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Discussion Starter #1
Trying to calculate the power required to run the 360V Coolant Heater. I seem to have mistakingly read that when connected to the 240V grid, no battery consumption would occur.

So I assume coolant circuit I is > 10 because today I turned on the resistive heater on my MY17 when connected to the 240V grid and I lost about 100 watt hours of battery over about 10 mins. Probably another reason a 3.6 kWh charger is too small.

Anyone know what the max current draw is on 360V coolant heater or the coolant heaters resistance?
 

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Looking at the power gauge with car stopped you will see about 6kw max for heater in comfort, about half that for eco. The heater ramps down quite quickly as the car warms up. It will draw 1-2 kw intermittently to maintain a cabin temp of 74° in low 40°'s temps. So yes, the heater will overpower a 240v evse at least initially. You need about 10-15 minutes of "recovery time" after a preheat to bring the battery back to full. But hey, you have a gas engine, so who cares?
 

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Trying to calculate the power required to run the 360V Coolant Heater. I seem to have mistakingly read that when connected to the 240V grid, no battery consumption would occur.

So I assume coolant circuit I is > 10 because today I turned on the resistive heater on my MY17 when connected to the 240V grid and I lost about 100 watt hours of battery over about 10 mins. Probably another reason a 3.6 kWh charger is too small.

Anyone know what the max current draw is on 360V coolant heater or the coolant heaters resistance?
Find the heater element, open the contacts, and insert a DC ammeter in series. That will get you the exact current draw. Oh, and while you are on it, remember that it has a high DC voltage so keep your body parts away while measuring.
 

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Find the heater element, open the contacts, and insert a DC ammeter in series. That will get you the exact current draw. Oh, and while you are on it, remember that it has a high DC voltage so keep your body parts away while measuring.
Right, and make it a big ass DC ammeter with HV capability.

Or sit in your car in park, with the power meter displayed and turn the heater to max, on and off.
And call that kW display, "Good enough".
 

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Right, and make it a big ass DC ammeter with HV capability.

Or sit in your car in park, with the power meter displayed and turn the heater to max, on and off.
And call that kW display, "Good enough".
Or use something like Torque or DashDAQ to get a more precise number out of the car's onboard instrumentation.
 

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Max(Comfort) Heat was 6kW on Gen 1 and is closer to 7kW on Gen 2 Volt, but that's really not as important to your question.

A 10 minute precondition can take up to 10 additional minutes to recover depending on how much power was used.

In ECO mode, the heater will draw closer to 3kW, allowing an L2 EVSE to restore power about as quickly as it's used. We know this can go without discharge at all on Gen 1, and I assume Gen 2 would be the same.

All this to say that you would need to start the car with heat in ECO mode rather than use preconditioning shortcuts in order to have full battery available without delay.
 

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Trying to calculate the power required to run the 360V Coolant Heater. I seem to have mistakingly read that when connected to the 240V grid, no battery consumption would occur.

So I assume coolant circuit I is > 10 because today I turned on the resistive heater on my MY17 when connected to the 240V grid and I lost about 100 watt hours of battery over about 10 mins. Probably another reason a 3.6 kWh charger is too small.

Anyone know what the max current draw is on 360V coolant heater or the coolant heaters resistance?
Just sit in the car and watch the power meter.

If it is anything like the Gen 1, you will typically lose around 0.2 to 0.3kWh in the first few minutes as it dumps a stack of power into the heater circuit beyond the 3kW the on board charger can deliver. It'll then remain stable SOC for another 10 mins or so as the power drops to around the maximum of the EVSE, then once the heater starts cutting in and out as the car reaches thermal equilibrium then it'll top the battery back up during the 'off' phases of the heater's cycling.

When I do this in my Gen 1 to get heat into the car and the battery pack I will leave it on a low fan at 23C for an hour. It doesn't really use up more energy by being on longer because once it is heated up it only uses around 1kW, so even if you run it for an extra half hour over the minimum it's 0.5kWh. Nothing in the scheme of things. But the benefit of leaving it on for so long is that when you come to unplug it, not only are all your windows totally clear and dried out but the car will be fully charged as the charger can then keep up easily with that 1kW power load.
 

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The draw is massive. The worst is when I am driving at low speeds and need to use defog. I've seen up to 9 kW of continuous draw as it runs the heater and air conditioner simultaneously.

Chevy sort of dropped the ball with the HVAC in electric mode IMHO. Using more power to keep the windshield clear than you use to keep the car rolling down the road is absurd. For reasons I don't understand, the car defaults to open circuit circulation even when using the electric heater, which is a bit like trying to heat your house with all of the windows open. If I drive this car like I would drive any other car in the winter (75 mph, heat blasting, just like the other 99% of drivers on the road around me) The range would be down in the 20's and the amount of power plant emissions caused would make me about as efficient as a typical modern full size pickup truck. For this reason, if I need to run the heater I run the engine.

All of this makes it obvious why Chevy conceived ERDTT. Run the engine in cogen just enough to provide space heating, and fill in the rest with electric power. You will find that the amount of gas you burn in ERDTT is half of what it would be on a reasonable length trip if you simply press recirculate, but this leads to annoying windshield fogging which has to be intermittently cleared by switching to open circuit for a moment. It would be a simple software update to automate this, or alternatively they could have just installed an electric windshield, a feature which should really be standard on EV's.
 

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Discussion Starter #9
Thanks for all the info.. I do plan on Pre-Conditioning and wish the Volt had at least a 6 kWh charger to decrease the gap.
 

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Thanks for all the info.. I do plan on Pre-Conditioning and wish the Volt had at least a 6 kWh charger to decrease the gap.
I only have 120V charging at the house I am renting, so pre-conditioning uses battery power no matter what on my car. With the "cold" weather we had over the weekend, (daytime 60's, over night high 20's) I didn't need pre-conditioning for my drive into work. I drove into work at 5:00 PM without having to use heat or AC with around 65F ambient temperature. Leaving work temperature was around 28F and I did about 6 min of pre-conditioning. That was enough for the interior of the car to be toasty warm and all windows clear. I don't have auto de-fogging turned on, so my HVAC system defaults to recirculate in cold weather, and I made my drive home with HVAC set to 70F in eco mode. My daily driving range with my commute in summer is 58 miles using AC as needed, and driving the speed limit (55 mph), under current conditions on the same commute driving as described my range is 45 miles. Since my total commute round trip is 39 miles I can drive in comfort without using gas :) With my old 2011 (RIP) I would have been burning gas just from the loss of battery efficiency on a 39 mile round trip in the cold even without running the heat, I love my 2016 :D

Keith
 

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Thanks for all the info.. I do plan on Pre-Conditioning and wish the Volt had at least a 6 kWh charger to decrease the gap.
FWIW, a 6kW Leaf on preconditioning will still run down the battery before charging it back up. You'd think it would be a simple case to divert the charger output to the heater, but it seems manufacturers build their cars in different ways. I don't know why. I suppose one benefit is that by using and recharging the battery it helps warm it up ready for use?
 

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The Gen 1 Volt is 6-7kW max draw for heat/defrost etc. I read somewhere that this was increased in the Gen 2 to something like 9kW.

So yes, you'll use more than the 3.6kW charger can supply, but you probably still consume less by pre-conditioning while plugged in than not.
 

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I wish the precondition setting was more flexible and a little be more custom for the car. I wish we could precondition at like 1kW for like 30-60 minutes to really get some heat into the coolant and then draw that heat back out while the car was moving. The cabin gets decently warm under the current settings but cools down pretty quick if the precondition shuts off and it's more then three or four minutes before you get into the car. If you think about a little space heater that you can plug in they can get fairly warm. If all that was directed right toward heating the coolant (and from my understanding the coolant is somewhat decently insulated from the cold) ~1kW might be enough to overcome 20 to 30F temps and store a pretty nice amount of heat in the coolant.
 

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Agreed 1200 watts would be enough to heat the coolant loop so you had heat as soon as you launch
 

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Max(Comfort) Heat was 6kW on Gen 1 and is closer to 7kW on Gen 2 Volt, but that's really not as important to your question.

A 10 minute precondition can take up to 10 additional minutes to recover depending on how much power was used.

In ECO mode, the heater will draw closer to 3kW, allowing an L2 EVSE to restore power about as quickly as it's used. We know this can go without discharge at all on Gen 1, and I assume Gen 2 would be the same.

All this to say that you would need to start the car with heat in ECO mode rather than use preconditioning shortcuts in order to have full battery available without delay.
It maybe the converted OEM L1 to L2 charger for my 2017 Volt is not quiet saturating the 3.6 kW charger (it charges roughly 2.88 kW), I still have to let the battery top off for 10 minutes for 10 minutes of preconditioning. Looks like precon always dips into the battery first and doesn't draw directly from the EVSE to save on the battery drainage.

FWIW, a 6kW Leaf on preconditioning will still run down the battery before charging it back up. You'd think it would be a simple case to divert the charger output to the heater, but it seems manufacturers build their cars in different ways. I don't know why. I suppose one benefit is that by using and recharging the battery it helps warm it up ready for use?
The Leaf also drains battery first over an EVSE source? That's so bizarre. I don't buy the warming of a battery to get it to ideal operating temps. They could warm the battery along with the cabin. Sure, it eats more power, but it guarantees you have max range when you walk out to your car even while it's still preconditioning. I really like the ideas above from rmay635703 and acarney about using just 1 kW from the EVSE to warm everything up over a longer period.
 

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FWIW, a 6kW Leaf on preconditioning will still run down the battery before charging it back up. You'd think it would be a simple case to divert the charger output to the heater, but it seems manufacturers build their cars in different ways. I don't know why. I suppose one benefit is that by using and recharging the battery it helps warm it up ready for use?
Is this a 6.6 kW capable Leaf on a fast 240V EVSE?

I don't have much experience with it, but it seems like Tesla doesn't run the battery down when connected to an 8 kW source.
 

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The Leaf also drains battery first over an EVSE source? That's so bizarre. I don't buy the warming of a battery to get it to ideal operating temps. They could warm the battery along with the cabin.
How could they do that? There is neither water nor air cooling on it, so how could they heat it? The only way is to pass an electric current through it.
 

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How could they do that? There is neither water nor air cooling on it, so how could they heat it? The only way is to pass an electric current through it.
I believe that most newer Leafs have a battery heater unit - just no cooling.
 

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The Volt is liquid cooled, right? But I believe the coolant loops are separate, possibly to keep from over heating the battery while the engine is running? Either way, low and slow heating of a lot of coolant (we have what like 12 liters of coolant between the battery and the cabin loop?) might have been an effective way to store a lot of energy that would last the first five or ten miles. If you brought that battery up to 80 or 90 degrees slowly and brought the cabin coolant loop up to 80 or 90 degrees over the course of an hour or something while not using any on board energy and had the active shutters closed I would think that would keep the battery warm for a couple hours before it dropped back down to 30 or 40 degrees and probably would exchange enough heat back into the heater core for five or ten miles of warming the cabin, then the heating unit could start in the lowest power mode and just keep things going. Most trips are probably somewhat short trips around town or to work and that might drastically (50-100%) reduce the amount of heating energy needing to come right out of the battery pack.

I can never seem to get the coolant temp (I'm not sure which the dash displays, battery or cabin loop) above like 60 degrees without the engine on when outside temps are 30 to 40 degrees. Still, even after a couple hours I'll return to the car and the coolant temp will be at least 5 to 10 degrees warmer then the outside air temp, so it must hold it's heat somewhat decent. I've got to believe packing energy into there and bringing it to the top of it's optimal range while plugged in on building power would stretch out as much as possible the length of time before needing to use onboard energy to maintain temps.
 

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You'd think it would be a simple case to divert the charger output to the heater, but it seems manufacturers build their cars in different ways. I don't know why.
Technically, it does.
Electricity follows the shortest path/least resistance, so if there is electricity being drawn to the heater unit over the HV circuit, electrons fed by the charger are immediately going out that path instead of the 'harder' path through the battery.
This ensures there is always enough energy to power the heater in excess of the charger input power. If there's excess, it is dumped to battery (charges), if there's not enough, it is drawn from battery to meet the needs of that heater (and anything else in use on the HV circuit at that moment).
The same principle is in use with the engine cycling in series mode - electricity generated is sent to the HV circuit by the generator.
if it is needed by the vehicle, it is gobbled up immediately (most efficient electrical path). If there is excess, it is dumped in the battery. If there isn't enough, electrons are pulled from the battery.

I suppose one benefit is that by using and recharging the battery it helps warm it up ready for use?
A side benefit, but likely not the primary purpose. They have dedicated heating units that can warm it up much faster
 
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