Braking

[ricschug]

I have not heard any mention of ABS brakes on the FUV although it should have them. What I was wondering is if the re-gen braking, since it most likely involves the computer, has any ABS capability? I would expect that, at least for the front wheels, acceleration and decelleration would have anti slip/spin features controlled by the computer. Can anyony from AMP shed some light?

[harriska2]

I know for sure it doesn't have antilock brakes. I think it should have been a minimum to be included - but what do I know.

[Odi]

The nature of regenerative braking cannot lock the wheels, so there is no anti lock needed. Traditional brakes when applied too hard can stop the wheel from spinning while there is still forward momentum, creating skids. On the other hand, regenerative braking is having the wheel turn the motor to generate electricity (think of those hand cranks that generate electricity to power flashlights or radios). So there is a maximum resistance that will not be enough to lock the wheel (instant deceleration to 0 would require infinite resistance, which also means the motor would be capable of instant acceleration).

That said, on slick surfaces, the resistance may be enough to have the wheel skid (the reverse of spinning out when accelerating). I saw in pictures from the 9.19.19 event that there is an electronic skid protection button, so that software would need to reduce acceleration or reduce regenerative braking when a skid is detected.

Luckily, the motors are on the front, so the tendency for all the weight to shift to the front will increase the friction between the road and the front tires. So even if the ESP doesn't work on regenerative braking, hopefully it is really hard to induce a skid with the regenerative brakes.

[harriska2]

The nature of regenerative braking cannot lock the wheels, so there is no anti lock needed. Traditional brakes when applied too hard can stop the wheel from spinning while there is still forward momentum, creating skids. On the other hand, regenerative braking is having the wheel turn the motor to generate electricity (think of those hand cranks that generate electricity to power flashlights or radios). So there is a maximum resistance that will not be enough to lock the wheel (instant deceleration to 0 would require infinite resistance, which also means the motor would be capable of instant acceleration).

That said, on slick surfaces, the resistance may be enough to have the wheel skid (the reverse of spinning out when accelerating). I saw in pictures from the 9.19.19 event that there is an electronic skid protection button, so that software would need to reduce acceleration or reduce regenerative braking when a skid is detected.

Luckily, the motors are on the front, so the tendency for all the weight to shift to the front will increase the friction between the road and the front tires. So even if the ESP doesn't work on regenerative braking, hopefully it is really hard to induce a skid with the regenerative brakes.

My problem is with people that assume they are in a 4 way stop but aren’t and I have to stomp on the brakes to quickly stop. The “oh shit” hydraulic brakes might get exciting in the rain.

[CreativeGuy]

Having driven Goldie for nearly 3000 miles, I’ll share my braking braking experience in an FUV. I found that the regen braking took care of over 95 % of my braking needs. I really only used the Hydraulic foot brake to keep the FUV stopped on a slope. The regen braking won’t keep the FUV “parked” if you are on a slope.
There were at least two instances where I had to make an emergency stop while driving fairly fast. I clamped down fully on the regen brake and the foot brake at the same time. I was almost shocked at how quickly Goldie came to a complete stop. So much so that were it not for the belt restraints, I felt like I could have gone through the windshield. Goldie stopped straight and true with no slip. Granted the road conditions were dry at the time. But I am very impressed at the stopping capability of the FUV.

[PAX]

Having driven Goldie for nearly 3000 miles, I’ll share my  braking braking experience in an FUV.  I found that the regen braking took care of over 95 % of my braking needs.  I really only used the Hydraulic foot brake to keep the FUV stopped on a slope.  The regen braking won’t keep the FUV “parked” if you are on a slope.
There were at least two instances where I had to make an emergency stop while driving fairly fast.  I clamped down fully on the regen brake and the foot brake at the same time.  I was almost shocked at how quickly Goldie came to a complete stop.  So much so that were it not for the belt restraints, I felt like I could have gone through the windshield.  Goldie stopped straight and true with no slip.  Granted the road conditions were dry at the time.  But I am very impressed at the stopping capability of the FUV.

I agree with CG,
 The hardest part of learning to drive the FUV was remembering the sometimes important use of the hydraulic brakes which are critical in two situations- after stopping on a slope or  hill and quick stop.  I did not get a chance to try hard braking on wet roads but I am willing to bet that it is easy to control but I am rather experienced in driving vehicles without anti skid protection. Not available in 1960-70-80.

[Sniffy]

The hardest part of learning to drive the FUV was remembering the sometimes important use of the hydraulic brakes which are critical in two situations- after stopping on a slope or  hill and quick stop.

Good to know.  Anyone coming from a two-wheeler will already have the muscle-memory for this.

[PAX]

Good to know.  Anyone coming from a two-wheeler will already have the muscle-memory for this.

I forgot to mention but I think that when the batteries are fully charged regen power is limited to protect the batteries from over charge.  I cannot remember has much on our Signature #6 but the battery  was choked down a bit and I suspect that on the new design it will be more prevalent.
It is very noticeable on our Leaf and a friend who has a Bolt says he has an option to set the charger to limit top end charge to allow regen if one lives on a hill.

[Odi]

I just struck through my misinformation above. The resistance doesn't need to be infinite to lock the wheels, I forgot that brake pads also don't have infinite friction. My thought process was the resistance from brakes happen with friction while the resistance from regen comes from generating electricity, but they both end up as resistance.

Locked wheels happen when the friction between the wheel and ground is no longer strong enough to keep the wheel spinning for a given brake / regen resistance. So yes, anti-lock regen could be useful. Unfortunately, that ESP button on the FUV is listed in the manual as "reserved for future implementation".

However, note that the Bolt doesn't have anti-lock regen either as I just read here https://www.chevybolt.org/threads/danger...ing.22658/

[CharonPDX]

One advantage is because regen is a physically separate control from friction brakes, you can use just regen, and it will be sort of a poor-man's ABS. As soon as the wheels lose traction, regeneration will cease, so the motors will "release" the wheels to spin freely again, which will act sort of anti-lock-like.