phidauex
Well-Known Member
- First Name
- Sam
- Joined
- Dec 8, 2020
- Threads
- 15
- Messages
- 840
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- 1,545
- Location
- Colorado
- Vehicles
- 2021 MachE 4EX, 2006 Prius, 1997 Tacoma
- Occupation
- Renewable Energy Engineer
- Thread starter
- #1
In my theme of trying to answer common questions about MachE behavior with actual data, here are the results of an hour long drive up the Colorado front range, with a few interesting data points logged.
In particular, I was watching Brake Pressure, which tells us the pressure at the brake master cylinder. The pressure is 0 bar when the hydraulic brakes are not engaged, but goes up to 5+ bar as the hydraulic brakes engage. This lets us tell exactly when the system decides to apply friction braking, because it doesn't change with the pedal position, it changes with the actual pad engagement.
What I can now say with confidence is that in 1 PD mode, in Whisper, Engage or Unbridled, the MachE will not apply friction brakes at all (not including collision avoidance). It simply doesn't, even when coming to a complete stop. If you look at my datalog, I applied the brakes before leaving, just to show the data spiking, and I applied them once at a stoplight where I pushed the brake pedal firmly. All the rest of the driving, through three cities, was just in Unbridled 1PD, in quite a bit of stop and go. I let off the pedal entirely many times, and several times applied the brake pedal directly, and even with moderate pressure on the brake pedal the friction brakes never engaged, except for the one time when I was already at a complete stop. I made no attempt to hypermile - it was too busy to drive very fast, but I just drove it like a normal car and didn't think about optimizing regen or anything.
What does this mean by the numbers? The maximum deceleration achieved in 1PD without touching the brake pedal is 0.2g. Pressing the brake pedal got me to 0.3g without the friction brakes. Maximum regen power was 91kW. I'll take some more logs later where I actually apply more and more brake pedal to see at what deceleration the brakes will actually come on.
Over 50 miles, the system regenerated about 22% of the total energy consumed, which is pretty impressive. My mi/kWh would have been about 2.29 mi/kwh, but regeneration brought it back up to 2.92 mi/kwh. (Note that these values are fairly coarse because I didn't measure the Energy Remaining field directly, but instead am integrating over 560ms datapoints, with some error). More important is the relative percentages.
I was having trouble logging the battery temperature points (something is acting up in CarScanner), but I was able to spot check them and was seeing favorable values around 30C.
Attached is the full datalog for your amusement, and some stats from the drive below.
In particular, I was watching Brake Pressure, which tells us the pressure at the brake master cylinder. The pressure is 0 bar when the hydraulic brakes are not engaged, but goes up to 5+ bar as the hydraulic brakes engage. This lets us tell exactly when the system decides to apply friction braking, because it doesn't change with the pedal position, it changes with the actual pad engagement.
What I can now say with confidence is that in 1 PD mode, in Whisper, Engage or Unbridled, the MachE will not apply friction brakes at all (not including collision avoidance). It simply doesn't, even when coming to a complete stop. If you look at my datalog, I applied the brakes before leaving, just to show the data spiking, and I applied them once at a stoplight where I pushed the brake pedal firmly. All the rest of the driving, through three cities, was just in Unbridled 1PD, in quite a bit of stop and go. I let off the pedal entirely many times, and several times applied the brake pedal directly, and even with moderate pressure on the brake pedal the friction brakes never engaged, except for the one time when I was already at a complete stop. I made no attempt to hypermile - it was too busy to drive very fast, but I just drove it like a normal car and didn't think about optimizing regen or anything.
What does this mean by the numbers? The maximum deceleration achieved in 1PD without touching the brake pedal is 0.2g. Pressing the brake pedal got me to 0.3g without the friction brakes. Maximum regen power was 91kW. I'll take some more logs later where I actually apply more and more brake pedal to see at what deceleration the brakes will actually come on.
Over 50 miles, the system regenerated about 22% of the total energy consumed, which is pretty impressive. My mi/kWh would have been about 2.29 mi/kwh, but regeneration brought it back up to 2.92 mi/kwh. (Note that these values are fairly coarse because I didn't measure the Energy Remaining field directly, but instead am integrating over 560ms datapoints, with some error). More important is the relative percentages.
I was having trouble logging the battery temperature points (something is acting up in CarScanner), but I was able to spot check them and was seeing favorable values around 30C.
Attached is the full datalog for your amusement, and some stats from the drive below.
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