Using car scanner to monitor torque distribution between front and rear motors

[Rory]

I was interested in seeing how much relative torque was applied to the front motor. You can simply put together two gauges showing front and rear, but then you have to do some visual math to figure out the distribution, which isn't a good thing to be preoccupied with while driving. So I developed the following:

In car scanner, go to settings -> sensors -> +, which will get you a sensor labeled "New PID"
Edit the sensor as follows:

Name: Ratio Front to Total
Short Name: Ratio F/T
Decode scheme: Formula
Formula : 100*{Secondary Motor Torque from AC Source}/({Primary Motor Torque from AC Source}+{Secondary Motor Torque from AC Source})
Minimum: 0
Maximum: 100
Units: %

Add the sensor to your display. I use Gauge Indicator 2

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[Rory]

Some interesting findings:
If braking using regen only, the rear motor will do the braking until you are nearly stopped, at which point the negative torque on the front motor suddenly rises to take half the braking effort, after which the mechanical brakes are applied.

Low-speed acceleration involves both motors. Rarely see that at high speeds unless I really floor it.

 

[Mach-Lee]

Yeah I think they try to do balanced torque up to about 18 MPH, then the front motor goes to idle unless you are really flooring it. Rear does the vast majority of the work, front is just a small helper motor on non-GTs.

You should also look at traction slip (perhaps induced by going over bumps), I think that will instantly kick in the front motor.

 

[21st Century Pony]

Yeah I think they try to do balanced torque up to about 18 MPH, then the front motor goes to idle unless you are really flooring it. Rear does the vast majority of the work, front is just a small helper motor on non-GTs.

You should also look at traction slip (perhaps induced by going over bumps), I think that will instantly kick in the front motor.

This is similar to how the Audi E-Tron AWD splits the workload between its front and rear motors, afaik (Sonny Boy has a 2020 E-Tron).

 

[Kelvin]

Some interesting findings:
If braking using regen only, the rear motor will do the braking until you are nearly stopped, at which point the negative torque on the front motor suddenly rises to take half the braking effort, after which the mechanical brakes are applied.

Low-speed acceleration involves both motors. Rarely see that at high speeds unless I really floor it.

 

[Zirnius]

I know this is a bit of an older thread, but I'm wondering if you noticed any positive torque being applied to your front motor when you were looking into this.

I've just started playing around with the different gauges in CarScanner and I'm seeing positive 1.5kW or so of power draw at the front motor while the rear motor is regenerating power with a negative kW number.

I wonder if it's just a sensor issue or if there is something going on with the regenerative breaking. Or maybe it's supposed to do this to help with reducing the amount of weight shifting from one axle to the other, for stability reasons?

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