Regenerative braking

[kabalah70]

Anyone else notice that the regenerative braking lightens up signifcantly at 10 mph? Most noticeable in Hill 2. I am sure that it is not effective at this point. Nice to know though, as that would be the point you need to actually depress the brake pedal to continue a progressively slowly stop.

[siliconkiwi]

Yes, I have experienced it too (but didn't make the connection until your mentioned it). Makes sense to me, if it really is a "Hill mode" not a "regenerative mode".

[Fabulist]

(01-30-2012 03:38 PM)siliconkiwi Wrote:  Yes, I have experienced it too (but didn't make the connection until your mentioned it). Makes sense to me, if it really is a "Hill mode" not a "regenerative mode".

In the Edmunds walk around of the suspension system, they mentioned that only the first 0.25G of braking deceleration is soaked up by the regen system and the friction brakes kick in after that. This may be a manifestation of that limit. Ultimately, you cannot stop the car by regen alone and you have to waste a little forward momentum by converting it into heat.

-- Fab.

[kabalah70]

As long as you brake soon enough you should be able to keep the braking below 0.25 Gs. Although, the other night, being a fool in heavy stop and go traffic, I engaged 100% braking as evidenced by the ABS kicking in. Needless to say, my heart was pounding for a few minutes afterward at the though of almost smashing up my brand new car and either having it sit in the garage for months until parts came in or drive it around and show off what acomplete tool I was. Whew!

[bigdaddyo811]

1. Can someone outline the difference between Hill 1 and Hill2

2. What is the purpose of Hill 1 and Hill 2 when if you are coming to a stop and you are going to hit the brakes or do hit the brakes the amount of regen is much more than Hill 1 and Hill 2

3. Is there any damage done driving in Hill mode? Today I clicked into Hill 1 and Hill 2 and thought I had gone into D but I didnt. So I drove for a mile in Hill 2 it seemed. I wish the car would automatically click into D once you hit the gas pedal as there is no reason to be in hill ever if you are depressing the gas pedal right?

[siliconkiwi]

Hill turns on regen ONCE YOU PULL YOUR FOOT OFF THE ACCELERATOR. If you are accelerating, I believe there is no difference between D, H1 and H2. (From what i can tell of previous comments) most of us drive in hill 1 or hill 2 most of the time. Think of it as engine braking. I find it useful in stop and go highway traffic.

-k

[Karma31]

(02-04-2012 02:39 PM)siliconkiwi Wrote:  Hill turns on regen ONCE YOU PULL YOUR FOOT OFF THE ACCELERATOR. If you are accelerating, I believe there is no difference between D, H1 and H2. (From what i can tell of previous comments) most of us drive in hill 1 or hill 2 most of the time. Think of it as engine braking. I find it useful in stop and go highway traffic.

-k

Hill 2 really makes stop and go traffic less annoying IMHO

[LonePalmBJ]

(02-04-2012 02:14 PM)bigdaddyo811 Wrote:  1. Can someone outline the difference between Hill 1 and Hill2

2. What is the purpose of Hill 1 and Hill 2 when if you are coming to a stop and you are going to hit the brakes or do hit the brakes the amount of regen is much more than Hill 1 and Hill 2

3. Is there any damage done driving in Hill mode? Today I clicked into Hill 1 and Hill 2 and thought I had gone into D but I didnt. So I drove for a mile in Hill 2 it seemed. I wish the car would automatically click into D once you hit the gas pedal as there is no reason to be in hill ever if you are depressing the gas pedal right?

As I understand it:

Both hill modes function similarly - while the car is decelerating the motor-generators capture some of that momentum to spin up and generate electicity and store it back in the battery system. It's a way of converting the forward motion of the car to electricity instead of heat (which is what happens using friction braking). Both hill modes engage when you let off the gas - they do not require you to step on the brake pedal. The difference between Hill 1 and Hill 2 is simply the level of engagement and the amount of forward progress converted to electricity. Just like the compression braking you'll experience letting off the throttle in a manual transmission car, you'll feel the deceleration from the Hill modes. In fact, Hill 2 for me feels a lot like letting off the gas in 3rd or 4th gear in my old Audi TT.

It's called Hill mode because its primary use is to capture electricity while descending grades. Instead of using the brakes to slow the car or maintain a constant speed while going downhill, the Hill modes will perform the same task but convert gravity to electricity. It allows you to get some regenerated power for "free" (ignoring the fact that you probably spent even more electricity to get to the top of the hill in the first place)

There's no need to disengage Hill mode. Even on relatively flat surfaces the tradeoff between forward movement and electric is still available to you. If you use Hill mode frequently not only will you get some free power back into the system, but you'll reduce the amount of wear on the friction brakes, and the amount of brake dust on the pretty circuit blade wheels.

It's a matter of personal preference. If you are used to driving an automatic, where letting off the gas doesn't produce a pronounced deceleration, then hill mode may feel strange. If you're used to driving a stick where letting off the gas or downshifting provides a noticeable deceleration through compression braking, you might like Hill 1 or Hill 2. My wife, who drives a manual shift Miata, thought Hill 2 felt natural.

Regardless of the mode selected (D, H1 or H2), there is regenerative braking that happens when you step on the brake pedal - the first .25Gs of deceleration is accomplished via regen before the calipers clamp down.

The system is pretty smart too - the Hill modes and brake regen disengage if the battery if full and there's nowhere to store any generated electricity.

I beleive this is all correct, but if anyone know something I don't please enlighten me!

Brent

[kabalah70]

Sounds like you have basically covered it. It is nice to see that Fisker has confused someone with it and it is all the more reason I believe that they should do away with calling Hill mode a driving mode instead of a regenerative braking mode. See my proposed software change poll for more explanation.

http://fiskerbuzz.com/forums/Thread-Desi...anges-Poll

[rex]

Is there anyway to turn on hill2 as my default? I have to turn it on each time when I start or switch to sport to stealth, and I sometimes forget, until I take my foot off the gas, expecting to slow down, only to go, "oops, still in d"