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Discussion Starter · #1 ·


OnStar data is harvested from the monthly diagnostic emails. Average monthly temperature comes from The Capital Weather Gang of the Washington Post which posts the average monthly temperature for National Airport.

I only drive locally, rarely use climate control. So, any differences can be attributed just to temperature changes. I have gotten more efficient with my driving after year one. This can be attributed to three things.
1) raising the PSI eventually to 50 in my tires.
2) extensive use of neutral
3) becoming more obsessed with getting a "good grade" in the monthly emails :)
 

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Just asking for clarification by a non-VOLT driver. Is the kWh/miles based on the electricity from the wall, which includes inefficiency from the inverter pumps, etc? Or is it based on the energy in the traction battery?
 

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My last few monthly diagnostic emails have not included the kWh/100 miles. Just lists ---. Anyone else seeing this?
 

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Thanks for sharing, definitely about a 30% drop in cold weather. It has been warm here so I have been able to regularly get 4.2 kW/mi or better now that the temperature is up, but in the winter it is sometimes less than 2 (heavy heater usage and average temp around 22 F in winter). I think those correspond to 23 to 50 range.

I am curious to see how Volt 2 does with similar temperature drop; see if the chemistry is any better in the cold.
 

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Discussion Starter · #5 ·
My last few monthly diagnostic emails have not included the kWh/100 miles. Just lists ---. Anyone else seeing this?
Dennis mine disappeared from November through April. This last one was the first one to have the kWh / 100 miles again. I just went to the myvolt website to get the figure.

Not sure how difficult it is to populate all the fields, but I guess that is too much to ask of OnStar!

Just asking for clarification by a non-VOLT driver. Is the kWh/miles based on the electricity from the wall, which includes inefficiency from the inverter pumps, etc? Or is it based on the energy in the traction battery?
I believe the OnStar figure of kWh/100 miles includes any charging losses.
 

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I am curious to see how Volt 2 does with similar temperature drop; see if the chemistry is any better in the cold.
There is very little a chemistry could do.
All cars loose about 20% efficiency just due to physics. It takes more energy to push a car through cold air than warm air.
Likewise there is more rolling resistance on roads with snow on them.
Most EVs loose about an extra 10%. With cars like the Volt, with a good battery management system, some additional energy is lost when heating the battery pack.
With those without, some more efficiency is lost due to the batteries operating at colder temps, but less energy is lost to heating the pack. Frankly, purely from an efficiency point of view, I am not sure if one is better than the other.
 

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There is very little a chemistry could do.
All cars loose about 20% efficiency just due to physics. It takes more energy to push a car through cold air than warm air
Please site a source for this 20% claim.

What you fail to mention is that ICEs run better in cooler denser air. If you have forced induction the changes are even more noticeable.
 

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Please site a source for this 20% claim.

What you fail to mention is that ICEs run better in cooler denser air. If you have forced induction the changes are even more noticeable.
What do you mean by "ICEs run better in cooler denser air", are you talking about the MPG? Also what do you mean by "forced induction" - turbocharged?
 

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OnStar data is harvested from the monthly diagnostic emails. Average monthly temperature comes from The Capital Weather Gang of the Washington Post which posts the average monthly temperature for National Airport.

I only drive locally, rarely use climate control. So, any differences can be attributed just to temperature changes. I have gotten more efficient with my driving after year one. This can be attributed to three things.
1) raising the PSI eventually to 50 in my tires.
2) extensive use of neutral
3) becoming more obsessed with getting a "good grade" in the monthly emails :)
Looks like the average summer temps have been getting cooler in North America 84-81-79 . I thought more Carbon Dioxide meant the ice melted and bears died .
 

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What you fail to mention is that ICEs run better in cooler denser air. If you have forced induction the changes are even more noticeable.
ICEs can make more power in dense air, but are generally more efficient in thin air.

Consider a 200 hp rated engine cruising down the street using 20 hp. The throttle plate is almost closed so pumping losses are very high. Go high enough so the thin air makes limits max output to 100 hp. That same 20 hp cruising condition has the throttle plate much more open ==> more efficient.
 

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Please site a source for this 20% claim.

What you fail to mention is that ICEs run better in cooler denser air. If you have forced induction the changes are even more noticeable.
I suppose part of it depends upon the definition of "cold".
In Georgia this should affect you much less than it does for those where it gets colder.
I've been tracking mpg, and then range by season for quite some time, although I stopped about a year or so ago.

I've also spoken with others who have done the same.
In MN, winter mpg is consistently 19-21% below summer mpg.
This holds steady by make, model, even vehicle type.

It isn't very noticeable when a Truck that gets 12mpg drops to 10. When you start at 40mpg and drop to 32 it is pretty apparent.

Here is a source for you: https://www.fueleconomy.gov/feg/coldweather.shtml
 

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Thanks. I was very skeptical of the 20% claim.

With the sports car...well MPG doesn't really matter. It is not the point of the car. I used to track it out of curiosity and it seemed fairly consistent. But I did not plot it or track it all that closely.

The Prius is my wife's car. I keep an eye on what kind of MPG I get but she introduces too many variables. Plus she does not drive in a manner that takes into account achieving good gas mileage.

The Volt is replacing the Prius. It will be interesting to see how it does battery range wise on her commute.

As for the question on Forced Induction. Yes, turbo or supercharged.
 

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Thanks. I was very skeptical of the 20% claim.

With the sports car...well MPG doesn't really matter. It is not the point of the car. I used to track it out of curiosity and it seemed fairly consistent. But I did not plot it or track it all that closely.
...
I understand, I was rather surprised myself when I first started paying attention.
Our former Prius averaged 52 mpg in the summer, and 42 mpg in the winter.
As long as it is the same drivers, the change should still be valid. If you drove in the summer and your wife in the winter, that would throw things off.

We replaced one of our Prii with a Volt as well. It was, for us, a great move, we enjoyed the Volt quite a bit.
 

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This is the data viewed a little differently

Red Dots are the data points from the first year
Green Dots are the remaining data points
Blue Bars are the average of the green dots for the temperature range covered.
Green Line is an Excel generated trendline of the green dots.


AriCData.jpg
 

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Discussion Starter · #15 ·
This is the data viewed a little differently

Red Dots are the data points from the first year
Green Dots are the remaining data points
Blue Bars are the average of the green dots for the temperature range covered.
Green Line is an Excel generated trendline of the green dots.
Very cool. Nicely done!
 
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