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I have had my 2015 Volt for 2 months. I live at the top of a 16% grade 1 mile long hill. When the car is fully charged, I go down the hill in 'L' to regen (I have had as much as 56 miles range showing at the bottom of the hill). The software defect; however, causes the energy tracking mode to erroneously indicate that the ICE was running and I get about .7 miles of ICE runtime after going down the hill in 'L'. This happens consistently every time, and I have listened carefully to verify that the ICE is not actually starting (at the bottom of the hill I hit "hold" to force an ICE start to verify that I could hear the difference and it is completely obvious when the ICE is actually running).

My concern is that this software defect is (in aggregate) causing the total reported EV range (from sites like voltstats.net) to be inaccurately reported.
 

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Wow! That is a steep hill! Not certain there is anything to be gained by charging to full capacity at the start of your drive, I believe the regen is shunted to ground if the battery is fully charged?
 

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There is a bug in how the usage is tracked on the dash, but not in how voltstats shows it. AFAICT.

You can actually have a depleted battery. Put it in MM in park and regen half the battery charge and they will all count as EV miles but show you burned gas. But you can drive around all day on a full charge if you ever went to MM or hold charge mode and they will all be gas miles even if you burned 0 fuel. Same if you drive until "emtpy" but kept the mph and range low, they still show as gas miles even if the engine never starts or is even disabled ( Engine unavailable reduced power mode )

 

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I have seen this complaint here before, I don't recall if those ICE miles influence anything else.

I think what is happening is your traction motor is in generator mode going down hill, I think it is capable of generating on order of 60 kW of power, which goes into the battery until it is at max charge level (slightly higher than it charges to on the wall outlet). Once the battery has taken all the power it can, it has to burn up that power somewhere else, so I think it uses the ICE generator motor to counteract the traction motor, which is maybe why the ICE miles count up.

A good solution might be to not charge your car fully the night before (schedule charging to end a little after you would leave).

A 4000 lb-mass car at 800 feet (estimate based on 1 mile and 16% grade) above ground level has about 1.2 kWh of potential energy stored, so this would overcharge your battery if you could put that all in the battery.
 

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I wonder if the Volt does like the Prius and uses a motor to turn over the ICE (without feeding any gas) to burn off charge when the battery is full?

As a test, don't fully charge before going down the hill.
 

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The volt will let you "overcharge" the battery. It's maximum is soft at around 80% SOC. It will let it charge over that to about 92% before it shuts off the regen and switches you to regular ABS brakes.

I've hit it going down a mountain in L, feels like the car cuts to N and then the brakes feel like a normal car. It is abrupt and IMHO a poor design if you are depending on the L regen to slow your decent and it just up and decides it's full and turns it off.
 

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Discussion Starter #7
It actually does take the additional charge. I have actually travelled 12 miles beyond the bottom or the hill (where it read 52 miles) and had exactly 40 miles remaining. Perhaps there is an ultra-capacitor in there somewhere?
 

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The volt will let you "overcharge" the battery. It's maximum is soft at around 80% SOC. It will let it charge over that to about 92% before it shuts off the regen and switches you to regular ABS brakes.

I've hit it going down a mountain in L, feels like the car cuts to N and then the brakes feel like a normal car. It is abrupt and IMHO a poor design if you are depending on the L regen to slow your decent and it just up and decides it's full and turns it off.
Interesting. Haven't encountered that yet, but I know for a fact I can get at least 6 miles more after a full charge, just by going to the bottom of my hill.
 

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I have seen this complaint here before, I don't recall if those ICE miles influence anything else.

I think what is happening is your traction motor is in generator mode going down hill, I think it is capable of generating on order of 60 kW of power, which goes into the battery until it is at max charge level (slightly higher than it charges to on the wall outlet). Once the battery has taken all the power it can, it has to burn up that power somewhere else, so I think it uses the ICE generator motor to counteract the traction motor, which is maybe why the ICE miles count up.

A good solution might be to not charge your car fully the night before (schedule charging to end a little after you would leave).

A 4000 lb-mass car at 800 feet (estimate based on 1 mile and 16% grade) above ground level has about 1.2 kWh of potential energy stored, so this would overcharge your battery if you could put that all in the battery.
Yes, that's what I was thinking as well (that the s/w engaged the ICE to add braking load, so that 'L' brakes the vehicle as you would expect it to), but since the ICE isn't actually running (I have confirmed that) the code shouldn't count it as ICE mileage (but it does).
 

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I wonder if the Volt does like the Prius and uses a motor to turn over the ICE (without feeding any gas) to burn off charge when the battery is full?

As a test, don't fully charge before going down the hill.
I think (as viking79 suggests) that the software clutches in the ICE for braking when in 'L' but the battery can't absorb all the regen (which is all fine, it's just that the s/w shouldn't accumulate ICE miles, since no fuel is being burned). The display shows (as Aseras's picture shows) ICE mileage with 0.00 gallons of fuel used.
 

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That’s not really a software "defect" but more of a complex programming issue when the only two categories are "electric" and "gas" miles. When you drive down a long hill and regeneration is occurring, the ICE is not running. Downhill distance = electric or gas miles? Distance driven on the regenerated battery power = electric or gas miles? Should the attribution depend on the "ICE vs battery power" category in use at the moment the downhill regeneration kicked in?
 

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What it says in car and what voltstats records are two different things. Voltstats will record everything as EV unless the engine actually turns on completely (switches to blue gas pump view)
This means that engine maintnenace and ERDTT, which actually do start the engine and burn gas/rack up gas miles, are recorded as EV only on voltstats.

This will have two outcomes:
1) your voltstats EV miles are unaffected
2) your in car lifetime mileage won't change (its still x gas burned over y distance regardless of which bucket they're tallied under)

I wonder if the Volt does like the Prius and uses a motor to turn over the ICE (without feeding any gas) to burn off charge when the battery is full?

As a test, don't fully charge before going down the hill.
As the volt has two motors, the engine is not required at all. When the battery is max, it will run the motors against each other to burn up electricity being generated and slow the vehicle at the same time
 

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I have had my 2015 Volt for 2 months. I live at the top of a 16% grade 1 mile long hill. When the car is fully charged, I go down the hill in 'L' to regen (I have had as much as 56 miles range showing at the bottom of the hill). The software defect; however, causes the energy tracking mode to erroneously indicate that the ICE was running and I get about .7 miles of ICE runtime after going down the hill in 'L'. ....

My concern is that this software defect is (in aggregate) causing the total reported EV range (from sites like voltstats.net) to be inaccurately reported.
this oddity has been seen by others living at the top of a long hill. it appears to be an artifact of the algorithm that tracks where the energy in the battery originally came from. My suggestion is to not worry about what is "reported" in volt stats or anywhere else, you know how much gas you used, and if you use one of your trip odometers as a lifetime usage tool (I do, I reset "B" when I bought the car and have not reset it since) you will always know your lifetime miles and lifetime gas usage. That is what matters to some. others have suggested that you set the charging system to leave the battery not full when you leave in the morning. if you want to maximize your energy efficiency, that is a good idea. Does the behavior change depending on whether you were in Gas mode or electric mode on the way up the hill the night before? I expect not, but that may be part of the oddity.

Wow! That is a steep hill! Not certain there is anything to be gained by charging to full capacity at the start of your drive, I believe the regen is shunted to ground if the battery is fully charged?
this is not correct, there is no shunt to ground or resistor bank. When the system decides that the battery should not be charged further, it uses the 2 electric motors to driving against each other, the excess energy becomes heat in both and is removed by the active liquid cooling system. Diesel-Electric locomotives have massive air cooled resistor grids used to keep speeds in check on long down grades. In some mountainous areas, these can be seen at night, glowing red, on long down grades. Not so our cars...

I have seen this complaint here before, I don't recall if those ICE miles influence anything else.

I think what is happening is your traction motor is in generator mode going...Once the battery has taken all the power it can, it has to burn up that power somewhere else, so I think it uses the ICE generator motor to counteract the traction motor,...A good solution might be to not charge your car fully the night before (schedule charging to end a little after you would leave).
...
Good idea on the solution, as you note the smaller electric motor (that associate with the ICE) provides the place for the energy to go into heat, without being clutched into the crankshaft.

I wonder if the Volt does like the Prius and uses a motor to turn over the ICE (without feeding any gas) to burn off charge when the battery is full?
...
No it doesn't.
 

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Discussion Starter #14
That’s not really a software "defect" but more of a complex programming issue when the only two categories are "electric" and "gas" miles. When you drive down a long hill and regeneration is occurring, the ICE is not running. Downhill distance = electric or gas miles? Distance driven on the regenerated battery power = electric or gas miles? Should the attribution depend on the "ICE vs battery power" category in use at the moment the downhill regeneration kicked in?
The answer seems straightforward to me. If the ICE isn't burning fuel, it isn't running. It should continue to apply that "braking" time against the oil consumption for sure, since the ICE is moving, but it is clearly erroneous when you can get 14 miles of ICE with 0.00 gallons used.
 

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I'm not so sure about a defect per se. It tallies it a gas miles but doesn't indicate any fuel consumed. I figured it's an attempt to account for regeneration and still accurately account for the electrical energy consumed from the grid. Seems like it could be done better.
 

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Keithmoon, the fuel tracking programming must be rather complex. Last year I postponed an FMM and attempted to use up my old gas by experimenting with MM. After driving my 2012 Volt until the usage screen was showing 37.2 electric miles and 8.7 kWh Used (i.e., AFTER the battery soc was below that maintained by MM but above that where the normal switch to ICE is made), and 0 gas miles/gal used, I pulled into a parking spot and switched into MM.

The ICE started and the usage screen noted the gas used for the MM recharging... 0.03 gallons, 0.07, 0.10, 0.13, 0.17, 0.23, then 0.26 (I captured screen shots). Shortly thereafter the battery attained the MM-maintained soc and the ICE shut off.

I switched Normal and drove off. The electric mile count rose... 37.9, 38.0, 38.7, then 42.0... without using any battery or gas fuel at all (i.e., the kWh Used remained at 8.7 for that many miles)... By the time the electric miles reached 46.8 the power usage had finally started moving again (8.9 kWh Used now). 2011/2012 Volts are capable of recording MM-recharged power as electric miles, and using this power for electric miles does NOT increase the kWh Used number in the 2012 display. My Volt’s behavior suggests the computer flagged the soc at which I started the MM-recharging process, then waited until the MM-recharged battery soc had dropped again to that point before restarting the display screen counting of kWh Used.

I repeated this exercise twice more (park before ev miles reach 0, MM-recharge, drive) that day. When I arrived home and plugged in to recharge, the usage screen showed 9.3 kWh Used to drive 68.9 electric miles and 0.96 gallons gas used to drive 0 gas miles. Based on how well my personal records tracked my gas/electric numbers in voltstats.net back when I had an OnStar account, what it said in my car (68.9 electric miles, 0 gas miles, and 0.96 gallons of gas used that day) WAS also what Voltstats recorded about my car. I didn’t check, but suspect that because of the 0 gas miles, Voltstats did not indicate any break in my "days driven without using gas" string in progress at the time.

My understanding is that the computer programming was modified for post-2012 Volts to avoid counting MM-recharged miles as electric miles (throws off the MPGcs). One can only contemplate how complex the algorithm would be to track ice vs gas miles when the vehicle is shifting in and out of Hold mode (battery to ICE and back) at various speeds in various types of terrain at various soc readings with various types of regeneration occurring at various points in the travel. Then toss in driving downhill when the battery is fully charged and decide how to record the miles if the battery is too fully charged to allow regeneration to subtract from the displayed kWh Used number where it then could end up as electric miles.
 

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I have had my 2015 Volt for 2 months. I live at the top of a 16% grade 1 mile long hill. When the car is fully charged, I go down the hill in 'L' to regen (I have had as much as 56 miles range showing at the bottom of the hill). The software defect; however, causes the energy tracking mode to erroneously indicate that the ICE was running and I get about .7 miles of ICE runtime after going down the hill in 'L'. This happens consistently every time, and I have listened carefully to verify that the ICE is not actually starting (at the bottom of the hill I hit "hold" to force an ICE start to verify that I could hear the difference and it is completely obvious when the ICE is actually running).

My concern is that this software defect is (in aggregate) causing the total reported EV range (from sites like voltstats.net) to be inaccurately reported.
When you drove up the hill to your home where you driving using the ICE?
 
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