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Long description short: ICE (HOLD) is switched to SPORT but Gas odometer keeps ticking away. The car doesn’t release to battery usage. Has also happened on a 100+ mile return trip on hilly interstates, MOUNTAIN charges to 11 or 12 miles and shuts off. I switch to SPORT/NORMAL yet Gas odometer continues to tick away. Has anyone experienced this or wants to try and duplicate it for GM?

Happens every morning going up 495 to the Lincoln Tunnel. Bottom of the hill I switch to HOLD, traffic is moving at the posted speed limit or a little better. At the crest of the hill, back to SPORT (I can gain 4-6 mpg battery) by the time I am in Manhattan. But the 1.4 mile going up the hill has registered as 3 miles of gas used and is still ticking away. It has gotten difficult to return to normal operation, for a while I would go back through the process of HOLD to SPORT but now it is stuck in Gas as fuel even as the battery guess of meter ticks down.
 

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I believe when you use Mountain mode, those EV miles are credited to the engine, not the battery. That's because the engine (gas) created those miles, not electricity from the plug in your house. What you will find is that as you use those Mountain Mode generated miles, your ICE mpg will increase (usually back to what it was before you asked it to do extra work putting juice back in the battery).
 

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The Volt travels a lot of battery powered miles that are correctly registered as gas miles, because the purpose of the energy usage screen is show you how many "electric miles" you drive using the grid power you’ve pulled from the wall when recharging (and any regen you get and use while driving on grid power). A lot of your Extended Range Mode Gas miles are recorded while your Volt is propelled by the motor using battery power.

Consider this: when you drive downhill in any mode, you may get some downhill regen. If you drove downhill in Hold mode, at the bottom of the hill, you’ll drive regen-powered battery miles that count as Gas miles. If you drove downhill in Electric Mode, at the bottom of the hill you’ll drive the same number of regen-powered battery miles that count as Electric miles.

If you drive your Gen 2 Volt until your battery level is below ~2 bars and then switch to Mountain Mode, MM will recharge the battery back up to the MM-maintained level, ~2 bars. When you drive battery-powered distances using that MM-recharged battery power, it counts as Gas miles because you used gas to create that battery power.

If you drive until your battery level is at 1 bar of power and then switch to MM, MM will recharge the battery back up to the MM-maintained level, ~2 bars. If you then switch to Normal, you’ll drive using MM-recharged battery power, recording the battery-powered distance as Gas Miles, until you’ve used up the 1 bar of MM-recharged power. Then you start using the remaining 1 bar of grid battery power, and the battery-powered distances will now be recorded as Electric Miles until you fully deplete the battery.

When driving in Hold, normal operations use the battery as a buffer, and the battery state of charge cycles below and above the state of charge where you switched to Hold mode (which is also the level of grid power remaining in the battery).

When driving uphill in Hold mode, the motor may draw power from the battery and drop the state of charge below the Hold point. The generator then starts up and brings the charge back up to the Hold point, and perhaps a bit over. If that happens to be the moment at which you crest the hill and start down again, and that’s the moment you pick to switch back to Normal mode, your battery state of charge will remain above the Hold point all the way down the hill, and may even increase when downhill regen puts more charge back into the battery.

As far as the "accounting system" is concerned, as long as the battery state of charge is above the grid power level (i.e., the previously set Hold point), the battery-powered driving you do using any power in the battery above the grid power level is to be recorded as Gas miles.... and that would include the downhill distance and the distance you drove using the downhill regen...

Once the battery state of charge has dropped to the grid power level (i.e., the point when you shifted into Hold), the battery powered driving distances switch from Gas to Electric miles.

It would seem wise to shift from Hold to Normal mode a bit prior to cresting the hill to be sure the battery state of charge is not above the previously-set Hold level when you start down the hill (a visual confirmation would be to observe your electric miles start increasing as you drive down the hill)...
 

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The Volt travels a lot of battery powered miles that are correctly registered as gas miles, because the purpose of the energy usage screen is show you how many "electric miles" you drive using the grid power you’ve pulled from the wall when recharging (and any regen you get and use while driving on grid power). A lot of your Extended Range Mode Gas miles are recorded while your Volt is propelled by the motor using battery power.

When driving in Hold, normal operations use the battery as a buffer, and the battery state of charge cycles below and above the state of charge where you switched to Hold mode (which is also the level of grid power remaining in the battery).


As far as the "accounting system" is concerned, as long as the battery state of charge is above the grid power level (i.e., the previously set Hold point), the battery-powered driving you do using any power in the battery above the grid power level is to be recorded as Gas miles.... and that would include the downhill distance and the distance you drove using the downhill regen...

Once the battery state of charge has dropped to the grid power level (i.e., the point when you shifted into Hold), the battery powered driving distances switch from Gas to Electric miles.

It would seem wise to shift from Hold to Normal mode a bit prior to cresting the hill to be sure the battery state of charge is not above the previously-set Hold level when you start down the hill (a visual confirmation would be to observe your electric miles start increasing as you drive down the hill)...
I didn’t include that the Headlights must be ON for the oddity to occur.

Thank you for your detailed explanation, are you a GM employee?
Going up the hill under Hold/ICE usage is 1.5 miles, going down is 2 miles in Sport, wouldn't that record .5 miles as regen electric? The dash shows +4-5 usually and the center screen shows all the miles as ICE miles, and would have kept going if I hadn't turned the car off and back on. MPG goes up to 79. Could this be the way GM has such high MPG ratings?

I have observed a few other oddities, like it happens the other way around too, Ice on but not ticking away miles, much more than a a tenth of a mile credited to electric, miles.
So why in HOLD, on the dash the battery power side shows usage that is not shown on the center screen, it all goes to gas. The hold point in ICE mode moves down more often than up and is not "accounted" to electric
 

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I always presumed it just kept a rolling tally. That is, if I put it in Hold mode and use 2 kWH in Hold mode and then switch to Sport/Normal, it's going to count the next 2 kWH used on battery as gas usage because those 2 kWH were basically "generated" by gas.

But now that I actually think about it, that's double counting. It already counted that 2 kWH as gas because the gas usage was going up while I was driving. So the 2 kWH remaining in the battery (that it DIDN'T) use, are just in the bank from the grid.

So I guess mountain mode is the only mode that has to keep a tally because mountain mode is the only mode where gas actually charges UP the battery.

Mike
 

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I didn’t include that the Headlights must be ON for the oddity to occur.

Thank you for your detailed explanation, are you a GM employee?
Going up the hill under Hold/ICE usage is 1.5 miles, going down is 2 miles in Sport, wouldn't that record .5 miles as regen electric?
Only if it took as much energy to go down the hill as up. The accounting works on kwh, not miles.
 

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I'm a software engineer just like Dilbert. Just like in the Dilbert comic strip, the marketing types ask me to add features to our product.

Me: I don't really have enough data in the system to give the customer accurate displays.
Marketing: Accuracy doesn't matter, it's just to entertain the customer.
Me: Mark my words, some customers will notice the discrepancies and make my life miserable.
Marketing: We don't care, just implement it.
 

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So if I have a Gen 2 Volt. and operating in Hold Mode with a partially discharged battery say 50% charge I do this.
I climb a 4,000 foot mountain in hold mode (gas only),and at the top of the mountain I place the Volt in Electric mode. Now going down 4,000 or so feet I generate quite a bit of electricity, say 3-4 KWH.

Now down the bottom of the mountain I stop at the rest area, and shut the Volt off. Come back a few minutes later and start the Volt which automatically goes to electric mode. Now with those 3-4 KWH extra in the battery when I'm driving will the car record those miles as electric or gas miles because those 3-4 KWH were only placed there by the gas engine, and not by a plug.
 

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So if I have a Gen 2 Volt. and operating in Hold Mode with a partially discharged battery say 50% charge I do this.
I climb a 4,000 foot mountain in hold mode (gas only),and at the top of the mountain I place the Volt in Electric mode. Now going down 4,000 or so feet I generate quite a bit of electricity, say 3-4 KWH.

Now down the bottom of the mountain I stop at the rest area, and shut the Volt off. Come back a few minutes later and start the Volt which automatically goes to electric mode. Now with those 3-4 KWH extra in the battery when I'm driving will the car record those miles as electric or gas miles because those 3-4 KWH were only placed there by the gas engine, and not by a plug.
Those 3-4 kWh were not placed there by the gas engine. The gas engine was used to increase the car’s ability to create regen by elevating the car (increases the gravitational potential), just as using the gas engine to accelerate the car increases the car’s ability to create regen by increasing the car’s momentum. What mode was the car in as the regen was created?

Think of it this way:

You arrive at the top of the mountain in Hold Mode. If the battery state of charge is at the grid power state of charge (i.e., the soc when you switched into Hold Mode) and not above it, you have two choices.

If you switch to Normal, you descend the mountain in Electric Mode, and the regen battery powered miles you drive after reaching the bottom will count as electric miles (don’t need to turn the car off and back on).

If you remain in Hold Mode, you descend the mountain in Extended Range Mode, and the regen battery powered miles you drive after reaching the bottom will count as gas miles.

If you remain in Hold Mode, you descend the mountain in Extended Range Mode. If you then stop the Volt at the bottom of the descent, turn it off and back on again, and drive off, the regen battery powered miles you drive will count as electric miles without increasing the kWh Used number.

By turning the car off and on again, the computer sees some usable power in the battery that is neither grid power or regen put there while driving on grid power (and it doesn’t remember you were in Hold Mode when the car was turned off). The kWh Used number represents a net grid power consumption (grid power used less regen obtained while driving on grid power), and this downhill-in-Hold regen power is neither, so using it gets you electric miles without changing the kWh Used number.

Of course, increasing your total electric miles without increasing the total grid power used may boost your ev mileage (and range) impressively... and because the regen was created while driving downhill in Extended Range Mode, there’s a matching reduction in total gas miles driven using the total gas used, reducing your MPGcs gas mileage. Playing games to get regen to count as electric instead of gas miles doesn’t change the actual distances your Volt has traveled on regen battery power.
 

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I'm a software engineer just like Dilbert. Just like in the Dilbert comic strip, the marketing types ask me to add features to our product.

Me: I don't really have enough data in the system to give the customer accurate displays.
Marketing: Accuracy doesn't matter, it's just to entertain the customer.
Me: Mark my words, some customers will notice the discrepancies and make my life miserable.
Marketing: We don't care, just implement it.
^THIS^

the Volt is just using an algorithm for the "real time" data it displays. It's not like it's "measuring"--it's always estimating and sometimes getting it wrong. That's why it switches to CS mode at variable kWh used (usually a range of 13.8-14.2), and we sometimes lose or gain a mile or two after parked (it's doing it's calculations and measuring the SOC).

I do think they got the algorithm a bit wrong on the ICE vs. EV question, though. The Gen 2 Volt does not seem to aggressively regen as much in HOLD (MM is different), I think it "borrows" more from the battery than it lets on.

I wonder how it would calculate the miles as EV or GAS if you used MM to "charge" to 10 miles and then partially charge it another 10 miles (total of 20 miles remaining). Never tried it, but wonder if it would keep counting as gas for 10 miles then EV for 10 miles. I'll have to give it a try since I have no life.
 

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I don't care how it counts it so long as I don't have to put too much gas in it. Gas is expensive here. Electricity is cheap.
 

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I wonder how it would calculate the miles as EV or GAS if you used MM to "charge" to 10 miles and then partially charge it another 10 miles (total of 20 miles remaining). Never tried it, but wonder if it would keep counting as gas for 10 miles then EV for 10 miles. I'll have to give it a try since I have no life.
I suspect that once you turned the car off to add the partial charge on top of the MM-recharged battery power, the car would forget how the MM-recharged power got into the battery (using gas in the generator), so none of it would count as gas miles. Some of the battery powered "electric miles" driving will increase the kWh Used number, and some will not.

The partial recharge would add grid power to the grid power remaining from the original charge. The question is, when you turned on the car, would you have a layer of grid power sitting on top of a layer of MM-recharged power sitting on top of the layer of original charge grid power, or would the grid power combine into a single layer, with the "non-grid battery power" layer sitting on top?

The entire usable battery power would be used as electric miles, but would the kWh Used number not change at all until you had used up the "MM-recharged non-grid power," or would the kWh Used number increase as you used up the partial charge’s amount of grid power, then remain constant as the "MM-recharged power was used," and then start to increase again when the soc dropped to the grid power from the original charge soc level?

My guess? There might be at least three people out there interested in learning the answer...
 
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