Oct 5, 2011
Nik A snippet from the TTAC contributor's write-up of the Model S beta factory tour. For those who have strong opinions on the subject, this might be of interest.
http://www.thetruthaboutcars.com/2011/10/tesla-model-s-customer-blog-beta-under-the-bright-lights/#more-413446
Way to go with the customer feedback, but I do hope Elon isn't seeing himself as some form of replacement Steve Jobs.�
Oct 5, 2011
AnOutsider Why Steve jobs? Because he responded to the email? I +1 adjustable regen though.�
Oct 5, 2011
efusco That's good news. But as a "Prius Expert" the information in that statement about the Prius applying the friction brakes is completely false. It was true on the first gen prius, but since late 2003 the 2nd and 3rd gen Prius do not apply the friction brakes at all until you get below 7mph or in abrupt/emergency braking situations.�
Oct 5, 2011
Citizen-T Is it just me or are the tail lights in the first video in that article (around 20s) different from the Betas we saw on the tracks? They look more Roadster like.�
Oct 5, 2011
Nik That, and the apparent making of policy on the hoof. Do that too often and one day you come a cropper.�
Oct 5, 2011
vfx Same as the ones in the charge port door picks?�
Oct 5, 2011
TEG Yes, there was that one partially finished chassis on the factory floor with the one charge port door people could touch (although no socket behind it) and those big round (LED?) tail light fixtures. My assumption is that they are not anything that would ever see production, and were maybe just a test fixture to make sure the wiring harness could activate the rear lights. They looked like something you could buy at an auto parts store to go on a trailer:
Or maybe those are just buried under the light reflector box that changes the shape of what you see?
�
Oct 5, 2011
Doug_G Having the ability to temporarily disable regen would be wonderful for those rare times you take the car on a track. You don't want it getting in the way of cornering.
For street driving however I'd want as much regen as they can muster.�
Oct 6, 2011
vfx This is GREAT news.
Now to get it where it can be adjusted quickly while driving. The AC Propulsion E Box has a 4" mechanical slider on the dash. As i have said before I would love a dedicated steering wheel stalk to adjust regen radidly when approaching a traffic jam (more) driving highways (less) heading into the canyons (more) and general hypermiling (less).
I don't think Fanz reads these boards but if there is an engineer reading this please pass it on the design team as well.
�
May 22, 2012
NigelM Here you go.....
�
May 22, 2012
AnOutsider And the pic they posted with it:
Seems to only show 2 settings though
As an aside, is this the first official screengrab of a Model S screen? And will we have screenshotting capabilities?�
May 22, 2012
onlinespending hopefully they allow you change the suspension a bit more easily than clicking through the touchscreen menus. I can see there being times when you need to adjust it rather quickly as you approach a drive-way or speed bump as an example.�
May 22, 2012
NigelM Dude, slow down. That's what speed bumps are for......�
May 22, 2012
Robert.Boston I really want to know what the "Jack" button does.�
May 22, 2012
AnOutsider Probably the highest setting to allow you to easily get under it? If so though, I guess those without the air suspension are gonna have it harder.
*edit* or maybe it disables the air suspension and rigidly locks it in place so it's not dangling as you jack the car up�
May 22, 2012
Zorba I think it probably is a screenshot from a computer screen.�
May 22, 2012
goyogi Sure, if you know where you are going but often if you don't know the terrain and you for example have to turn into a driveway that is steep you'd want to be able to adjust it quickly instead of annoying all the people behind you. Hopefully they'll have voice control. "KITT (or HAL), raise the suspension". Or "Go go gadget suspension"�
May 22, 2012
NEWDL The screen simulations are run on computers at Tesla. I am sure this came from one of those setups. Unless Tesla leaks how to screen shot, I doubt it will be a feature at first if ever.
Happy to see adjustable Regen. I hope for more adjustment...�
May 22, 2012
Robert.Boston I believe that changing the suspension will require two 'button' pushes: Controls/RegenLevel. It may require a third (an intermediate Driving push) if your Controls dialog isn't on Driving already. But a voice command ("Tessie, suspension high") may be quicker.�
May 22, 2012
Lloyd Yes, the blog posts says that 'some will like a little more and some will like a little less.' That is not available with just two buttons. I would like to see a slider with Aggressive regen on one side, and less regen on the other.�
May 22, 2012
SoCalGuy That's what the Karma has - three regen braking modes that are accessible via a paddle shifter behind the steering wheel (D is minimal, Hill 1 is moderate and Hill 2 is aggressive). It's super fun to use! Contributes to the experience/theater of driving the car.�
May 22, 2012
ElSupreme I want 'panic stop' powered regen.
But really I will have it set at maximum whenever I drive.�
May 22, 2012
Doug_G Obviously it lifts one wheel off the ground for you. :biggrin:�
May 22, 2012
gg_got_a_tesla Yeah, how about that "Bounce" option?!
How to Bounce a Car | eHow.com�
May 22, 2012
vfx Agreed on the slider. Sadly it's just two settings. The Fisker has three on the tree. Now that is awesome! (and kinda retro)�
May 22, 2012
daniel I agree that driver-adjustable regen is a good idea. That said, I've gotten used to, and mostly like, the hard regen on my Roadster. For freeway driving, though, I think it would be easier without it. That makes adjustable a good idea.�
May 22, 2012
tdelta1000 Another want from the consumer turned into a reality by Tesla Motors. Way to go Tesla Motors!!!�
May 22, 2012
dsm363 I agree. This really makes me think they are working on some sort of solution to solve people's concerns about storage pockets in the car/center console.�
May 22, 2012
Doug_G Personally, I would only ever set it to minimum or maximum. Maximum 99% of the time, and minimum if I wanted to try it out on a track.�
May 22, 2012
AnOutsider Wouldn't higher regen be an asset on the track? Less use of the brakes == less heat generated. I think 3 stages would be best (normal, high, low), but I've never driven a Roadster and clearly not a Model S, so maybe what they have works.�
May 22, 2012
JRod0802 Not from what I've read. The regen is only on the rear wheels, which screws up the dynamics of the car if you let your foot off the gas while going around a corner. I think it makes it easier for the car to spin out.
You can try to regulate it with your foot to be perfectly in the middle "coast" spot, but it'd be easier to just turn it off.�
May 22, 2012
Robert.Boston My guess -- not even an educated guess -- is that each regen setting requires a number of sub-systems to be carefully coordinated. Therefore, a slider doesn't work well. Also therefore, adding variations should be something that future software updates can accomplish.�
May 22, 2012
Doug_G No. Before entering a corner you need to brake hard to transfer weight onto the front wheels, which aids the turn-in. During maximum turning you need to have neutral acceleration so you don't exceed the grip capabilities of the tire. Once you're passing the apex and unwinding the steering you're getting back onto the accelerator. To do a corner properly requires some finesse, and the regen definitely gets in the way. When you lift off the brake it tends to alter the weight transfer away from the front wheels, and that not only reduces turn-in but also unsettles the car (i.e. the suspension).
I've mostly done autocross with the Roadster, which is a bit more forgiving, but I've done a CASC-OR race school with it, and it was a bit of a problem. My instructor was very experienced and even he had some trouble adapting. We'd have to move very quickly from the brake to the accelerator, yet press only very slightly to keep the acceleration neutral. It's hard to get it just right, and even then I don't think the end result is ideal.
You also have a risk of snap oversteer if the regen kicks in while you're turning. You can do that in well balanced RWD gas car, too, but the regen is rather more powerful. Last year during an autocross event I was distracted by hitting a cone, and I lifted off for a split second. The result was a spectacular spin just before the stop box - right in front of the spectators. :redface:�
May 22, 2012
vfx If the max would be the equivalent of slamming on the brakes and snapping your neck then I doubt that is the case (try driving a MiniE for example). No, an adjustable slider with say, 8 or ten settings is ideal.�
May 22, 2012
William13 I don't know how to race a car but at least in the past race cars were manual transmision. The regeneration is probably very similar to that pull of an engine if the clutch is not depressed. The low setting for regen might be very much like a manual transmission.�
May 22, 2012
Doug_G I don't know about the Model S, but the regen on a Roadster is much stronger than a manual transmission.�
May 22, 2012
spatterso911 How will weight transfer be affected with the low CoG? Will braking have the same effect on weight transfer? Lots to consider here, and I don't have a real reference point. Even open wheel racers have the majority of their weight above the axles.�
May 22, 2012
Doug_G Clearly it will reduce the weight transfer. In most respects this will be an improvement. You have more traction overall if the weight is balanced on all four wheels.
It will have some effects that some people consider a minus; for example, less weight transfer to the front might mean more understeer at turn-in. But overall there will be more traction through a corner. Who knows, the Model S might turn out to be an excellent track car.�
May 22, 2012
spatterso911 I remember reading somewhere that the rear wheels will have better performance with turning as well, as a result of the weight being between the axles. Does anyone know more about that?�
May 22, 2012
goyogi The next roadster if equipped with awd and with independently adjustable regen in the front and back would help.�
May 23, 2012
daniel The other day, some guy (he looked kind of scruffy, so he might have been an auto mechanic or a homeless guy, for all I know) told me about some gal giving him a ride in a fancy car (I forget the brand/model) that has all-wheel steering! He said she could take a sharp corner at 60 mph. Maybe he was exaggerating, but the point was that supposedly all-wheel steering gives much better handling in turns. When I consider the possible consequences, I've decided not to take my Roadster to the track to try to find out what it could do. I love driving electric, and I enjoy flooring it up to the speed limit, and I like the way it takes curvy roads. But I'm not a race-car driver.�
May 23, 2012
frequencydip Regen causes heat in the motor, so either heat the brakes or heat the motor, its beter to heat the brakes as thats what they are designed to dissipate heat more than the motor is.�
May 23, 2012
ElSupreme Traditional brakes convert roughly 100% of your kinetic (movment) energy to heat.
Regen brakes convert about 80-95% of your kinetic energy into chemical stored energy in the battery. The rest is dissipated into heat. Which is easily dissipated by the motor and battery cooling system.
Regen produces much less heat.�
May 23, 2012
frequencydip Best case scenario regen converts 80%, and the remaining 20-40% is a signifiant amount of heat. I have overheated the roadsters motor on multiple occasions and regen is a signifiant contributor to that. So if there was a way to turn it off at the track I would.�
May 23, 2012
Doug_G I've also had a power limit because of a hot motor. It is the weak point for performance driving in the Roadster.
The Model S motor is, of course, liquid cooled.�
May 23, 2012
DaveVa Motor in the S is water cooled, while brakes are air cooled. I think it would really need to be something that is tested and determinded on the track. When racing, it was amazing how many things were changed to adjust for the characteristics of a specific track. Everything from tires, wheel camber, cam timing etc... I wouldn't be surprised if it was race/track/driver specific thing.�
May 23, 2012
vfx Adding cooling to drivetrains of racecars is normal. Transmission coolers, beefy oil and water cooling and vented brakes is standard. Doing the same of an electric motor, gearbox, electronics and brakes is reasonable.�
May 23, 2012
doug Wow, you guys are way of topic and I'm not even sure what to do with this thread.
Anyhow, to answer the question about how to control the Roadster's regen on the track, the answer is to drive two footed. You modulate your right foot to cancel out regen while you brake with your left foot. It's been done.�
May 23, 2012
BriansTesla From my experience hypermiling, I would like the Model S to coast without regen but to maximize regen when the brakes are applied. This should give the best efficiency. I'm sure the cruise control should do this well on the S.�
May 23, 2012
vfx Tesla has never put regen on the brakes. They prefer single foot driving. Cruise control on the Roadster uses regen on downhill. It's amazingly perfect.�
May 23, 2012
BriansTesla Seriously, no regen on the brakes? That's a lot of energy going to waste. I am averaging 10-20% regen in town driving a plug-in conversion.�
May 23, 2012
Doug_G You misunderstand. No regen on the brake pedal. The regen is on the accelerator pedal. Full lift off = maximum regeneration.�
May 23, 2012
JRod0802 Instead of building the regen into the break pedal, they built it into letting off the gas pedal. It's still the same regen, just in a different place.
I haven't driven a roadster, but from what I've read it doesn't take very long to get used to the regen being activated when letting off the gas, and most people end up preferring it on the gas pedal rather than the break pedal for a number of reasons.�
May 23, 2012
daniel Yep: You only step on the brake pedal when you have to slow down quicker than the maximum regen will give you, or below the creep speed. I've seen as much as 30 kW of regen, though the gauge goes to 40.�
May 23, 2012
jerry33 I hear you. What I think will happen is that you'll have to educate your foot to find the no-regen spot similar to how it's done on the Prius. Also it appears that regen is much more efficient on the Tesla. Well, we'll see.�
May 23, 2012
AndyM I have driven a Roadster, and loved it. I test drove a Leaf and missed it. I was very pleased when my Tesla salesperson told me (after driving it) that the Model S behaves like a Roadster in this way.�
May 23, 2012
BriansTesla I think the S should be able to put a lot more than 30KW regen when in a medium stop. This is very easy to program in, saves brake wear and puts the maximum into the batteries. My best consumption (about 210 kw/mi) is by coasting whenever possible, braking as little as possible and letting the regen do as much of the braking as possible. Regen is free energy and I believe the best efficiency comes when the brake pads never touch the rotors.�
May 23, 2012
dsm363 That's what I do in the Roadster. You let off of the accelerator and regen kicks in as was mentioned above. You don't recapture all the energy with regen. I think the Roadster has max efficiency going around a constant 25 mph.�
May 23, 2012
SByer Tesla made the right choice - regen on the go pedal - for a couple of reasons:
- it sure makes driving in traffic a heckuvalot better.
- you can very quickly learn the distance required for near-100% regen stops.
The Honda Fit EV (*) has a cute trick - proper regen on the go pedal only means switching from 'D' to 'B' on the 'gear' selector. Several people I did the ride along with clearly preferred 'B' once they switched, in an a-ha moment thing.
Oh, and your analog brain is far better at doing a low latency blended program than anything currently in cars like the Leaf, because you have the immediate feedback even when things like pad wear are near the limits.
(*) Yes, I will keep plugging the Fit EV. It's the best thing to come out of Honda's FCV program (because they had to develop all the EV systems anyway, since an FCV is a gimped EV), probably ever, unless they do a full-EV NSX.�
May 23, 2012
stealthnhawk the rated range is with regen accounted?�
May 23, 2012
smorgasbord Note to future Model S drivers: Driving well with heavy regen is a skill you need to practice.
It's easy to spot new Roadster drivers - they're the ones who look like they're stepping on the brakes all the time! They're not, actually, but with ICE cars we're so accustomed to letting up all the way on the gas to coast that we tend to do the same with the accelerator on Roadster. That kicks in heavy regen, which kicks on the brake lights.
If you think about it, what you really want to do is let up only to the point where the power output is near zero. This is hard to do on v1.5s that don't have the big power gauge. It's even hard on V2.x's at first. It does take some practice. As others have said, the idea is to avoid regen except when you need to actually brake. And then actually brake when you really need to stop soon. You know you're successful when after a few months your Roadster brakes squeal like stuck pigs every time you apply the brakes to stop the automatic creep. :redface:
Anyway, a few hundred miles of practice and you'll find your muscle memory able to find that near zero point on the accelerator without thinking about it. Your mileage will improve and other drivers won't think you're crazy.�
May 24, 2012
strider I just use cruise control a lot in my Roadster. As I have posted in other threads, regen on the brake pedal sucks. No one has been able to make the transition from regen to friction brakes seamless. There's always a "jump" as you pass from regen to friction. Use cruise control, learn how to hold at zero power, or flick the car into neutral if you want (Roadster will happily do this at speed). I have no interest in hypermiling - I just want to drive a fun car. I assume most Model S customers will feel the same way.�
May 24, 2012
jerry33 You really, really have to be trying to feel for it on the Prius--and even then you can't tell 95% of the time.
Unless Tesla has implemented a very different cruise control, cruise control kills range/mpg.
Agreed, that's important. Took me about two years to really learn how (~30,000 miles).
Unfortunately, illegal in many places. I don't know how they'd catch you though unless you had an accident and couldn't shift back.�
May 24, 2012
strider Why because it holds speed going up hills? I think "kill" is a very strong word. If you set the CC to 65mph and just roll you'll be fine. It's dangerous to lose too much speed climbing hills. If you want to hang out w/ the semi's be my guest. I'm not buying a sports car to go 35mph up a hill.�
May 24, 2012
Johan I drive an iMiev. It has three modes: D (medium regen), C (coast - less regen) and B (full regen i. e. all regen on letting go of the gas pedal). I drive it in B 99.9% of the time. So it seems some people are overthinking this issue...�
May 24, 2012
daniel 30 kW of regen in the Roadster is HARD braking. I don't know if the limiting factor is how fast the system can accept a charge (the HPC is I think 240 v 70 a = 16.8 kW, about half the regen charge rate) or if they just felt that more would be dangerous. I'm glad that letting up on the go pedal does not produce more.
The Model S is a heavier car, however, so the same braking feel would equate to a higher kW figure.
The rated range is at a constant 55 mph. Constant speed = no braking. Any braking will reduce range, but regen reduces range less than friction braking does. So use of regen in the city gives you better range than if you didn't have regen.�
May 24, 2012
Doug_G
Mind you, I've driven a lot of manual transmisson cars, which behave similarly, if not as strongly.�
May 24, 2012
AnOutsider I'm guessing it will be a similar situation for anyone who has driven manual and/or sports cars. In those, it does take a bit of practice learning to drive with one foot (but once you get it, it's sweeeeet)�
May 24, 2012
efusco Bear with my amateur question here...but Tesla does NOT regen with brake application, is that correct...just on release of the accelerator pedal?�
May 24, 2012
gg_got_a_tesla stealthnhawk might be referring to the EPA 5-cycle range of 265 miles; if so, I'd assume it's with the max regen possible while also being driven by someone at Tesla who knows what s/he's doing to maximize it!�
May 24, 2012
NigelM On release of accelerator.�
May 24, 2012
vfx
Only.�
May 24, 2012
daniel That is correct on the Roadster.
I'd like it to regen on the brake pedal also, the way the Prius does it, but I gather that would be a much more complex system. Toyota wanted the Prius to feel just like an automatic, so the go pedal has only a little regen, and you need to use the brake pedal to slow down more than a tiny bit. Tesla was going for the Roadster to feel like a manual sports car, where engine braking is big, although they made it even stronger.
But the PEM in the Tesla can handle much more regen than the Prius can. I've seen 30 kW and the gauge goes up to 40.
There are times when someone in front of me slows down suddenly, or a light turns red, and I need to brake harder than the regen and I have to use the brake pedal. For those times it would be nice for the brake pedal to increase the regen further. But I suppose that would have required more engineering than they wanted to mess with.
My biggest problem with the system as it is, is that it's hard to maintain a perfectly constant speed without using c/c, which in the Roadster is very awkward to engage, and doesn't work below 30 mph. Perhaps the S will have a better design for engaging and controlling the c/c. I end up just not using it.
Pretty soon you'll be able to tell us how the S feels!�
May 24, 2012
BriansTesla Programming for the brake pedal to cause regen is very basic. A $1600 motor controller we use on an electric conversion can be adjusted with a handheld tool to cause a slight regen on pedal release and brake pedal regen depending on pressure. The goal I try for is settings that produce the least consumption of energy while making it feel enough like an ICE vehicle that I can hand the key to anyone, regardless of their experience, and they can drive it easily and efficiently.
I believe it is a fact that the most efficient way from point A to point B is with the least use of brakes, the least use of regen and the most coasting possible. Of course regen is always better that the brakes sucking up energy but momentum is the number one conservation tool. That is why the ability to coast easily and often is important.
With the great efficiency of the Model S, small things such as changing the route you drive to keep from stopping at the bottom of a hill can make measurable improvements in consumption.
I would wish for a great ability to coast and enough regen on braking to allow, with careful driving, to never have the pads touch the rotors. I believe this could make a big difference in range.�
May 24, 2012
jerry33 �
May 24, 2012
daniel I agree. But the Roadster is not a car that encourages efficient driving. The Prius encourages efficient driving. The Xebra encourages careful driving. The Roadster encourages hard driving.�
May 24, 2012
dsm363 Coasting is really only good for hypermiling since when I drive my ICE, it's tough to slow myself down to the proper speed and stop without at least lightly using my breaks in city traffic. In the Roadster, it's not a problem. I just modulate my speed with the accelerator and when I'm close to needing to stop, I lift off the accelerator and let full regen kick in. It really works very well. Is it better than coasting? Maybe not but we're probably talking about small gains with coasting and the experience with regen on the accelerator is great.�
May 24, 2012
Doug_G Just to be clear, Tesla starts regen when you lift off the accelerator, and then continues to regen brake at the same level when your foot is on the brake pedal. Regen provides a substantial fraction of the braking force even under moderately strong conventional braking, which you will notice immediately if the traction control ever fires while you're braking.�
May 24, 2012
SByer I'll humbly suggest it's good to practice this situation somewhere safe by throwing the car into neutral while braking. It's instructional. Though, I'm guessing the Model S won't have the undersized vacuum assist pump issue (was that ever tweaked for later Roadsters?).
It took me less than a week in the Roadster to be able to nail a stop with nearly no brakes. I am still hunting the friction-brakeless commute (I got really, really close once - just one to many lights).
I call what I do asymmetric hyper-miling, since I never miss an opportunity to stomp the go pedal. People in econo-box genericars that shift over to an empty lane at stoplights when I'm just about there really tick me off ;-).
I think the iMev and Fit EV have the right answer - make switching into regen-on-go-pedal easy and intuitive, and let each choose their own.�
May 24, 2012
efusco Thanks, that's what I thought. so there's no advantage to turning down the regen to a lower setting, better to just adapt to the highest setting. Given the option I'd take zero regen with lifting the accelerator and max regen with increasing brake pressure...but I'm confident I'll adjust just fine.�
May 24, 2012
dsm363 I really like the regen on the accelerator and think most people will too. It takes a very short time to get used to it but once you hop back into an ICE, it's a weird feeling coasting when you let off the accelerator.�
May 24, 2012
KBF I was told at the Toronto event that the Model S in full regen mode will use the absolute max; the number seems high to me, but I believe he said the rate will be 90 kW. It's a heavy car compared to the Roadster...�
May 25, 2012
VolkerP Apparently this will not be the case in Europe because some dim-witted legislation forbids to light the brake lights on regen-only deceleration. As a consequence, Tesla will tune down regen a fair bit. But since regen power depends on speed, the threshould could be made dependent on speed instead of a fixed value.
For 1m/s� deceleration (a modest 0.1g), regen power at 65mph is 60kW versus 20kW at 22mph.
I use P = m v a with m= vehicle mass = 2000kg�
May 25, 2012
KBF Right, I should clarify: "up to 90 kW". Others can do the math to see if I'm remembering correctly.�
May 26, 2012
vfx Yes it's the max but it will not feel like the Roadster because the car weighs so much.�
May 27, 2012
efusco I wasn't sure how to interpret that relative to my Prius. Today I used my CanView and found that the 'regular' regen (foot off accelerator, no brake) varies a bit depending upon speed b/w 2kW and 5kW. Under maximal Regen braking it peaks at 25kW (likewise max 25kW output in EV mode). Just providing a frame of reference.�
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