Gen 2 Engine Running Due to Temperature
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If you choose the deferred option in the menu it does not come on till 15 deg f.
You could always check the owners manual...
https://www.chevrolet.com/content/d...rolet-Volt-Electric-Vehicle-Owners-Manual.pdf
KNS
you can defer engine heat by 10 deg c on gen 2
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In my ignorance as a newbie, I didn't realize this aspect of my Gen 2. Engine came on while it was in low 20s (deg F) last week, and I was a bit surprised. What is the reason GM designed it to do this? Does it have anything to do with maintaining a certain minimum temperature for the battery? It's gonna get a whole bunch colder around here over the next few months.
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ERDDT is just for cabin heating. It does nothing for battery temp.
Think of it as a gas burning stove under your hood.
Endless threads on this subject.....
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There is an option just like the 2013-2015 Gen I Volts. It's just called something different. "deferred vs. very cold" setting.
We have had a few mornings in the 20F range here. I still haven't seen ERDTT in my 2017 LT yet. But we haven't hit 15F here yet.
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I have an LT model and this option is there. It's an option on all Gen II Volts.
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243 Posts
The engine running has benefits for the battery also. Keeping it at the proper temperature. See article:
http://gm-volt.com/2016/01/14/cold-weather-pre-heating-engine-assisted-heating-procedures/
http://gm-volt.com/2016/01/14/cold-weather-pre-heating-engine-assisted-heating-procedures/
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I don't see where the battery TMS is linked to the engine in any way.
Look at the diagrams in this official GM-Volt technical page:
http://gm-volt.com/2010/12/09/the-chevrolet-volt-coolingheating-systems-explained/
Battery pack heating and cooling is independent of the engine.
As I've stated in other threads, winter driving is a major handicap of electric cars. When I try to run with electric cabin heating in my G2 volt, I have seen up to half of my power consumption go to heating. I get 1.X miles per kWh. Running an EV like this is not only expensive, it's horrible for the environment due to your long tail pipe. Let's just do a thought experiment and imagine that your local power station runs on gasoline (it doesn't, but it probably runs on either coal, natural gas, fission, or falling water. The average of all of these in the US is currently a bit better than gasoline). The power station is optimistically 50% efficient. Power transmission is 95% efficient. Car charging is 92% efficient. Let's just say that again, optimistically, 43% of the energy in that gasoline burned at the power plant gets to your drivetrain. This is about the same as an atkinson engine used in most modern hybrids. Driving around with electric heating most likely brings your effective gas mileage down into the 20's, and if it's very cold you might as well be driving around in a pickup truck or a suburban, because in order to heat your car with fuel burned remotely, you are losing over 60% of the energy content in that fuel.
There is another, much better way to heat a plug in hybrid car however, and it's called cogeneration. Cogeneration is when you burn fuel in order to produce mechanical work (or electricity) and then use the waste heat from that process for climate control. This makes a remarkable increase in the thermal efficiency of your engine. In europe, you can even get cogeneration units to heat your house; there is a small generator powered by oil or natural gas in your basement, and the coolant for that generator then heats your house. It makes a lot more sense than making electricity at the power plant because that other 60% of power that would normally be wasted is being put to use. While essentially all ICE cars use cogeneration for heating, they still expel most heat directly into the atmosphere because the heating requirements of an automobile cabin are several times lower than the amount of heat generated by an ICE to keep the car moving. The Volt doesn't work this way however... it only runs the engine long enough to heat your car, never opening it's thermostat to allow hot water to flow to the radiator. While it runs, it also recharges your battery, which means that you are effectively getting twice the bang for the buck compared to running in the summer.
If electric space heating was sensible and economical than most buildings would be heated this way. Boilers and furnaces are expensive to purchase, very expensive to install, noisy, space consuming, and require annual maintenance, but even despite all of those major disadvantages they are used for the vast majority of space heating in every part of the world. There is a reason GM chose to heat the car by running the engine and it's a very good reason. It is less expensive for the user of the vehicle and it is better for the environment. Unless your electricity is extraordinarily cheap as in QC Canada, you should never ever want to heat your car with battery stored electricity.
As an aside, I have been looking for a way to fool the car into thinking it's a bit colder so that I can engage ERDTT at a higher temperature. I usually want the heat on if it is less than 40f out, so I generally drive around in hold mode in this temperature range, again because it is less expensive to do so and because it's better for the environment.
There is another, much better way to heat a plug in hybrid car however, and it's called cogeneration. Cogeneration is when you burn fuel in order to produce mechanical work (or electricity) and then use the waste heat from that process for climate control. This makes a remarkable increase in the thermal efficiency of your engine. In europe, you can even get cogeneration units to heat your house; there is a small generator powered by oil or natural gas in your basement, and the coolant for that generator then heats your house. It makes a lot more sense than making electricity at the power plant because that other 60% of power that would normally be wasted is being put to use. While essentially all ICE cars use cogeneration for heating, they still expel most heat directly into the atmosphere because the heating requirements of an automobile cabin are several times lower than the amount of heat generated by an ICE to keep the car moving. The Volt doesn't work this way however... it only runs the engine long enough to heat your car, never opening it's thermostat to allow hot water to flow to the radiator. While it runs, it also recharges your battery, which means that you are effectively getting twice the bang for the buck compared to running in the summer.
If electric space heating was sensible and economical than most buildings would be heated this way. Boilers and furnaces are expensive to purchase, very expensive to install, noisy, space consuming, and require annual maintenance, but even despite all of those major disadvantages they are used for the vast majority of space heating in every part of the world. There is a reason GM chose to heat the car by running the engine and it's a very good reason. It is less expensive for the user of the vehicle and it is better for the environment. Unless your electricity is extraordinarily cheap as in QC Canada, you should never ever want to heat your car with battery stored electricity.
As an aside, I have been looking for a way to fool the car into thinking it's a bit colder so that I can engage ERDTT at a higher temperature. I usually want the heat on if it is less than 40f out, so I generally drive around in hold mode in this temperature range, again because it is less expensive to do so and because it's better for the environment.
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2,298 Posts
Absolutely not. The Battery Pack has its own internal heater independent and separate from the cabin electric heater.
Also, it is a fairly simple mod to perma-defeat ERDTT with the addition of a 25cent resistor like I performed on my Gen1 many winters ago!
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When ERDTT is running you are not generating any electricity. It is running just to produce heat. That is why many people want to defeat the ERDTT option. You are the first to want to go the other way. However, If you want to do it the way you explained in your post, you would want to defeat the ERDTT and run HOLD mode every chance you got. In that way you would be getting the advantage of heat and electricity production.
That's a bit surprising...it doesn't generate any energy during ERDTT? In my Highlander Hybrid it would draw from MG1 to charge the battery a bit any time the ICE was on, even if the vehicle was stopped and just warming up the engine for cabin temperature. It's usually not good to freewheel an electric motor with zero current flowing to/from it; it would surprise me if they didn't draw at least a little bit to charge the battery.
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