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Discussion Starter #1
Hi,

So last weekend I did a road trip in which I would use some gas. I tried out Hold Mode and it worked almost exactly as advertised. The one weird thing that it did was when I turned off hold mode and switched back to the battery, the energy screen kept reporting the milage as gas miles. I wasn't sure exactly how many so I decided to run an experiment.

So today I went on another trip that would use gas. I turned on hold mode and drove for exactly 21 miles on gas. When I switched back to electric, it recorded 2.5 more miles as gas (total gas miles was 23.5) before continuing to record as electric.

Why is it doing this? Is this normal behavior?
 

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I think so. people with the gen1 Volt also report this. It knows you went up a grade and credits you with the downhill slope.
 

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I turned on hold mode and drove for exactly 21 miles on gas. When I switched back to electric, it recorded 2.5 more miles as gas (total gas miles was 23.5) before continuing to record as electric.
Why is it doing this? Is this normal behavior?
Here's the short version:
When the car's burning gas, it's usually producing a little more energy than the engine needs, so it has some extra oomph for acceleration.
The car keeps track of how much juice in the battery came from the charger, how much from regen, and how much from the engine. So when you shut off hold, there was some extra juice in that battery that came from gasoline. So it 'runs off' that gas-generated power before it starts counting electric miles.

It's normal. The Volt is one of the best engineered, most intelligent, advanced vehicles on the planet.
Piece of advice, don't try to outsmart it.
The only time you can do better than the computer is when it's cold, you know you're going to drive farther than the battery can take you, and you can use hold to heat the car off the gas engine heat. But that's only because the car can't know how far you're driving.
 

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I've noticed that too, but after year one of Volt ownership, I don't pay any attention to much of anything anymore. Switched the heat to Comfort, leave it at 74°, and use hold on trips. The car's so smart it's pretty hard to best it's brain, and my lifetime mileage is still over 83 mpg. Love my Volt!
 

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I've seen this on my Gen 1. I figured it "knew" it was still consuming the electricity produced by the range extender.
 

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Hi,

So last weekend I did a road trip in which I would use some gas. I tried out Hold Mode and it worked almost exactly as advertised. The one weird thing that it did was when I turned off hold mode and switched back to the battery, the energy screen kept reporting the milage as gas miles. I wasn't sure exactly how many so I decided to run an experiment.

So today I went on another trip that would use gas. I turned on hold mode and drove for exactly 21 miles on gas. When I switched back to electric, it recorded 2.5 more miles as gas (total gas miles was 23.5) before continuing to record as electric.

Why is it doing this? Is this normal behavior?
When in hold mode, sometimes excess energy is generated, for example, if you drive slightly up hill on gasoline and then switch out of hold mode on the down slope the car will count the down hill miles as gasoline miles since the regenerative braking is actually taking your state of charge higher than what it was when you switched into hold mode. All miles until you reach that same SOC you were at when you switched into hold mode will be counted as gas miles since the energy used is presumed to have been generated by using gasoline rather than coming from the grid.

Keith
 

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Discussion Starter #7
Thanks Everyone,

I suspected as much, but I searched around on the forum and couldn't find any mention of this. This makes sense now.

I never had hold mode on my 2012 Volt, but I did have Mountain Mode. I used it when I knew I would be on a freeway going 65+mph, as I found that the gas engine is more efficient at higher speeds. When I would switch back to Normal from Mountain Mode it would immediately switch back to battery and start counting the milage as electric.
 

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Correct, the car is counting where the electricity it is using came from: the wall or the ICE. So any extra electricity produced by the ICE under hold and stored in the battery is counted as gas miles until it's used up.

Extreme example, you put the car in Hold with 2 electric miles left and run the car on gas long enough to add 5 extra electric miles to the battery though the ICE and regen. When you exit Hold, the battery shows 7 miles in the battery but will be recording miles as gas miles until you are down to 2 miles. At that point it will switch to counting electric miles again.
 

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I never had hold mode on my 2012 Volt, but I did have Mountain Mode. I used it when I knew I would be on a freeway going 65+mph, as I found that the gas engine is more efficient at higher speeds. When I would switch back to Normal from Mountain Mode it would immediately switch back to battery and start counting the milage as electric.
What the car is doing is tracking your AER performance. Everything else is "other than Electric Miles and kWh Used."

Let me recap your 2012 Volt experience: you switched to Mountain Mode to preserve some battery power for the end of the trip, you switched back to Normal Mode, the ICE shut off and the electric miles immediately started increasing again.

What you might not have noticed is that the kWh Used number did not start increasing again until you drove some distance down the road (i.e., not until the battery soc had dropped to where it was when you switched to MM).

The 2011/2012 Volts had a programming glitch that resulted in the counting of MM-recharged battery miles as electric miles if you switched to MM before the battery was fully depleted, allowed the system to recharge your battery, then switched back to Normal mode.

The Volt is an electric car. Before the inclusion of Hold mode, you would drive using grid power stored in the battery. As you drove on grid power, regen would now and then put some power back into the battery (the kWh Used number can be observed decreasing during long downhill regen). When the battery was fully depleted, your kWh Used number would represent the net grid power consumption, and the Electric Miles your AER.

Once the battery was fully depleted, gas-generated electricity replaced grid electricity as fuel. Regen continued to put power back into the battery. Distances driven beyond the AER were recorded as Gas Miles. Net gas-generated kWh Used was not tracked. This makes it impossible to compare AER electric mileage with Gas Miles gas-generated electric mileage. Separate City/Hwy miles/kWh mileage ratings for various electric cars might well prove interesting!

Hold mode threw a monkey wrench into this accounting system. Hold mode is engaged before grid power is used up. If the battery’s charge is increased while in Hold or MM mode (because of regen or other factors), the use of that increase in the charge can’t be included in the tracking of the grid electricity for your AER stats, so it must be recorded as Gas Miles, even though you’re driving on battery power. Note your kWh Used number when switching to Hold or Mountain Mode. After switching back to Normal mode, if you see Gas Miles are increasing because you are driving on battery power that was added after engaging Hold or MM, that kWh Used number should not increase. Once the Electric Miles are again increasing, the kWh Used number will, too.
 
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