Engaging Engine Braking (B) Function

Scan gauge doesn't agree with your assumptions.

 

You can only try to prevent the use of friction brakes by lesser pressure on the brake pedal, but ultimately whether to use regenerative brake or friction brake is decided by skid control ecu. Even if you don't allow the line to drop, friction brake may still be use, for e.g. when the wheels lose traction, the Skid Control ECU asks the HV ECU to stop providing regeneration and it modulates the pressure on the wheel cylinders to try to keep the wheels just on the verge of locking up. This is ABS.

Vincent

 

Still out of context... but you're right. In those extreme situations, the user wouldn't control the brakes.

 

It is not just those extreme situations, the skid control ecu is always in control. How much regen. or friction brakes depends on many other factors, e.g. SOC, battery temp., wheels traction, vehicle speed, MG2 torque, steering angle, shift position, etc, not just by brake pedal position alone.

If you 've SGII or Torque, you can monitor the Regenerative Brake Torque and see if you can keep it constant by keeping your brake pedal steady.

What can be controlled is your desire. You can decide not to use the friction brake by maintaining HSI above the line. Whether the skid control ecu fulfill your desire depends on many factors as stated above, which takes into consideration of safety first before efficicency.

I do advocate less friction brake use, but I do understand that I'm not in complete control. The car is designed for safety first then efficiency, not the other way round.

Vincent

 

I said that the friction brakes don't turn on unless you press it farther than the regen line...

 

This seems to have become an extraordinarily pedantic argument.

Within normal driving, if you have the HSI within the regen area without being at the full regen indication, the car will almost never use the friction brakes unless you are going so slowly that the regen braking is no longer effective.

Yes, there are exceptional circumstances where the car will bring in the friction brakes, but it's not the norm.

I did watch the ScanGauge yesterday (on different roads) and wasn't able to reproduce Agent J's hypothesis, however it was raining and I formed the view that it may have been necessary to go outside of what I considered safe driving, in which case I wouldn't have been overly surprised if the car would have wanted to intervene to maintain control. I will watch this again next time I have that situation in dry conditions. Also the roads I were on did not have corners as tight as the example that was given.

The example that was given were some tight downhill bends on what is technically a 60 km/h (37 mph) road, with a truck and bus speed limit of 30 km/h (19 mph). The suggested corning speed for all vehicles is 35 km/h (22 mph) though in Australia these recommended speeds tend to be ridiculously conservative, however the 45-50 km/h (28-31 mph) that was suggested for the test would probably be the right at the upper end of what I would ever do in dry conditions. Of course there are people who do all sorts of things through there. I'm not one of those people.

Spit Road & Medusa Street, Mosman - Google Maps

One of the problems with that example test is that the faster you are going, the less impact maximum regen braking has... while at the same time the faster you are going, the more energy you would need to control your speed on the descent and corners.

When you're familiar with the HSI, you know that it's easier and easier to bottom out the regen area the faster you are going. What I suspect would happen in this instance is that you would simply bottom out the HSI trying to do it and then, as expected, the friction brakes would have to come in. Of course VSC can be effective at any time if you push it too hard.

 

Is Torque a Pro or Lite version to monitor the Regenerative Brake Torque?

 

Either. You upload a custom PID. They can be found on numerous spots on this forum.