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Discussion Starter · #1 ·
Anybody else actually watch the "Power Flow" screen during ICE operation?

Yesterday, I exhausted my basic EV battery range, and operation has smoothly transitioned to ICE drive. BUT, I found us on several long downhills, where I happened to be switched on the central display to the "Power Flow" screen, and what did I see there?

I saw the ICE shut down as the battery was getting REGEN from the downhill, and upon hitting the flat road again, the car was STILL IN EV MODE, even though the more detailed Energy State (?) screen did NOT SHOW any additional EV miles !!!! The Volt actually ran almost two more miles in battery power mode with NONE OF THAT REGISTERED as "battery miles," but rather it turned to significantly helping my recorded "gas mpg."

Our trip was from Sacramento to Daly City in the S.F. area and back, and the displayed gas mileage for the 122.5 miles of supposedly gas driven distance used 2.78 gallons of fuel for a computed mpg of 44.06. I had a full charge on leaving Sacramento and got about 26 more battery miles for the return drive from using my 110V cord while the car was parked at our relatives house in Daly City.

BUT, the displayed "miles for fuel used" does NOT RECORD the almost 4 miles of extra total battery power driving that happened due to a "hidden return" to EV operation coming from the REGEN ENERGY produced after the return drive switch from the 26 miles exhausted battery range to the "ICE OPERATION."
 

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Anybody else actually watch the "Power Flow" screen during ICE operation?

Yesterday, I exhausted my basic EV battery range, and operation has smoothly transitioned to ICE drive. BUT, I found us on several long downhills, where I happened to be switched on the central display to the "Power Flow" screen, and what did I see there?

I saw the ICE shut down as the battery was getting REGEN from the downhill, and upon hitting the flat road again, the car was STILL IN EV MODE, even though the more detailed Energy State (?) screen did NOT SHOW any additional EV miles !!!! The Volt actually ran almost two more miles in battery power mode with NONE OF THAT REGISTERED as "battery miles," but rather it turned to significantly helping my recorded "gas mpg."
That is so coincidental because I traveled 50 miles yesterday and noticed and was "annoyed" by the EXACT same thing. Powerflow and my ears showed I was in CD 'battery' MODE but all my miles registered to CS 'gas gen' MODE. Makes my stats look worse.
 

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That extra energy gained during regen, was produced from kinetic energy supplied FIRST, by the ICE....so it's only fair to add that extra efficiency back to the ICE mpg calculation.

Those extra EV miles are simply a reflection of the cars ability to capture braking energy that would normally be wasted by a non hybrid car. The EV miles should not count toward total EV miles because the energy used to get the car "up to speed" or "up the hill" presumably came from gasoline...not the battery.
 

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I too took our longest drive in our Volt this weekend, about 233 miles, getting 50.5 miles electric at the start. But, there were occasions when I suspected that I was getting "extra" miles from the brake regen while driving on gas?
 

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I saw the ICE shut down as the battery was getting REGEN from the downhill, and upon hitting the flat road again, the car was STILL IN EV MODE, even though the more detailed Energy State (?) screen did NOT SHOW any additional EV miles !!!! The Volt actually ran almost two more miles in battery power mode with NONE OF THAT REGISTERED as "battery miles," but rather it turned to significantly helping my recorded "gas mpg."
I see this all the time. That's why I am amused by all the posts of those using mountain mode on Kansas-like flat roads, or driving all the time in low.

Exactly right on the regen added back to the battery - it happens as well in D with normal braking, or while just "coasting" down hills using cruise control. Did you also notice how if you hit a traffic jam on the freeway while in range-extended mode, the vehicle will shut off the engine and run on battery for a couple of miles of stop and go, even running the AC on comfort? More efficient that way, not running the engine and having to get rid of engine heat while stopped - better to draw on the battery reserve.

There is the EV (CD) mode and the range-extending (CS) mode. Once you've exhausted pure EV, the gas gage comes up and the miles are counted as the blue portion of the ball. Only fair, because the vehicle is always running on electric traction power; the only difference is that the ICE, rather than the electric power grid has provided the energy to maintain the minimum balance in the battery, and regenerative braking helps . Always a reserve - kind of like your checking account - never want it to get down to zero.

The Volt is well-engineered to maintain maximum efficiency in both CD and CS modes (yes, I expect continuous improvement in future model years). I say just "chill out" and let the Volt's brains do the thinking instead of trying to second-guess when it should switch modes, how much energy the ICE should add to the battery (mountain mode), when to use L (braking without the brake lights) vs. Drive, etc.
 

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The discussion that is represented by the previous posts is in fact discussing the Hybrid operation that occurs while driving in CD mode. This is what is confusing people as to what the Volt is. The Volt in its design includes features of both Hybrids and pure EVs and is the main argument that we see on the discussion forums. The Volt in its design, draws on the Hybrid and EV worlds, but is not in either camp. Where as a Prius of a Fusion uses the ICE most of the time and blends electric power to increase efficiency, the Volt is an EV most of the time and a Hybrid part of the time. The Volt deserves a new classification based on how it operates. I have proposed this before, and I feel that this needs ot be done to give it a proper identity in the automotive world. So what I propose is that we begin calling cars like the Prius and Fusion - ICE Hybids, and that the Volt be called - PEV Hybrid. The rules would be as follows:

1) ICE Hybrid - Runs 90% or more on ICE
2) PE ICE Hybrid - Runs EV mode for a distance of 25 miles or less
3) EV Hybrid - Can run EV mode 100% of the time at any speed for 25 to 60 miles, runs series/parallel Hybrid mode when needed.
4) EV - Pure EV, no ICE range of 60 miles or better on single charge.

I am open to suggestions, so comments are welcome. Since the Volt is a game changer, why not make sure that we classify it correctly. The Volt is the link between EV and Hybrid and itself may be a solution that will only be around until the USA has a charging infrastructure for rapid charging and batteries that can take the abuse of rapid charging. I strongly believe that the Volt deserves its own clasification.


Pat
 

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I strongly believe that the Volt deserves its own classification.
What's wrong with EREV (or the Karma's more evocative EVER)?

And just to be picky, while you suggest calling the Volt a PEV Hybrid, you don't list PEV Hybrid amongst your four choices... In your list I believe you include the Volt in the classification of EV Hybrid (#3).
 

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That extra energy gained during regen, was produced from kinetic energy supplied FIRST, by the ICE.
Exactly. EV miles are miles powered by the wall plug. Miles powered by the ICE, even via a detour through the battery, are ER miles.

A standard Prius never produces EV miles. It has no plug. Once the Volt drains the plug charge it effectively becomes a Prius-like hybrid. It makes no sense to speak of EV miles after that point just as it makes no sense to speak of EV miles for a Prius.
 

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I've experienced this too, but consider it operating as intended for the reasons stated above.

If you'd like to experiment with it more directly, try switching to MM before EV range depletes fully, the gauge will show a switch to CS mode but if you switch back to normal it will revert to CD mode showing electric miles (and depending how long you stayed in MM, probably more than you started with). However, do the same experiment after fully exhausting the EV miles and the gauge will never switch back to CD, no matter how high you raise the SOC with MM. Finally, fully drain the CD range in normal, then run in MM for 10-15 minutes, then switch back to normal, you're now running in electric but recording miles as CS. Immediately turn the car off and back on again and it will switch to CD and record miles as EV.

CS mode does not equal gas as power source, it just changes the algorithms that control from which source the car will draw energy under different parameters.
 

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Discussion Starter · #10 ·
One other observation about this impressive Volt EVER technology (Yes, I like that version better than the other options herein mentioned):

This seems to help or even fully explain why almost all of us are getting better ICE mileage than the EPA ratings for the Volt. The EPA test scenario does not give cars a chance for much in the way of regenerative power activity, and thus the EPA numbers significantly underestimate the "real world" gas mileage potential of the Volt powertrain with its ability to regen additional battery power miles !!!!
 

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EPA numbers significantly underestimate the "real world" gas mileage potential of the Volt powertrain with its ability to regen additional battery power miles !!!!
While yes, it does regen additional battery power miles, If we assume the trip odometers to be accurate in calculating instant ICE mpg, that mileage takes a significant hit while running in MM mode, at least until the battery has been charged to MM minimum. I've tried numerous experiments resetting one trip odometer when the Volt switches over to the ICE and while running in normal mode I routinely avg. 37 - 39 at 70mph, in MM those numbers drop to about 25mpg until the SOC of the battery has been returned to whatever value MM keeps it at. That being said, my trip in this condition is only about 15 miles so I don't know what the instant mpg will ultimately return to.

Unfortunately I've not yet had the opportunity for a road trip where I can try this over an extended range so I don't know how the 15 - 20 minutes of recharging the battery affects overall long distance mpg.

You may be right. I'll be glad when I have the opportunity to test this.
 

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What's wrong with EREV (or the Karma's more evocative EVER)?

And just to be picky, while you suggest calling the Volt a PEV Hybrid, you don't list PEV Hybrid amongst your four choices... In your list I believe you include the Volt in the classification of EV Hybrid (#3).
Hi Rusty, No problem with your comments, actually I was thinking that PEV Hybrid was more appropriate after the fact. Did not have achance to go back and edit, as it was time to get back to work. EREV is fine, but I guess it does not tell whole story to me as to what we are dealing with. I put definitions to show what each means as respect to energy usage. Most people I talk to about the Volt have no clue, and some are very technical and some have been influenced by the right wing news media. Talking to those people is a real trip, if you know what I mean. Thanks for your comments, I apprciate the input.

Pat
 

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While yes, it does regen additional battery power miles, If we assume the trip odometers to be accurate in calculating instant ICE mpg, that mileage takes a significant hit while running in MM mode, at least until the battery has been charged to MM minimum. I've tried numerous experiments resetting one trip odometer when the Volt switches over to the ICE and while running in normal mode I routinely avg. 37 - 39 at 70mph, in MM those numbers drop to about 25mpg until the SOC of the battery has been returned to whatever value MM keeps it at. That being said, my trip in this condition is only about 15 miles so I don't know what the instant mpg will ultimately return to.

Unfortunately I've not yet had the opportunity for a road trip where I can try this over an extended range so I don't know how the 15 - 20 minutes of recharging the battery affects overall long distance mpg.

You may be right. I'll be glad when I have the opportunity to test this.

I have only been testing at low speeds, mostly in the 25 to 45 MPH range with some short 10 to 20 miles at 65 to 70 MPH, over a distance of 50 to 100 miles. In the three instances I have experienced my MPG was in the range of 75 to 90 MPG with the lower being the highest distance. MM used on lowspeed runs on relativly short distances 5 to 10 miles have been interesting. Last run I did I turned on MM at 16 miles remaining. When the care switched over to the ICE MPG came in at 27 MPG, when the battery was SOC reached it's buffer limit. From that point on the MPG up through 35, then 45, then 55 then leveled out a 61 MPG at 10 miles of travel. I drove very conservativly at about 35 MPH. The ICE would cycle a few times and the MPG would drop, but overall it kept rising. I think that most people do there MM testing at highway speeds and not at low. Most secondery roads in Mass. are limited to about 35 MPH anyway, but I see some very high numbers doing this type of driving. I Wonder if other Volt drivers are doing low speed testing?


Pat
 

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Discussion Starter · #14 ·
@JeremyK
I cited you in the article just posted on Green Car Reports describing this "regen miles added" process. Here is the link:

http://www.greencarreports.com/news...t-volts-extra-free-electric-miles-in-gas-mode

I got a personal note from Felix Kramer who regularly drives back and forth between SF and Lake Tahoe; he is getting 50+ mpg on his return drive from Lake Tahoe with all the extra "regen miles" from those big downhills.
 

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Nice article George, thanks for the link. I might point out that the EPA cycle does contain many deceleration events, which should result in the capture of some additional energy over a normal ICE-based car, thereby increasing the Volt's overall efficiency.

The beauty of the Volt (and Leaf for that matter) is they can really pull in a large of amount of regen charging compared to a Prius, which could easily top off its small battery during a long downhill stretch. The Volt will never (practically speaking) run out of "room" to store regen energy (unless perhaps if you started at the top of a very very tall hill with an already fully charged battery).
 

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Ref previous mention of "instant" MPG on the odometer....

The Volt's odometers do not show instant (instantaneous) MPG like other cars do because with the ICE cycling itself on and off over time any such reading would be meaningless. What it does show you is a continuously updated average MPG, which is meaningful.

Ken. # 1228
 

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The Volt's odometers do not show instant (instantaneous) MPG like other cars do because with the ICE cycling itself on and off over time any such reading would be meaningless.
I don't think it'd be meaningless. But I do think it'd scare the pee-waddle-do out of the average car driver, because they'd freak out with it saying "20... No... 60... No... 45... No... 15... No...". Reading a Volt's instantaneous MPG (like reading its instantaneous KW) takes a self averaging mind...
 
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