Model S regen

[JRP3]

Around here school buses have strobe lights and the little stop sign that pops out every time they stop. Thinking more about this topic as I drove home this evening I'm more in favor of just leaving things as they are. I don't think I want any driver having a signal that means "I'm only slowing down" or some such thing. Someone could see that signal and think "well it's only slowing down", then get distracted, and I suddenly have to slam on the brakes harder while he's not paying attention. When I see brake lights it really just means pay extra attention and be ready to stop if necessary, and then I make the judgement call by watching how fast the vehicle is actually slowing down. I'm afraid anything else will just confuse the issue. What happens when going uphill? You can stop quickly with little brake or regen, which might only signal the "mild slowdown" signal.

 

[strider]

It wasn't a school bus - it was one of these: T2140 USA

Most likely a commuter bus run by one of the local companies to ferry employees to work.

Can't find any good pics of the rear or discussion on how the lights work.

 

[TEG]

Like this? :

I see a lot of those European buses on 101 lately for use as corporate shuttles (Google, Yahoo, etc...)
Some of the larger valley employers offer wifi & rides to their employees that live up in S.F.

 

[SByer]

Some of the larger valley employers offer wifi & rides to their employees that live up in S.F.

Or even just along routes in the south bay. There are some double-decker ones, too. And unlike the VTA busses, there's plenty of space for bikes. And the seats are comfy.

 

[rabar10]

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[Doug_G]

View attachment 3229
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I think someone is trying to suggest that this thread is off on a, uh, tangent.

 

[m.rudolf]

Just to better understand Tesla's regenerative breaking: I am used to Toyota's HSD system that uses a very mild form of regenerative breaking when you lift the accelerator and employs progressively more regen when pressing the brake pedal up to a point when it engages the hydraulic brakes. I initially thought Tesla's system would be similar, reducing the impact of vehicle weight on range.

From this forum I gather Tesla's system works differently: regenerative braking is only used when lifting the accelerator and as soon as you start pressing the brake pedal the hydraulic brakes are put to work. Is this correct?

 

[Doug_G]

Just to better understand Tesla's regenerative breaking: I am used to Toyota's HSD system that uses a very mild form of regenerative breaking when you lift the accelerator and employs progressively more regen when pressing the brake pedal up to a point when it engages the hydraulic brakes. I initially thought Tesla's system would be similar, reducing the impact of vehicle weight on range.

From this forum I gather Tesla's system works differently: regenerative braking is only used when lifting the accelerator and as soon as you start pressing the brake pedal the hydraulic brakes are put to work. Is this correct?

That is correct. It also ignores the fact that you can easily and instantly adjust the amount of regen by simply lifting or lowering your foot.

 

[strider]

Just to better understand Tesla's regenerative breaking: I am used to Toyota's HSD system that uses a very mild form of regenerative breaking when you lift the accelerator and employs progressively more regen when pressing the brake pedal up to a point when it engages the hydraulic brakes. I initially thought Tesla's system would be similar, reducing the impact of vehicle weight on range.

From this forum I gather Tesla's system works differently: regenerative braking is only used when lifting the accelerator and as soon as you start pressing the brake pedal the hydraulic brakes are put to work. Is this correct?

Correct. In my experience, no manufacturer with the "regen on brake pedal" system has been able to engineer a smooth transition from regen to mechanical brakes. I have driven every generation of Prius and the transition from regen to mechanical brakes gives me whiplash (it has gotten better over the years but it's still a jolt). With the Tesla (doesn't the Leaf work the same way so maybe this will be an EV vs hybrid thing?) I have complete control over regen with the accelerator and I also know that the mechanical brakes will work the same every time no matter what. This is a MUCH better system. I have let a number of people drive my Roadster and after 5 minutes they have it down and rave about it. Not sure where you're based but if you're in the Bay Area you're welcome to drive my Roadster to get a feel for it.

The one negative thing about the Roadster is that if you're using the Cruise Control and you cancel the current setting the car will go into full regen (because you're not pressing on the accelerator) which can be startling. I drive with CC a lot so it took me a little while to remember to put my foot on the accelerator to ease the transition. But this is something Tesla could fix with software. Although having said that, I'm not sure what the logic would look like... If you cancel CC then use light regen but if you touch the brakes then go to full regen? Could end up w/ the same problem as the Prius system. Hmm... have to think about what would be optimal here.

 

[Doug_G]

Correct. In my experience, no manufacturer with the "regen on brake pedal" system has been able to engineer a smooth transition from regen to mechanical brakes.

I've driven a Leaf, and it seems to be a bit better implemented. It gives you about 30% regen when you lift off, and then increases to 100% as you press the brake pedal. Now I only drove it briefly, but I didn't notice anything jarring about the transition. My suspicion is they're slightly engaging the friction brakes from the get-go, so there's a bit of loss of energy there.

 

[TEG]

That is correct. It also ignores the fact that you can easily and instantly adjust the amount of regen by simply lifting or lowering your foot.

And you hear of Roadster drivers doing some "one pedal driving" using the heavy regen instead of the brake pedal.
But with cars like the LEAF and Prius there isn't enough "off pedal" regen to really do that. So you are at least using the brake pedal regularly to turn up the regen.

 

[vfx]

....
The one negative thing about the Roadster is that if you're using the Cruise Control and you cancel the current setting the car will go into full regen ....

In the "CC off" situation (which is jarring) maybe the regen comes on slowly. Say 6 seconds.

 

[m.rudolf]

... so maybe this will be an EV vs hybrid thing?)...

I certainly don't want to turn this into an EV vs. hybrid or Tesla vs. Nissan thread. But interestingly Nissan's Leaf seems to regeneratively brake when using the brake pedal (up to a point) as does the Volt. I think Tesla's decision to only use mild regen as a replacement for "motor-braking" isn't due to limited charging capabilities of their massive batteries, limitations of the high-voltage-circuitry or their inability to make a smooth transition from regen to hydraulic braking (ever driven a brake-by-wire Mercedes?). My guess is that this decision is mainly based on the limitations of braking with the rear wheels so I hope to see more regeneration in the Model X (which will certainly need it to keep it's range up).

On the point of canceling the cruise control: that was one of my main concerns. I tend to heavily use cc as well and having the car start to decelerate quickly when canceling the cc would really disturb me. That may be one reason for the Model S as a luxury sedan to have less/smoother regen than the sporty Roadster.

 

[Robert.Boston]

From a purely driver-oriented view, I applaud Tesla's decision to make the brake pedal exclusively linked to the mechanical brake. That puppy needs to work consistently and reliably for my safety. The more bells-and-whistles you add into its operation, the less comfortable I feel with its reliability.

 

[gg_got_a_tesla]

From a purely driver-oriented view, I applaud Tesla's decision to make the brake pedal exclusively linked to the mechanical brake. That puppy needs to work consistently and reliably for my safety. The more bells-and-whistles you add into its operation, the less comfortable I feel with its reliability.

Amen! No software -which I inherently don't trust, as a s/w engr myself - in play when hitting the brake pedal, please!

 

[NigelM]

I see a difference between a high performance Tesla and a more sedate Leaf. The faster I drive the more I want brakes that will do exactly as my foot tells them.

 

[DrComputer]

After driving a Lexus LS600hL for four years now I have come to like brake-by-wire. Yes, it does feel a bit different than traditional hydraulic brakes but it does offer many more features. In the Lexus is allows the car's advanced pre-collision system to stop the car in an emergency. It also has a nice brake-hold feature that allows the car to hold the brakes automatically without the driver having to press the pedal (handy on a hill or when stopped at a really long light). So, I'm kind of disappointed that Tesla chose the less sophisticated hydraulic system in such an advanced car. There has also not been any mention of other advanced systems like pre-collision, lane assist, blind spot monitoring, heated and cooled seats.

 

[gg_got_a_tesla]

There has also not been any mention of other advanced systems like pre-collision, lane assist, blind spot monitoring, heated and cooled seats.

From what's known thus far,

pre-collision - don't know
lane assist - don't know
blind spot monitoring - yes
heated seats - yes
cooled seats - no

 

[DrComputer]

From what's known thus far,

pre-collision - don't know
lane assist - don't know
blind spot monitoring - yes
heated seats - yes
cooled seats - no

This is what is holding me back from placing a reservation for this car now. I'd love to go all electric and replace the Lexus with the Model S. But so far it looks like a significant step down in terms of features and luxury from my 4 year old car. Granted, the LS600hL did cost a bit more than the Model S, but I feel if Tesla wants to make a "luxury" car they at least have to be on-par with what is already on the market... if not ever better. It was ok with the Roadster to "give up" many expected luxuries for the price because it was new and groundbreaking... but I don't think I will be as forgiving with the Model S.

 

[WhiteKnight]

Granted, the LS600hL did cost a bit more than the Model S

Yeah the original sticker is $106,035. A used LS600hL today costs about as much as a brand new 160 mile Model S after rebate.