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Hello !
Can someone tell me the official gm reason for the ERDTT ? Fog in the dash, heat assistance for driver...?
 

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Federal regulations require that vehicles with and engine be able to clear the windshield in a given amount of time. Starting the engine makes this possible in the Volt. Those regulations do not apply to BEVs since they don't have an engine. Hence not an issue with a Tesla or a Bolt EV.
 

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I sometimes wonder about the true reason for ERDTT.

Granted, we live in a world of tradeoffs. Maybe, to meet the required levels of defrost at cold ambient temperatures would have required an even larger electric heater in the Volt, and that may have lead to increased cost and lower EPA efficiency ratings. On those cold days, the heater would have drawn so much power that the Volt would have reduced power output (the battery can only supply so much power). People would not be happy if they had less performance on cold days.

In addition, the battery pack performs best in a temperature window of about 35 F to 78 F, IIRC. As you get outside these temperatures, you must heat or cool the battery pack. This is yet another power draw that the Volt must contend with on cold days.

My personal belief is that the GM engineers weighed all the design parameters and came up with a good compromise. The Volt is an EV is most driving scenarios, but in extreme cold temperatures, they utilize the ICE to provide cabin heat and battery pack heat. Since you have an ICE anyway, this was the best way to solve the cold temperature issues.
 

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Either way GM would not win. If they did not have the ERDTT then people would complain that there was no faster way to heat the cabin. The thing they could have done is allowed us to turn it off and make our own choice.
 

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Either way GM would not win. If they did not have the ERDTT then people would complain that there was no faster way to heat the cabin. The thing they could have done is allowed us to turn it off and make our own choice.
They kind of did. There's a setting to reduce the ERDTT from 35F to 15F. I think it's called "deferred" somewhere under the vehicle settings (at least in the Gen 2).
 

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Either way GM would not win. If they did not have the ERDTT then people would complain that there was no faster way to heat the cabin. The thing they could have done is allowed us to turn it off and make our own choice.
Indeed. The only issue with ERDTT is that you can't override it in the car. On the 2 mile round trip to the grocery store on a cold day ERDTT doesn't do much anyway except burn gas and pollute the air.

In my opinion, they've set the lower limit to 15*F ready for a heat pump.
 

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I sometimes wonder about the true reason for ERDTT.
... My personal belief is that the GM engineers weighed all the design parameters and came up with a good compromise. The Volt is an EV is most driving scenarios, but in extreme cold temperatures, they utilize the ICE to provide cabin heat and battery pack heat. Since you have an ICE anyway, this was the best way to solve the cold temperature issues.
I modified this fall the temp sensor so that ERDTT doesn't start unless outside temp is about -35C. I never had a problem with the heat in my car, even though we had some very low temperatures, and yes, the car was outside unplugged for more than 7 hours.
I don't really buy the GM explanation about ERDTT, because I've never seen posted why they agreed to modify the temp from -4C to -10C (Gen1 2012 vs Gen 1 2013+ and Gen 2). Why -10 C was their choice, it is a mystery to me. -18 C (0F) would have been more suitable IMHO, and I am sure many of the owners would have not modify anything on their car.

And why we have ERDTT in the Volt when the same system is used in Bolt and Spark EV. Those don't have a problem with defrosting then ?
 

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Engineering decisions are not made by flipping a coin. There are always multiple solutions, with both good features and bad features.
 

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I just discovered this morning my ELR does it at 32.


I couldn't care less. The whole crying about burning gas once in a while is crazy...Go buy a Leaf.
 

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I just discovered this morning my ELR does it at 32.


I couldn't care less. The whole crying about burning gas once in a while is crazy...Go buy a Leaf.
Unless you do a 2 miles commute every day during winter. Which is a pain from ICE point of view, because in 2 miles it doesn't warm up and it gives you about 15 mpg or less in cold weather. But you have 23-24 miles AER at your finger that you can't use. Pretty smart engineering... NOT !
 

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Unless you do a 2 miles commute every day during winter. Which is a pain from ICE point of view, because in 2 miles it doesn't warm up and it gives you about 13 mpg or less in cold weather.
So what? you mean like a regular car? It behaves like a regular car once in a while? The horror!
 

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The horror is I have 23-25 miles AER at my disposal I can't use ! Hmm, is this smart engineering for you ?
So what? How often does it happen? Is it really enough to matter? Doubt it!
 

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So what? How often does it happen? Is it really enough to matter? Doubt it!
Lets say it happens about 40 days during winter if we are talking about ERDTT only. So... why should one pay for the gas a cent when the car itself can do it all on EV mode ? Usually January and February are the worst here and some days in December.
 

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Lets say it happens about 40 days during winter if we are talking about ERDTT only. So... why should one pay for the gas a cent when the car itself can do it all on EV mode ? Usually January and February are the worst here and some days in December.
Buy a leaf. Then you never have to pay for gas. Ever. Or, one can deal with the limitations of design and legal requirements.
 

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Buy a leaf...
Is this your "Trump answer" or what ? Sorry to say it like this, but your advice about the Leaf is not an option because I would need a second car for vacations or week-ends. This is the reason I bought the Volt in the first place: an EV during work days and a hybrid during week-ends.
 

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Is this your "Trump answer" or what ? Sorry to say it like this, but your advice about the Leaf is not an option because I would need a second car for vacations or week

You miseed the rest of my "President Trump Answer"... Let me repost -


"Or, one can deal with the limitations of design and legal requirements."

Our President works in the way the world is, not how he wishes.... So, yes, that is my Trumptastic answer.
 

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I only made a distinction between you first part - Trump like - and the rest, which are more like you. And no, Trump is not as the world is. World, as far as I know, when in doubt, reads and informs itself. When mistaken, it assumes it and try to correct it. NOTHING of these I see in Trump. He knows-it-all and he is always right.
 

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Trumps current 'car' is a Kodiak Diesel medium duty truck with a fully armored Cadillac body attached, it is about 13,000lb. It flies more miles than it is driven and gets about 5 mpg. He inherited it from the last POTUS.

Not sure if it has ERDTT, but diesels hate the cold. The fuel jells and you are stuck.
 
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