has a wealth of experience making ultra-efficient variable-capacity AC and heat pump systems in the global "mini-split" heat pump market. They may have included some "secret sauce" in the AC system design that may improve efficiency over the Volt's system.

Heater modulation: If you watch the DIC on the gen 1 Volt when stopped and with the heat on, you will see the kW draw ramp up and down as the heater steps through various stages to maintain the glycol temperature. So yes, it either had a multi-step or full modulating heating capacity.

120 volt pre-condition. At least with my gen 1 Volt, my experience has been that when you hit the "pre-condition" button on the key fob, it starts up the heat or AC as appropriate and operates for a 15 minute cycle regardless of what voltage charger is plugged into the charge port, or if it is plugged in at all. The advantage of being plugged into the 240 V charger is that it can provide as much juice flowing into the battery as the battery is using to pre-condition. It takes longer for the Volt battery to recover that used juice if plugged into a 120 V charger, and of course, can't recover any juice at all if it isn't plugged in. Typically, using 3-4 kW for 15 minutes of pre-conditioning will burn off about 1 kWh of charge from the battery. Your call whether that is a good investment or not.
 

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The gas engine does a great job heating the car. Push hold until the cabin is warm.

I dont know if it will use the heat to warm battery to optimum but seems so.
 

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defrost/defog: If you watch the climate screen on the Gen 1 Volts, you see both the AC and the heater come on when you hit the defog button. ... In the auto industry, this is now the preferred way for defog, as it makes the driest air and gets the fog go away pronto. ...
It has always been the preferred way to defog, at least ever since I started driving over 40 years ago. Every car with A/C that I've ever owned works this way. The only cars that used nothing but heat were cars that weren't equipped with A/C.
 

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Discussion Starter #12
In near freezing and below, cars only use heat.
A) cold ambient air is already dry by nature
B) your a/c evaporator will ice up, blocking air flow
 

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Took a test drive on a 70 degree day. The interior was hot from sitting parked with windows closed.

The air conditioning kicks a$$ in this car.
The air was cooled rapidly and the velocity & volume of air out of the vents was impressive.
 

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The AC should be completely variable, just like on Volt.
If you only need a little cooling, it will run at ~500W. If you need max cooling, it will run at 2500W+ (whatever it's max rating is. If you need something in between, it will reduce to that level.
So while it may require say, 3000W at max, once the temp setpoint is reached, it will dial back to a much lower level to maintain. So you likely could precondition on L1 and leave with a full battery, but you're going to need to plan quite a while ahead of time for it to recharge. Definitely L2 suggested.

defrost/defog: If you watch the climate screen on the Gen 1 Volts, you see both the AC and the heater come on when you hit the defog button. The Bolt will have a similar heating/cooling hardware configuration (AC direct-refrigerant cooling-only, separate electric-heated glycol loop for heating), so it will have the capability of using simultaneous cooling/heating for defog. In the auto industry, this is now the preferred way for defog, as it makes the driest air and gets the fog go away pronto. It may be more energy efficient than going heat-only and running the system in defog longer. Note that this simultaneous cool/heat configuration may not be do-able with a heat pump system, as the same refrigerant coil can not both heat and cool at the same time. This could be one reason GM has not yet adopted a heat pump configuration.
Sure you can. That's basically exactly how modern energy-efficient clothes dryers work.
They cycle the air through the hot side of the heat pump to warm it up, through the clothes to pick up moisture, then out the other side and across the cold side of the heat pump to condense the moisture out, then back to the hot side and repeat the loop.
The only "hard" (but not that hard) part is dealing with a system where typically one side is internal and one side is external. You'd need a way to make both internal and the one side is capable of connecting to an external rad sometimes, but not always. Basically how the volt's blended HVAC system works.

 
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