Premise: I personally love the "one pedal" driving that regenerative braking offers. Having had my car for 2 months & ~5,300 miles, with about 2,000 of those miles being road trips, I'm of the opinion that an option for having a mode that allows for greater than 60KW of "deceleration force" would be useful. While the current regen mode serves well for many situations, there are three scenarios where I think I'd find more useful:
1- High Speed Stop and Go Driving: While typical stop and go driving on city streets where the speed limits are in the 35-45MPH range are reasonably well served by the current regen mode, when things start getting congested on the highway (I-95, I'm looking at you!), it's not uncommon to be travelling at 60-80MPH for some time, only to have traffic grind to a halt, and then start back up again. Rinse & repeat.
I found myself having to leave so much room between the car in front of me to allow the regen to be effective that I'd get lane jumpers cutting in front of me. A bit more regen available would keep me from having to ride the brakes as much. This is a "common, but not daily" issue for me.
2- Loaded Driving: On two of our road trips, we had 4 of us in the car with bags of "road trip stuff" (laptops, tablets, books, snacks, drinks, etc...), luggage in the trunk, extra stuff in the frunk (coolers, etc...). It's easy to add another 20-25% of the weight of the car for a vacation trip. With the extra weight, I could definitely feel the effect on the regen... again causing me to have to leave too much room in front of me in highway traffic to be as useful as I'd like. Or I'd have to start slowing down awfully early on city streets approaching intersections. This is only an "occasional" issue for me.
3- Some Intersection/Light Combinations: I find that for many intersections, the time to regen decelerate when the light turns yellow is often greater than the time to cover the distance to the intersection in 45MPH zones. Or if there's any slight downhill grade leading to an intersection it hard to bleed off speed quickly enough if you are generally matching the flow of traffic. There are several intersections in my daily commute that are like this, thus it's a "daily issue" for me.
Considerations:
1- I don't know if the hardware in the car is even capable of this. I've heard that other vehicles are capable of "1C regen", specifically one of the Fisker threads here mentioned it had greater regen capability. So it may be possible with the S, and if so might be changed via firmware
2- Greater regen might be "too abrupt" for some folks. This might be true if some people aren't used to modulating the accelerator pedal. I've already gotten in habit of not simply "letting off" the pedal unless I immediately need max regen. Ditto for cancelling cruise control, I depress the pedal slightly to even out the transition.
Adding a larger range (to 80KW or perhaps even more) simply means a greater range of regen I can modulate. I also suggest making it an option in the car settings ("Max Regen" vs "Standard Regen") for those who don't want it at all , or all the time.
3- There might be other concerns, such as rear tires losing traction too easily, etc... but it seems to me that if the traction control in the car can manage 320KW of forward acceleration, than 80KW of deceleration force shouldn't be too difficult. Clearly the TC is already active on deceleration, as if you hit a slick spot it will cancel regen to avoid the car getting squirrely.
4- Linearity... as acceleration force is non-linear with power applied, I assume deceleration is the same. As such, to really add materially to the braking force, only allowing 80KW might not do much. It may be that 100 or even 120KW is the correct number.
Suggestion: Keep the current 60KW regen as "Standard Regen". Add a "Max Regen" option that allows 80KW (or 100, or 120...) of regenerative braking to be applied. Link this to the driver profile so it doesn't surprise my wife.
Thoughts?
1- High Speed Stop and Go Driving: While typical stop and go driving on city streets where the speed limits are in the 35-45MPH range are reasonably well served by the current regen mode, when things start getting congested on the highway (I-95, I'm looking at you!), it's not uncommon to be travelling at 60-80MPH for some time, only to have traffic grind to a halt, and then start back up again. Rinse & repeat.
I found myself having to leave so much room between the car in front of me to allow the regen to be effective that I'd get lane jumpers cutting in front of me. A bit more regen available would keep me from having to ride the brakes as much. This is a "common, but not daily" issue for me.
2- Loaded Driving: On two of our road trips, we had 4 of us in the car with bags of "road trip stuff" (laptops, tablets, books, snacks, drinks, etc...), luggage in the trunk, extra stuff in the frunk (coolers, etc...). It's easy to add another 20-25% of the weight of the car for a vacation trip. With the extra weight, I could definitely feel the effect on the regen... again causing me to have to leave too much room in front of me in highway traffic to be as useful as I'd like. Or I'd have to start slowing down awfully early on city streets approaching intersections. This is only an "occasional" issue for me.
3- Some Intersection/Light Combinations: I find that for many intersections, the time to regen decelerate when the light turns yellow is often greater than the time to cover the distance to the intersection in 45MPH zones. Or if there's any slight downhill grade leading to an intersection it hard to bleed off speed quickly enough if you are generally matching the flow of traffic. There are several intersections in my daily commute that are like this, thus it's a "daily issue" for me.
Considerations:
1- I don't know if the hardware in the car is even capable of this. I've heard that other vehicles are capable of "1C regen", specifically one of the Fisker threads here mentioned it had greater regen capability. So it may be possible with the S, and if so might be changed via firmware
2- Greater regen might be "too abrupt" for some folks. This might be true if some people aren't used to modulating the accelerator pedal. I've already gotten in habit of not simply "letting off" the pedal unless I immediately need max regen. Ditto for cancelling cruise control, I depress the pedal slightly to even out the transition.
Adding a larger range (to 80KW or perhaps even more) simply means a greater range of regen I can modulate. I also suggest making it an option in the car settings ("Max Regen" vs "Standard Regen") for those who don't want it at all , or all the time.
3- There might be other concerns, such as rear tires losing traction too easily, etc... but it seems to me that if the traction control in the car can manage 320KW of forward acceleration, than 80KW of deceleration force shouldn't be too difficult. Clearly the TC is already active on deceleration, as if you hit a slick spot it will cancel regen to avoid the car getting squirrely.
4- Linearity... as acceleration force is non-linear with power applied, I assume deceleration is the same. As such, to really add materially to the braking force, only allowing 80KW might not do much. It may be that 100 or even 120KW is the correct number.
Suggestion: Keep the current 60KW regen as "Standard Regen". Add a "Max Regen" option that allows 80KW (or 100, or 120...) of regenerative braking to be applied. Link this to the driver profile so it doesn't surprise my wife.
Thoughts?
Last edited:
