Volt OBD2 Torque

Efficiency - Wikipedia, the free encyclopedia

 

You are right this is overall efficiency of moving from one point to another, but the biggest resistance to overcome here is rolling and air resistance, meaning that the biggest factor of efficiency would be speed. Of course at some point the speed is so slow that parasitic draw from the car systems is too big I'm guessing this number would be around 15-20 mph, anything higher would mean less efficiency.

I still don't know how you would use this PID to alter driving technique? You would get a bigger gain just by looking at your speed and braking as little as possible.

What you would need to alter the driving technique is el. motor output (kW) / battery drain (kW), now this would give you an idea where and how to accelerate.

 

the parasitic draw seems to be about 300W, but the heater can significantly change that. the sweet spot for kWh/mile seems to be 35-45 mph but if we assign some value to time, which is why we drive versus walk (and fly vs drive), the sweet spot may move up to 65 mph for longer trips.

instant Wh/km can be used to understand the impacts of hard acceleration, going over a hill versus around, hard stops, coasting, etc...

Prius drivers have been using instant MPG displays to learn driving techniques, but some of those techniques don't seem to apply in EV mode.

The Volt has several significant EV modes as well, Normal, Low and Sport. The "Low" mode is mislabeled in my opinion and operates like the Tesla's "one pedal driving" where letting off the accelerator pedal brakes the vehicle using heavier regeneration. Some driving conditions seem to benefit more from this mode, like city start/stop.

The instant Wh/km is too instant, imo. I think it might need to be normalized for some short period, like 10 seconds. I don't think we can achieve this in torque without an add-in though, or discovering another PID where the ECU does the normalization.

I have a lazy quest to assign benchmark kWh values to specific road segments, for each direction, and then score each trip against the benchmark.

today I use this tool for the benchmark.

www.jurassictest.ch/GR/

 

Thanks for doing this. I have a geeky friend with a volt, I will point him to this.

 

The forumula for Driving Efficiency is [Battery Voltage]*[Battery Current]/[Speed]. Unfortunately, I can't make a formula which would update the numbers in 10 second intervals and average the last 10 seconds.

However, the last video was made when the traffic density was quite high and speeds were very uneven, so the result is far from perfect. When weather gets warmer I will find a long flat road with no traffic, probably late at night and do test at various speeds (20, 25, 30, 35, 40, 45, 50, 55, 65 km/h) with CC on. This should give more consistent result, at which speed, including parasitic losses, is driving most efficient. Now that I think of it, I would have to do the driving early morning, probably Sunday morning, so that I would be able to drive without headlights, only with DRLs, which would be the best scenario to represent driving during the day.