ERDTT worse MPG than Hold/Hybrid
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How do you measure MPG during ERDTT? The ICE provides about 6 kw and the rest of your power is coming from the battery. During ERDTT, most of the ICE heat goes into the cabin. In hold mode, some ICE heat may go into the radiator.
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ERDTT does show up as gas used and gas miles on the display
What the op will find is gas used on a longer trip ERDTT VRS hold is different than he expects.
What the op will find is gas used on a longer trip ERDTT VRS hold is different than he expects.
If you'll use the range, just switch to hold and it'll behave like hold. ERDTT gets lower numbers because it only runs the engine cold - when the engine is almost warm it turns off until it cools down again. This minimizes total gas used while driving basically electrically and receiving heat from the ICE, but it won't show good mileage numbers.
ERDTT makes sense for cases where you need the extra heat or would run out of electric range without it, but when using it you have enough range to complete the trip mostly electric.
For shorter trips, living with electric heat is better - no gas used. For longer trips, you're better off warning the car in Hold mode early in the trip.
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Go here and read post #8 for some real world numbers.
http://gm-volt.com/forum/showthread.php?218081-quot-Just-Driving-quot-my-2013-Volt-in-Cold-Weather
The short and sweet is that if you know the car is going to ERDTT, then you are better off manually forcing it to run long enough to get good and warm (and efficient) at the start of your drive.
http://gm-volt.com/forum/showthread.php?218081-quot-Just-Driving-quot-my-2013-Volt-in-Cold-Weather
The short and sweet is that if you know the car is going to ERDTT, then you are better off manually forcing it to run long enough to get good and warm (and efficient) at the start of your drive.
Yes. The mpg is atrocious. But ERDTT runs periodically only. Your average MPG for the hole trip, EV and ICE will be pretty good. In hold mode, your engine will run through your whole drive, which may consume more gas if you are driving below teh EV range.
You can try cycling back and forth from Hold to regular mode. But remember ERDTT will engae as soon as your coolant temp drops below 50c. Good luck.
You can try cycling back and forth from Hold to regular mode. But remember ERDTT will engae as soon as your coolant temp drops below 50c. Good luck.
Exactly this. I've got a good sampling because I've got a '12 and thus there is no hold mode, nor can ERDTT be adjusted. And over longer trips, overall fuel economy for ERDTT-"enabled" trips vary by temperature, but at temps close to the ERDTT threshold I get about 60-65 MPG overall for 25 mile trips, dipping down to 50ish at 0F. That's still substantially better than hold/CS would be at the same temps. The MPGcs looks terrible (12-15 MPG) at low city speeds for the distance driven while the engine's scrambling up to temperature, but that it runs intermittently salvages it overall.
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In our 2013, with ERDTT at 15F, I've noted that on a longer trip you'll see the mpg from ERDTT improve through the journey as the engine temperature is higher.
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If only you could have full control over ERDTT (including disabling it near the end of your trip so the ICE doesn't kick in when you're almost there). Hint, you can. See my post here http://gm-volt.com/forum/showthread.php?279153-Hack-achieved!-ERDTT-is-now-ERDTD-(Engine-Running-Due-To-Driver)
Even my 2010 Prius when its cold below 30 degrees F while driving to work, car is parked outside, sometimes I can not even get 40 mpg for the 11.5 mile trip which is mostly flat with little or no elevation changes from sea level to work. The same trip in summer 55 mpg is the norm. Cold is a big factor in mpg.
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I have a 38 mile round trip every day. Once the temperature is below freezing, unless I'm in the mood for an entirely unheated drive, I'll need to burn some gasoline.
My overriding rule is to try to keep to one warm-up cycle per day. I figure close to .1 gallon is being used just to get the engine block and plumbing warm enough to be useful for heat and there's no point paying that toll twice in the day.
If the morning temperature is below 15 F then I'm committed to burning gasoline anyhow, so I take steps to ensure that my return trip can be purely electric.
About the last 1/3 of my morning drive is freeway, so I kick in Hold until I'm within 3 or 4 miles of work, then use the residual heat to get there.
Why add Hold to ERDTT? Because if the day stays below 45 degrees my return trip is going to take more out of the battery (an extra 1.5 kW for the first 15 minutes) to bring the battery up to temperature after cold soaking at work all day (I can't plug in there).
Assuming no ERDTT in the morning, I just use whatever electric heat I need and leave the engine off until the afternoon drive.
For that cold afternoon drive, I have experimented with switching the ERDTT setting to cold to get my heat and range but have concluded that I'm better off kicking in Hold mode for the first part of that drive to get me the heat and battery for my return.
We also have a 2011 Prius and what you say above is absolutely correct, as it is for any ICE-driven car.
The big benefit of driving a post-2012 Volt is that I can manipulate things to reduce the number of warm-up cycles in a day.
My overriding rule is to try to keep to one warm-up cycle per day. I figure close to .1 gallon is being used just to get the engine block and plumbing warm enough to be useful for heat and there's no point paying that toll twice in the day.
If the morning temperature is below 15 F then I'm committed to burning gasoline anyhow, so I take steps to ensure that my return trip can be purely electric.
About the last 1/3 of my morning drive is freeway, so I kick in Hold until I'm within 3 or 4 miles of work, then use the residual heat to get there.
Why add Hold to ERDTT? Because if the day stays below 45 degrees my return trip is going to take more out of the battery (an extra 1.5 kW for the first 15 minutes) to bring the battery up to temperature after cold soaking at work all day (I can't plug in there).
Assuming no ERDTT in the morning, I just use whatever electric heat I need and leave the engine off until the afternoon drive.
For that cold afternoon drive, I have experimented with switching the ERDTT setting to cold to get my heat and range but have concluded that I'm better off kicking in Hold mode for the first part of that drive to get me the heat and battery for my return.
We also have a 2011 Prius and what you say above is absolutely correct, as it is for any ICE-driven car.
The big benefit of driving a post-2012 Volt is that I can manipulate things to reduce the number of warm-up cycles in a day.
The gen 2 actually shows how much fuel is consumed in ERDTT. The first ERDTT run actually dumps .38L of fuel in to the engine and lights on fire just get the temp up to 60. After that it kicks back in everytime the coolant drops below 50 and cyles off at 60. The subsequent runs burn about .25L.
At highway speeds you essentially run half gas and half EV miles. Yes it's annoying when a cyce runs just before you park the car. But look at it this way, you are progressing down the road to your next fuel mainenance mode. If you fill up in spring, you can hold the same tank until next winter.
At highway speeds you essentially run half gas and half EV miles. Yes it's annoying when a cyce runs just before you park the car. But look at it this way, you are progressing down the road to your next fuel mainenance mode. If you fill up in spring, you can hold the same tank until next winter.
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ERDTT dumps around 60% of the gas' calorific energy into cabin heat, 30% out of the exhaust and a dribble of 10% electrical energy into the battery.
Hold dumps around 35% of the gas' calorific energy into cabin heat, 30% out of the exhaust and 35% electrical energy into the battery.
These figures are, of course, just ball-park, it will vary depending on how you actually drive/use the car. They also assume the transmission hasn't dropped into power-split.
However, it should be obvious from these why the car's mpg in the two modes is different.
Hold dumps around 35% of the gas' calorific energy into cabin heat, 30% out of the exhaust and 35% electrical energy into the battery.
These figures are, of course, just ball-park, it will vary depending on how you actually drive/use the car. They also assume the transmission hasn't dropped into power-split.
However, it should be obvious from these why the car's mpg in the two modes is different.
the main problem with ERDTT is that the car has no idea how far you are going to drive it.
if it knew, by having navigation integration smarts, it could determine the best course of action for the planned trip.
Then it could know when to run the ICE in the most efficient manner as per the destination routing and all the variables that affect efficiency.
if it knew, by having navigation integration smarts, it could determine the best course of action for the planned trip.
Then it could know when to run the ICE in the most efficient manner as per the destination routing and all the variables that affect efficiency.
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