Different braking implementations

OK, maybe I am a non-friction-braking junkie.

Today, I had a discussion with a friend who owns a Tesla model S. The single motor type, but with the complete performance pack. As we started to talk about braking, we figured the S’s stategy is quite different than on the Zoe and is actually closer to the Fluence and Kangoo. In simple terms, on the S, touching the braking pedal does friction braking, period. Regeneration is applied through not, or barely touching the accelerator. He calls this “one foot driving”.

He also told me the “average” tesla driver doesn’t do any aiming-braking. With that I mean unpowered coasting, letting the motor basically run free. It seems to be popular with Fluence hyperdrivers to avoid the regen-use cycle.  I have to assume this is because hyperdriving is less of an issue with a 80kW battery.

The regenerative braking strategy itself is different too. The Zoe seems to aim at fixed torque, mimicking a traditional car. It is transparent to the driver if that torque is generated through regeneration or friction braking. The S seems to aim at a fixed regeneration power level (up to 60kW, which is lower than the Zoe per kg). As I explained in the previous post, that means increasing torque as the speed bleeds off. When the car reaches roughly 50km/h it seems to switch to constant torque, probably as otherwise the braking would get too brisk and uncomfortable. It is an interesting approach (irrespective to whether it is controlled through a braking pedal or not) as it is the behaviour I am trying to mimic through following the blue bar in the driving screen.

Posted in Car
2 comments on “Different braking implementations
  1. PieterZoe says:

    Please don’t feel lonely as there will be many non-friction-breaking junkies in the world of electric driving : ) At least I am one of them.

    And I do like one-foot driving a lot! It is quite feasible with the Zoe. When SOC is below 80% and the outside temperature is modest one barely needs to move the foot to the other pedal during driving (assuming no red traffic lights).

    Is there a way to program the Zoe to use more of the available regenerative breaking torque when lifting the accelerator? and if so, could we also program the Zoe to light up the breaking lights when a certain level of electric breaking torque is applied?

    • Jeroen Meijer says:

      I fully agree and the very best strategy to avoid friction breaking is to not touch the braking pedal at all. Having said that, the new aiming bar really does help me when I do need to brake.

      What you propose is reprogramming the EVC and we are really not into that. Actually, most of the team members made a sort of vow not to write anything. It is a bit dangerous. One fiddled a bit and almost screwed up the ABS. luckily it recovered after 10 or so power cycles. Phew. What you are requesting is 100% possible, including the braking lights. We just don’t know how. Land me a job at Renault France and I will figure it 😉

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