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2017 Mountain Mode - Some Observations

1370 Views 12 Replies 11 Participants Last post by  zeldar
2018 Volt LT 97,000 miles.

Just FYI:

I am on a cross country trip through the rockies, much of it off interstates. This is my first time mountain driving in a Volt though I am an experienced mountain driver. I started in Wisconsin. Here are a few things I observed.

I drove up a 6% incline at 70mph for 2.5 miles in Normal Mode and the battery indicated miles dropped from 37 to 16 miles in that distance. Those indicated battery miles ticked down remarkably quickly. I was wondering how hot the electric motors must have gotten drawing all that power.

I drove up another 6% incline of 3 miles in Hold Mode (16 battery miles left). Nearing the top the engine seemed like it was screaming at a very high rpm. The coolant temp was 217 degrees at the top. The car made it with no apparent reduction in performance, but I think I was at the edge of what that car is capable of. I understand physics pretty well and that engine had to be working pretty hard to lift all that weight at that speed. The battery charges nicely downhill. During the subsequent descent the battery mileage increased to 29 miles, but I don't know how far it was.

Those were the only 2 notable up slopes on this trip so far (Santa Fe to Phoenix), but the next mountain driving leg will be up towards Flagstaff then Moab UT. I will use Mountain Mode for the remainder of the trip in mountainess areas. I am be curious to see how well it works. I am also curious to see what the battery charge level (miles left indicated) will be on the "other side" if I start mountain mode with a near full battery of about 40 miles indicated. Will it return to 40 after each descent?

Downhill driving is a breeze in Low. I'm don't think I engaged the physical brakes at all. I'm pretty sure all of the downhill speed control was done via regen. But I don't know for sure.

Interesting trip. 9 days left of 15. After Moab, it's Rock Springs WY then Denver. Another learning experience.
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Here's the writeup I did on my experiences with not needing Mountain Mode.

This isn’t really true, especially on a gen-2. The ICE is quite often mechanically driving the wheels, in addition to producing electricity.
Even the Gen 1 Volt has a mode where the ICE is directly connected to the drive shaft. It's not used nearly as often as in the Gen 2, but thermodynamics is very clear - when burning gas, use what is needed to propel the car and only convert the rest to electricity. Thermodynamics is very clear that you will have a loss during the conversion to electricity.
I have a 2017 Volt. I have the MyGreenVolt app. Today I was driving the Interstate on Cruise at 70MPH on ICE power (Hold mode). I had the MyGreenVolt app RPM / tachometer Dashboard gauge showing me ICE RPMs I don't believe there was direct connection of Ice to wheels because the ICE RPMs were constantly fluctuating depending on the grade of the Interstate.
Don't forget the ICE is also used to maintain the battery buffer when in Hold mode. As such, RPM fluctuations are normal as the car determines the amount of power needed to maintain this buffer. Remember, no road is flat, so the down hills will require lower RPM to maintain the same speed (it's not a manual transmission) and the uphills will require a higher RPM. The Volt's planetary gear set is a transmission and the ICE and both electric motors all connect to it. In the gen 2 Volt more of the power from the ICE is directly transmitted to the drive shaft from this transmission.
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