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2017 Mountain Mode - Some Observations

1378 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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Electrical motors are typically very efficient. If you were using 80 kW to climb the pass, only a small percentage was lost to heat. A comparable car needing to generate 100 hP to climb the same hill would be generating nearly 200hP in thermal losses.

I don't suspect the motors (inside the transmission) were overly hot...
Even 90% efficient motors would have to deal with 8-10kW of sustained heat here, which is not nothing. But the transaxle has its own cooling loop / radiator, and is designed for this operation, so yes I'm sure the temperature was fine.
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