I take frequent highway trips in my 2011 Volt. Rather than trying to build range with mountain mode I preserve range with mountain mode. I put the car in mountain mode at the start of the trip. It will switch to ICE with about 4 bars of range left. After that just leave it in mountain mode. After gas stops you have to remember to reset mountain mode. I do this for two reasons #1 as you describe to not have the engine running in city traffic after destination area is reached. #2 I do not like parking overnight with the HV battery at its minimum, when no charge outlet is available. If your trying to build range at highway speeds as you describe of 78-82 mph, in mountain mode, you are running the ICE hard and hot. I would avoid doing that regularly. Occasionally in cool weather probably OK. Or building range on side roads at 45-55 mph is probably OK. But at 80 that’s asking a lot to maintain that speed and charge the battery. Fuel mileage at 78-82 mph can vary a lot depending on wind direction, terrain, and tire type and tire air pressure. My 2011 Volt gets anywhere from 33 to 37 mpg on the freeway at those speeds.

 

I take frequent highway trips in my 2011 Volt. Rather than trying to build range with mountain mode I preserve range with mountain mode. ...

That's the best advice. In addition, you will maximize your fuel usage this way verses depleting the battery and having the engine work hard to catch up.

Alternatively, just put it in Hold Mode whenever you're on the highway. I do this for longer trips. At the end of the return leg, I'll put in back in Normal to use up any remaining battery.

 

On my 1st gen is a highway consumption 6,2litres/100km (130-140km/h)

And I agree , on the highway in Mountain Mode, the charging is veeeeeery slow and ICE running on (strange) high rev almost all the time. I tried it for few minutes and feeling bad because of ICE, so I switched mountain mode OFF and continued on Normal Mode. After few minutes in MM, it added cca 6km range only. I got not reduced power message in normal mode with discharged battery, even on highway speeds, so I didn't need to torment the ICE.

 

Car's trying to generate a couple of kwh WHILE you're flying down the highway, and terrain's gonna impact that too, uphill vs downhill. I can't say whether you damaged anything (though I suspect no, without seeing the same slowness doing MM at 40 MPH instead of "high speed"), but "engine running at high speed for a long time" is ... absolutely to be expected.

 

This engine in the turbocharged version, used in the Cruze, is prone to overheating and blowing the head gasket. I wouldn’t take that chance of running it super hard like that at 80 mph, and trying to generate a battery reserve. If you’ve ever tried climbing steep terrain without mountain mode, no battery reserve, and that thing screaming like hell......not good.

 

While running, the ICE acts as an electric generator, so it rev's up to create electricity. It will also do this standing still at a stop light if the car needs some juice. It's not the normal experience of the ICE revving in response to your foot on the go pedal.

The car is designed to use the ICE in MM as a generator. Using it will not harm the engine. There could be other issues with an ICE of course (spark plugs, coolant, etc.), but using MM on long drives is an anticipated and designed for use.

 

TexasTed,
You were operating the vehicle as it was intended to be used, so I would not worry. The generator is about 50kW, which is about 67hP. Add in a couple percent for generator losses, so maybe the output is around 70hP. This is all controlled by the generator output and the fuel input being balanced. The car will not allow itself to operate in a harmful state (i.e. redline). I think the engine revs up to around 4,000rpm. That should not be a huge issue.

The other part of the question... your MPGs do seem a little low, but not too crazy. Trying to rebuild charge while also operating at 80mph will cause low MPGs, it is a double whammy - propelling the vehicle through the air where you might expect 35MPG while simultaneously trying to add back charge will certainly consume more fuel. Try to put it into mountain mode (or Hold if you have it - I have a 2011 Volt, so I used the MyGreenVolt app's Hold mode with some success, although it does kick off occasionally, and you have to restart it if you really want to stay in Hold) before you get below 4 bars to get an idea of what your highway MPGs are without the rebuilding of battery charge. Also, higher speed driving will kill MPGs (plus terrain, climate control, wind, etc...). I am a recent first time Volt owner (and a data geek, so I have been watching my MPGs when I do longer highway trips. Here is the result I observed from a recent trip from Colorado Springs (6,800'), over Monument Hill(7,350'), thru Denver (mile Hi!), to Fort Collins,CO (5,000') and back: (copied from my previous post)

"I made a 262 mile (41.7 electric and 220.3 gas) round trip to visit my daughter (~2,000' lower elevation over 120 miles) and was surprised to get 49.1 MPG on the way there, and 46.0 MPG overall for the roundtrip. (Edit- should have said gas only mpg, not combined with electric miles) I am pleasantly surprised! I was driving close to 65 MPH for about 110-115 of the miles each way."

I was driving for economy at a time where I could drive below the posted speed limit (75) and not cause traffic issues. It is really eye opening the difference in economy between 65 MPH and 80 MPH. I have not done a test, but I suspect I would only get 30-35MPG at 80 MPH
MikeB

 

So, here's the thing... after a lot of experimenting on my eastward drive, I concluded that the best combo for high-speed highway driving is 'L' and Sport mode. I avoid 'L' around town because I find it lurchy in stop-and-go city traffic. But above 50 mph, when traffic bunches and slows down (like when one 18-wheeler tries to pass another), all you have to do is ease off the accelerator and the car slows smoothly, without weight transfer, recapturing energy in the process. Sport is helpful too. Because when the left lane clears, it takes a BOOTFUL of throttle to accelerate from 70 to 80 in Tour or Mountain at the same rate as a "normal" car. The throttle re-mapping that takes place in Sport mode makes it much easier to tap into those extra kW at highway speed. Honestly in L-Sport, it feels like a different (and much sportier) car. So that's the experience I want when I'm cruising the flatlands, trying to stay with 80 mph traffic.

What I also want, is silent all-electric operation when I exit into a town or city. So my strategy was: L-Sport on the highway, switch to Mountain mode about 20-25 mins before I exit to build 3-4 bars of battery, and then Tour (normal) for urban maneuvering. In the future, extended-range EVs (i.e., plug-in hybrids) might use GPS to "geofence" themselves into this operating pattern. It may even be necessary for emissions certification, as high-pollution areas ban ICE operation within city limits.

What concerns me is that it seems like Mountain mode somehow became less effective after my high-speed stint on Saturday afternoon. In the earlier part of my trip it seemed that I could consistently build 4 bars in about 20 minutes, and 2-3 bars in just 10-15 mins, even on flat terrain. But by the end of the trip, the powertrain struggled to build 3 bars even after 40 minutes, and the ICE seemed to be working harder. Is there some kind of clutch or friction surface that could have worn out from repeated high-RPM engagement, which is now slipping and therefore reducing my "on-the-fly" charging efficiency? If so, I would think this would throw an error code. Bottom line: is there any definitive criteria to gauge whether Mountain mode is working correctly?

I still haven't been able to plug in since my trip, so I don't know if the battery will charge to more than 4 bars. No "check engine" light or warning messages, and except for the perceived slower charging in MM, car drives ok. Appreciate the feedback.

 

What concerns me is that it seems like Mountain mode somehow became less effective after my high-speed stint on Saturday afternoon. In the earlier part of my trip it seemed that I could consistently build 4 bars in about 20 minutes, and 2-3 bars in just 10-15 mins, even on flat terrain. But by the end of the trip, the powertrain struggled to build 3 bars even after 40 minutes, and the ICE seemed to be working harder. Is there some kind of clutch or friction surface that could have worn out from repeated high-RPM engagement, which is now slipping and therefore reducing my "on-the-fly" charging efficiency? If so, I would think this would throw an error code. Bottom line: is there any definitive criteria to gauge whether Mountain mode is working correctly?

Bottom line, I’m not sure what you think Mountain Mode "does."

Yes, you can use an OBD reader and an app that shows you the raw SOC reading of the battery to determine whether or not Mountain Mode is doing what it is programmed to do.

The Volt (and the ELR) are programmed to maintain the SOC at the level it is when you transition from Charge Depleting Mode to Charge Sustaining Mode. When you reach the bottom of the Electric Mode window, the car transitions from battery to gas (CD to CS).

The Electric Mode window (the "usable window," Electric Miles, kWh Used) is the portion of the battery full capacity that GM has programmed for use in Electric Mode driving. Wikipedia says this is 65% of the full capacity for Gen 1 Volts. As far as I know, the Gen 1 Volt is "fully charged" at the ~85/87% SOC level, and the bottom of the Electric Mode window is at the ~20/22% SOC level, i.e., the Gen 1 Volt normally transitions from CD to CS mode at the ~20/22% SOC point (those points may differ in the ELR).

The primary thing that Mountain Mode "does" when you switch to MM is to increase the "CD to CS mode" transition point SOC level from the 20/22% SOC bottom of the Electric Mode window up to the 45% raw SOC level (according to Wikipedia). Maintaining the SOC level at 45% keeps additional electricity in the buffer that can be used by the motor when generator output is insufficient to meet performance demands.

Note that by increasing the "maintained" SOC level from 20/22% to 45%, you "preserve" 23-25% of the 65% Electric Mode window for your extended range driving, i.e., 23 or 25/65 = 35 or 39% of the full charge. That would be displayed on the battery icon as 4 bars, since it’s more than 30% of the usable window, but it is only a "partially filled" fourth bar. If you are driving aggressively, you may easily drain that 4th bar.

Undoubtedly, switching to MM also modifies the programming that controls how aggressively the system attempts to maintain the SOC at that point. MM was intended for use in high power demand driving circumstances, where maintaining that additional power in the battery buffer would be important. When driving in MM you may, for example, experience less aggressive acceleration as the system prioritizes the maintenance of the higher SOC level over maximum performance. You’ve already noted this by writing, "it takes a BOOTFUL of throttle to accelerate from 70 to 80 in Tour or Mountain at the same rate as a 'normal' car."

Note that if you switch to MM with a full charge, nothing changes... you remain in Electric Mode, and the electric range decreases because the car switches from CD to CS Mode at a higher SOC point (you can get that range back by switching out of MM and back to Normal).

If you switch to MM with a fully depleted battery, the car is already in CS Mode. Switching to MM moves the "CD to CS SOC point," and the normal system programming kicks in, recharging the battery to, and then maintaining it at this higher SOC point. You can’t get electric range back by switching from MM to Normal because you’ve already used all the grid power that was stored in the battery. You may not even be able to use that MM-recharged battery power until you turn the car off and restart it. Not using that battery power would lower your "gas" mileage because you’ve used the gas to recharge the battery but have not yet driven those Gas Miles (battery-powered miles created by using gas).

It is possible to use MM to recharge a fully depleted battery while the car is parked (the video shows that a 2012 Volt can be MM-recharged in 15 minutes using 0.36 gallons of gas). It seems to me that the same recharging via MM done while the car is being driven should not increase the amount of gas used for the recharging, so there should be no impact on your MPGcs (gas mileage while using gas) if the Miles you drive on the MM-recharged battery power are included in your Total Gas Miles. On the other hand, it may take longer to recharge via MM if the generator output is also trying to generate the power needed to keep the motor propelling the car at 70-80 mph.

On the other hand, if you recharge via MM, then stop somewhere, when you restart the car, the computer will now use and record the MM-recharged battery miles as Electric Miles (with no increase in kWh Used), which messes up both ev and gas mileage numbers.

 

Back when we started with the 2011-2012 volts
one of the original members reported on driving down Pikes's peak in L
the Range was zero at the top - I forgot how many mile he said it took to full.
----
Off topic but another volt driver charged up while visiting a nuclear power plant.
(still had a normal full charge range)

 

The gas/ev accounting does differ between early and later Gen 1 Volts, between 2011 and most 2012, and all the rest of them. The early ones are much simpler in their accounting, and a lot of those protections from totals being gamed out just aren't there.

 

wordptom I certainly understand what MM does. I read the owner's manual several times, watched videos, and even reviewed technical papers that compare the Voltech 4ET50 to a similar system in Honda's hybrids. Personally I don't care about the accounting of "electric" vs gas miles. It's nice to be able to build up a battery charge for later urban use, and IMO the sound of the gas engine is much less intrusive at highway speed, so that's when I would prefer to do it.

Your post eventually gives me a benchmark. It seems that one possible diagnostic criterium could be whether it recharges (presumably to 45%?) in 15 minutes while parked. That's assuming that the 2014 ELR and 2012 Volt have similar hardware and programming.

That still doesn't verify the health or efficacy of any clutch pack(s) that apply to enable charging while underway, particularly in when driving in 'L' at high speed. If those clutches are slipping, the ICE may keep trying to spin the generator, and it may not be turning fast enough to build a charge. It could also be that the power electronics are not accepting the charge, or they are reducing the charge rate due to heat soak? etc. You would hope that the engineers built in a test for expected vs. actual generator output, and a failure would throw a code or warning message.

Because of headwinds, variable grades, traffic, etc., I guess it's difficult to field-test this without two similar cars following each other "caravan style." My concern is based on perception alone. However, I can tell you that by the end of my trip the car was struggling to get 4 bars, and it didn't seem that way on the eastbound trip (different route and conditions.) If I had a known, consistent use case like a daily commute, I would know for sure whether accumulated wear or some type of internal failure has permanently reduced the efficacy of "on the fly" charging in Mountain mode.

Unless someone else in Dallas / Fort Worth wants to caravan with me for 20 minutes, or a tech knows of a diagnostic test, I guess I won't find out until I try to climb Loveland Pass later this year!

 

TexasTedS,
The way I tend to view it is that switching to MM changes one setting (the switch to gas point), and the normal system operation takes over from there. What you can do by using MM to change that setting (e.g., recharge a depleted battery for later use or because you aren’t able to recharge from the wall plug) is a different discussion. The gas/electric accounting matters only to the extent that it impacts the vehicle mileage stats. Using MM could be influencing the gas/ev mileage if the MM battery use gets credited to the "wrong" fuel.

You provide some good points to ponder. The only physical connection the Gen 1 Volt gas engine has to the propulsion system is when it is clutched to the smaller motor MGA. When the system is extending the range, however, the computer is continually adjusting the configuration and balancing "efficiency" against "performance demand." At times, that means one-motor configuration (engine clutched to MGA), and at other times, split-power configuration (engine clutched to MGA clutched to the ring gear). Freeway driving with portions of just cruising along mixed with portion of passing other vehicles can involve lots of use of the clutches. Then add in the dynamics of L-level regen creation when the foot eases off the throttle... Any questionable performance by any of the clutches could impact the results.

Another thought that came to mind was that Erick Belmer’s 2012 Volt "Sparkie" gave up the ghost after 400K+ miles, and the group that bought it determined that its generator motor was faulty. There was no code thrown to indicate this. Is it possible that your ELR’s motor A is starting to fail? If the engine is "cranking" the generator properly, is the generator’s output level up to expectations? Is the engine providing the expected level of cranking torque?

The Volt’s larger motor MGB gets far more use than does the smaller motor MGA (which gets very little in Electric Mode, except at high speeds, then constant use as a generator when extending the range). I don’t remember reading threads in this forum regarding motor problems, except for Sparkie’s issue.

How do you test for proper generator operation? How do you confirm the engine is properly clutched to motor A? If MGA is rated for a maximum 55 kW output capacity, how do you determined that it continues to provide that capacity?

Performing a Mountain Mode recharging of a fully depleted battery while parked would provide some benchmarks for your ELR... the time needed, the Gas Used (your larger battery - 16.5 kWh vs my 16.0 kWh - may require a wee bit more recharging time/gas, and remember that the amount of Gas Used increases by increments greater than .01 gallon). I have monitored this MM recharging a couple of times in my 2012 Volt, and when the engine stops running, indicating the MM recharging is complete, the app tells me the SOC is just over 43%, not exactly at 45%. I suppose it is possible the app’s algorithm thinks the SOC is at 43.+%, and the Volt’s Battery State Estimate Algorithm thinks it’s at 45%, or perhaps 43.+% is just where it stopped on those couple of occasions.

 

Thanks tom. My car has 44K, that's a lot different than 400k. It's hard to believe that one afternoon of 80-mph driving with several applications of regen braking could wear out the clutches, but you never know.

What app are you referring to? Is this in the infotainment center, a phone app, or some kind of 3rd party reprogramming or diagnostic software? (I had a program like that for my previous car, a Mustang.) Thanks for the great input.

 

Some years ago I heard of the mygreenvolt app, an app to be used with a bluetooth capable OBD reader and an android gizmo (some of the Volt related apps don’t like to work with a tablet-sized screen, so I use a cheap android phone with no sim card). It provides helpful information, such as the raw and usage SOC readings and the min/av/max cell voltage readings of the cell pack, plus other "real time" data as you drive (you can even set it to play a sound file when the friction brakes are applied). I bought an inexpensive OBDII bluetooth capable reader on Amazon that worked (some don’t) with my car and the app. I’ve used the app to determine that my Electric Mode window was indeed (in December of 1999) occupying the 22% to 87% region of my battery’s full charge. Other apps also do various things... the Torque Pro version ($5) of the Torque app provides the SOC readings plus other data points. There might be other apps out there that also provide raw SOC readings.

The current version of the mygreenvolt app for android does NOT provide the raw SOC readings (I’ve never found helpful the SOC readings for the usable window), but the older version I still have does, and the apple version of the app does, too, I think. It is said that if the Volt’s cell pack voltage readings have a delta greater than 121 mV (max - min) during the cell balancing procedure an error code will be thrown, suggesting that if the difference is less than 121 mV, things are ok. The current mygreenvolt app offers you the option of paying $1 for an upgrade that allows the app to provide you with a screen showing the individual cell voltages of each of the 96 cells in the pack (so if one cell is way way off, you know which one).

One additional thought came when I thought of asking if the engine was providing the expected level of cranking torque... is it possible during the last trip you got some bad gas, or put in some regular instead of premium, or it’s finally time for an oil change or a new spark plug? If the engine can’t crank the generator properly, the generator output might not be where it should be.

 

The computer says oil life is at 56%. The oil is over a year old. But the previous owner seldom used the ICE (113 lifetime MPG) so I would imagine that the motor's in great shape.

In some of the states I drove through, the readily-available "premium" was 91. Assuming that what came out of the pump matched the label, that still meets spec for our cars. But if the engine knocks more on 91 than it does on 93, etc., the computer may retard spark timing which reduces horsepower and economy.

I'm starting to think that over the course of my trip, as I got more comfortable with the car I just started driving it faster. That, plus the flatter terrain with fewer downhills (increase in total elevation going west) and a slight headwind reduced the opportunity for energy recapture.

I'm definitely going to check out the phone apps. Maybe one of them has advanced diagnostic capabilities. I LOVE the idea of an audible warning when the car switches from regen to friction brakes, why did they remove that feature!? After 10 months I'm still struggling with the brake feel around town. I even asked the dealership if there was an updated calibration to address this, and he said "it's a hybrid, they're all that way."

 

I'm starting to think that over the course of my trip, as I got more comfortable with the car I just started driving it faster. That, plus the flatter terrain with fewer downhills (increase in total elevation going west) and a slight headwind reduced the opportunity for energy recapture.

Regenerative braking only recaptures some of the energy you previously spent to accelerate. If you're at the top of a hill, you used energy to get there. If you're slowing for traffic, or whatever, you used energy to get to that speed. The more you use regenerative braking, (the same applies to friction braking), is more energy is wasted. You only get back about half of what you spend (average). Ideally, we would never use regen or friction brakes, and just coast to a stop, but we need some to be civil and function in some effective way, so we waste some. If you are a "sporty" driver, don't expect much. BTW, the ELR is every bit as efficient as the Gen 1 Volt. The difference is the driver. Driving more "aggressively" is using more energy, and recapturing some of it during braking is proportionate to the aggressiveness.

 

For the iphone in addition to OBDlink app that come with the ODBlink MX+

you can get from the app store MyVOLTcontrol and the MyGreenVolt

both are good and show extra information - the add on features are low cost and some you may want.

---
I never drive with the ODB inserted - as there were a few problems in the early volt years.

if you go to the app stores there will be screen shots