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Discussion Starter #1
Assuming the temp remains 25F or less (2012 Volt). From the first time it goes on to the second time on the same trip, is it based on distance or time?

Thanks,
MrEnergyCzar
 

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Neither, it is based on the coolant temperature. I guess the colder it is the quicker the temperature would drop. Here is the best description I could find on how it works.

See page 4 here: http://www.sandyblogs.com/techlink/Jan 2011 Techlink F.pdf

"At ambient temperatures of approximately 25° F (–4° C) or below, the ICE will operate to assist in warming the coolant used to warm the vehicle’s cabin. After the coolant temperature reaches approximately 150° F (65° C), the ICE will turn off and remain off (as long as the battery state of charge is sufficient) until the engine coolant temperature drops to approximately 104° F (40° C), at which time the ICE will restart. This function will continue as long as the ambient temperature is approximately 25° F (–4° C) or less while driving. After the ambient temperature rises above approximately 25° F (–4° C), the vehicle will resume normal electric operation (as long as the battery state of charge is sufficient). This is normal operation and no repairs should be made to correct this condition."
 

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I think neither but rather based on temperature instead. I think when the interior air temp drops below the set temp the ERDTT will kick in instead of the electric heater or in conjunction with the electric heater.
 

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Actually, neither. First run is based on outside temperature. Subsequent runs are based on coolant temperature. That will cool off faster if you're driving faster, using heat on Fan only, or it's colder out.

MrEnergyCzar: The best way to minimize ERDTLT run times on 2011-2012 Volts is to put the Climate to Comfort and throttle the fan back one or two settings from the default Auto speed. Comfort and Eco (on the 2011-2012) let the resistive heating element kick in still in between ERDTLT engine run cycles. With Comfort and this slightly lower setting, the resistive heater can often maintain the coolant temperature necessary to prevent subsequent ERDTLT cycles, while still keeping you warm.

See my recent post where I just talked about this and how the 2013-2014 behaves as well...
http://gm-volt.com/forum/showthread.php?88778-ERDTLT-Differences-Between-Model-Years

EDIT: Yikes, we all responded to that one at the same time guys! ;)
 

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I am pretty sure it is coolant temp If it cools below 25 it will start. It will start more often the colder it is.
 

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From what I can tell with my MY2013 volt, the outside temperature and the speed of the car, the faster you drive the faster is cools. I have also found that you get better gas mileage at a higher speed since the engine runs at a constant RPM and if you drive faster you get a high MPG. But that cools the coolant faster which cause the engine to run. When the temps are around 0 or below ERDTT runs for miles off for a mile then on again. I wish it would have another setting for Stupid Cold Temps like down to Zero, if I could set it for that I would not complain when it the temps were negative and I got ERDTT. Well off to take my son's friends home, and more ERDTT, since it is below 15 degs outside.
 

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I wish it would have another setting for Stupid Cold Temps like down to Zero, if I could set it for that I would not complain when it the temps were negative and I got ERDTT. Well off to take my son's friends home, and more ERDTT, since it is below 15 degs outside.
If you change your console display to Metric units, it will be negative temps on the "Very Cold" setting! ;)
 

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It's been stupid cold here in MN with -16F yesterday morning. Since the ERDTT is going to run the ICE anyway I put it Mountain mode just to see what it did. Obviously we don't have any mountains here in MN to speak of. I think it did a better job of keeping the cabin warm and saving gas than running in Normal mode at the same temperature. At times the ICE would be running but at very low RPM - enough to keep the coolant temp above threshold - while propulsion was primarily electric. Occasionally the ICE would should off but I never went more than two miles before it came back on. The temperature finally climbed to +18F and I drove electric all the way home for a daily mpg of 72 over 53 miles with 34 of it at -5F this morning. I'm satisfied with that. When I got home my Kill-a-Watt meter had arrived so I'll get to see tomorrow morning what a full charge at this temperature is going to cost me.
 

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It's been stupid cold here in MN with -16F yesterday morning. Since the ERDTT is going to run the ICE anyway I put it Mountain mode just to see what it did. Obviously we don't have any mountains here in MN to speak of. I think it did a better job of keeping the cabin warm and saving gas than running in Normal mode at the same temperature.
Nice. Remember though, if your commute is short enough to do with battery only, running in MM will only use more gas than ERDTLT.
 

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Nice. Remember though, if your commute is short enough to do with battery only, running in MM will only use more gas than ERDTLT.
My commute is 18.5 miles each way with no charging available in between. It's not a flat 18.5 miles either so I have found that I can maximize the range by kicking in the ICE on the significant uphill climbs. Until it got stupid cold I was using about .3 gallons per day for 45 miles when the temperature was in the positive teens - something that feels positively balmy after a week of negative teens.
 

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My commute is 18.5 miles each way with no charging available in between. It's not a flat 18.5 miles either so I have found that I can maximize the range by kicking in the ICE on the significant uphill climbs. Until it got stupid cold I was using about .3 gallons per day for 45 miles when the temperature was in the positive teens - something that feels positively balmy after a week of negative teens.
My commute is almost the same distance 38 miles r/t. While there are charging stations on the route, I try not to use them unless I have to.

I installed a modified sensor on Monday and was able to make the commute in using 4.2 kWh when it was 22F. Since I had more than plenty to spare for the return trip, I did not drive as efficiently. Of course I am going without any heat so it is a little cold.

I have this game going to see how far and long I can go without engaging my ICE (except for Maintenance modes). So far, I am up to 31,500 miles over a period of 1.5 years (568 days) and counting!
 

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Discussion Starter #15
Actually, neither. First run is based on outside temperature. Subsequent runs are based on coolant temperature. That will cool off faster if you're driving faster, using heat on Fan only, or it's colder out.

MrEnergyCzar: The best way to minimize ERDTLT run times on 2011-2012 Volts is to put the Climate to Comfort and throttle the fan back one or two settings from the default Auto speed. Comfort and Eco (on the 2011-2012) let the resistive heating element kick in still in between ERDTLT engine run cycles. With Comfort and this slightly lower setting, the resistive heater can often maintain the coolant temperature necessary to prevent subsequent ERDTLT cycles, while still keeping you warm.

See my recent post where I just talked about this and how the 2013-2014 behaves as well...
http://gm-volt.com/forum/showthread.php?88778-ERDTLT-Differences-Between-Model-Years

EDIT: Yikes, we all responded to that one at the same time guys! ;)
It went on about 10 times today, used a gallon. I drove in Fan only when using battery and put it in comfort when the engine was running and switched back to fan only when the engine went off... set only at 72F. you're basically saying leave it in comfort throughout?

Thanks,
MrEnergyCzar
 

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Discussion Starter #16
Thanks! That's pretty cool document.
Wow, that link explains it. And I thought it was air temp mostly. I assume you can precondition while plugged in and that would raise the coolant temp? Eco or Comfort at 72F? Anyone actually do that?

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MrEnergyCzar
 

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Wow, that link explains it. And I thought it was air temp mostly. I assume you can precondition while plugged in and that would raise the coolant temp? Eco or Comfort at 72F? Anyone actually do that?
From what I understand that won't work. The first time the Volt detects 25F temps or whatever it is set to for 2013/14 models, ERDTT will run. I remember reading another member here who had his Volt in a warm garage and the engine would start almost immediately when leaving. Running heat will definitely help for subsequent ERDTT cycles.
 

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Wow, that link explains it. And I thought it was air temp mostly. I assume you can precondition while plugged in and that would raise the coolant temp? Eco or Comfort at 72F? Anyone actually do that?

Thanks
MrEnergyCzar
It doesn't work - we did some experiments last year. The Volt doesn't connect the engine coolant to the heater core until the engine is up to 150F or so - so preheating has no effect on whether ERDTT happens (the isolation isn't perfect, so it actually picks up a couple degrees, but not enough to matter.)
 

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I'm still confused on what HVAC settings to use during ERDTT. I have my car set to the upper limit (35 degrees) and right now I know that will cause the ICE to do its thing on my 11 mile trip to work. I set my HVAC to FAN and jack up the temps to HI and leave it there.

Why would setting the HVAC to COMFORT be better?
 

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I experienced one (and only one) ERDTT this morning, seconds after backing out of my garage. I immediately placed the HVAC into Comfort, HI, & Max. Fan speed. The engine ran its customary ~1.5 miles/0.3 gal. and then the Volt switched back to CD mode. I kept the HVAC in Comfort, Hi, and then lowered the fan speed to 2. I watched the coolant temp over the course of my entire commute (34 miles), through my Torque app and the coolant temp never got lower than 138*F. The outside air temperature was always below the 25*F threshold. I was able to get 29 eMiles before the engine came on for the remaining 5 miles...I used 1/4 gallon of gas.
 
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