AndyH
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Re: Regen and brake lights

Tue Jun 01, 2010 11:36 pm

garygid wrote:At high speed, one suddenly takes one's foot OFF the "go-faster", and ... what? ... sudden maximum regen-braking until zero mph is reached?

No, I do not think that strong, abrupt braking action would be acceptable!


Which is why they're not going to do that! Give them a break - they're engineers, yes, but there are technicians there to keep them straight! :lol:

Other commercial EVs that add regen when the operator removes their foot from the accelerator pedal use about 6%. It's very small and designed to mimic engine braking when in a high gear.

I'm one of the sickos that prefers a manual transmission (sorry to let you down, evnow!) and I really like the accel and decel control one has with a stick. But none are likely to enjoy the abrupt nature of pulsing the accelerator pedal in second gear. :D

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Re: Regen and brake lights

Wed Jun 02, 2010 12:12 am

This sicko has never owned a vehicle with an automatic transmission as a matter of policy. I'm trying to skip straight from a stick shift to no shift. :D
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LTLFTcomposite
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Re: Regen and brake lights

Wed Jun 02, 2010 5:44 am

AndyH wrote:...I really like the accel and decel control one has with a stick...


When you use the transmission and engine to slow a car, aren't you just transferring wear and tear from cheap parts (brake pads) to expensive parts (gears, clutches, CV's etc)? Except for long downgrades I've never understood the benefit of downshifting.
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garygid
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Re: Regen and brake lights

Wed Jun 02, 2010 8:12 am

LTFT...
You are correct.

Previously:
I was not suggesting that Nissan would do such an implementation, but rather trying to illustrate why "kballs" suggestion would not work well.

Braking tends to "throw" the driver forward, increasing pressure on the pedal being used. So, using the go-faster for braking is not really a great idea.
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garygid
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Re: Regen and brake lights

Wed Jun 02, 2010 8:35 am

The 2010 Prius assumes that, with your foot (almost) OFF the go-faster pedal, that you want to be slowing down. So, it invokes some regen, zero with the foot slightly on the pedal, and gradually increasing to a larger amount (which depends upon vehicle speed) as the foot is gradually removed from the pedal. Nothing "abrupt", a very smooth emulation of typical automatic transmission "drag". Likewise, there is a further, smooth increase in the regen-braking as one applies pressure to the go-slower. Integration with the gradual application of mechanical brakes is also smooth and seamless. It does not give any clear indication (as far as I know) as to when the disc brakes are being used.

However, when driving for economy, that is a poor assumption, and drag-free, zero-power "coasting" is what one really needs.

I suspect the "coasting" will eventually appear, first as a user-controlled setting, as EVs evolve and people become more experienced e-drivers.

If the LEAF has "coasting", I will be surprised, but that would be a "plus" in my decision to actually buy one.
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MikeBoxwell
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Re: Regen and brake lights

Wed Jun 02, 2010 9:52 am

Every electric car I've ever driven handles regenerative braking in a different way. Some of them are good, some of them are very good, and some haven't quite worked it out just yet.

When I drove the Nissan LEAF mule last month, there was minimal regenerative braking from taking your foot off the accelerator, and the brake pedal activated the mechanical brakes. I'm told that the production LEAF will incorporate more regenerative braking, although nobody could tell me how that would be activated.

The G-Wiz activates regenerative braking through the brake pedal: the harder you press the brake pedal, the more regenerative braking you get. If you need lots of braking because you're stopping in a hurry, then the mechanical brakes get activated. Thanks to some really clever software on the later cars, most people won't feel the difference between regenerative braking and mechanical braking. When you are just driving along and take your foot of the pedal, there is a tiny amount of regenerative braking going on, but not a lot - the car happily coasts along quite nicely. The new REVA NXR is even better with regards to regenerative braking. Quite frankly, in this regard, REVA are the very best in the industry when it comes to incorporating regenerative braking. It really is very impressive indeed.

The Tesla Roadster handles regenerative braking in a very different way. You take your foot off the accelerator and the regenerative braking kicks in straight away. Leave your foot off the accelerator and the car will just come to a halt. If you use the brake pedal, that just activates the mechanical brakes. Basically, you don't need to use the brake pedal at all in most driving - just the accelerator. However, there is a fair amount of 'grab' in the regenerative braking system and it is up to the driver to feather the throttle to give a smooth drive. But then, you don't drive a Tesla for its smooth drive, right?

The Modec electric van incorporates regenerative braking when you take your foot of the accelerator, but its relatively minimal. There is no way to increase the regenerative braking and when you put your foot on the brake pedal, you're activating the mechanical brakes. The Aixam Mega City is similar.

The Mitsubishi i-MiEV has two modes for regenerative braking: relatively modest when you're in DRIVE or ECO mode, but significantly more in BOOST mode. I tend to drive the car in ECO mode for most of the time, shifting to BOOST when I want to slow down. The regenerative braking effect reduces as the speed reduces and shuts down at around 8mph and the car then just creeps forwards, which gives the car a similar feel to a gasoline automatic car. As soon as you press the brake pedal, the mechanical brakes kick in.

I had the chance to try the Mitsubishi i-MiEV with zero regenerative braking recently and I was impressed with how far the car would just roll. I personally think Mitsubishi should change the way regen works on their car to remove regen braking completely in ECO mode and max it out under BOOST so that it can completely stop the car.

With my G-Wiz, I hardly ever activate the mechanical brakes. In fact, I think I've probably only ever activated the mechanical brakes a dozen times in the past four years. With the i-MiEV, unless I have to come to a complete stop I rarely use the brakes. I drove about five miles this morning on a mixture of busy freeway, fast trunk road, and urban driving. Until I stopped outside my house I didn't use the brake pedal once.

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EVDRIVER
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Re: Regen and brake lights

Wed Jun 02, 2010 5:39 pm

MikeBoxwell wrote:Every electric car I've ever driven handles regenerative braking in a different way. Some of them are good, some of them are very good, and some haven't quite worked it out just yet.

When I drove the Nissan LEAF mule last month, there was minimal regenerative braking from taking your foot off the accelerator, and the brake pedal activated the mechanical brakes. I'm told that the production LEAF will incorporate more regenerative braking, although nobody could tell me how that would be activated.

The G-Wiz activates regenerative braking through the brake pedal: the harder you press the brake pedal, the more regenerative braking you get. If you need lots of braking because you're stopping in a hurry, then the mechanical brakes get activated. Thanks to some really clever software on the later cars, most people won't feel the difference between regenerative braking and mechanical braking. When you are just driving along and take your foot of the pedal, there is a tiny amount of regenerative braking going on, but not a lot - the car happily coasts along quite nicely. The new REVA NXR is even better with regards to regenerative braking. Quite frankly, in this regard, REVA are the very best in the industry when it comes to incorporating regenerative braking. It really is very impressive indeed.

The Tesla Roadster handles regenerative braking in a very different way. You take your foot off the accelerator and the regenerative braking kicks in straight away. Leave your foot off the accelerator and the car will just come to a halt. If you use the brake pedal, that just activates the mechanical brakes. Basically, you don't need to use the brake pedal at all in most driving - just the accelerator. However, there is a fair amount of 'grab' in the regenerative braking system and it is up to the driver to feather the throttle to give a smooth drive. But then, you don't drive a Tesla for its smooth drive, right?

The Modec electric van incorporates regenerative braking when you take your foot of the accelerator, but its relatively minimal. There is no way to increase the regenerative braking and when you put your foot on the brake pedal, you're activating the mechanical brakes. The Aixam Mega City is similar.

The Mitsubishi i-MiEV has two modes for regenerative braking: relatively modest when you're in DRIVE or ECO mode, but significantly more in BOOST mode. I tend to drive the car in ECO mode for most of the time, shifting to BOOST when I want to slow down. The regenerative braking effect reduces as the speed reduces and shuts down at around 8mph and the car then just creeps forwards, which gives the car a similar feel to a gasoline automatic car. As soon as you press the brake pedal, the mechanical brakes kick in.

I had the chance to try the Mitsubishi i-MiEV with zero regenerative braking recently and I was impressed with how far the car would just roll. I personally think Mitsubishi should change the way regen works on their car to remove regen braking completely in ECO mode and max it out under BOOST so that it can completely stop the car.

With my G-Wiz, I hardly ever activate the mechanical brakes. In fact, I think I've probably only ever activated the mechanical brakes a dozen times in the past four years. With the i-MiEV, unless I have to come to a complete stop I rarely use the brakes. I drove about five miles this morning on a mixture of busy freeway, fast trunk road, and urban driving. Until I stopped outside my house I didn't use the brake pedal once.



There are ways to adjust the Tesla regen from 0-to full. This is such a silly debate because having it adjustable gives everyone the regen they prefer on pedal.

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Re: Regen and brake lights

Wed Jun 02, 2010 5:53 pm

MikeBoxwell wrote:The Tesla Roadster handles regenerative braking in a very different way. You take your foot off the accelerator and the regenerative braking kicks in straight away. Leave your foot off the accelerator and the car will just come to a halt. If you use the brake pedal, that just activates the mechanical brakes. Basically, you don't need to use the brake pedal at all in most driving - just the accelerator.

I like the Tesla principal -- I would not complain if that's how the LEAF ended up doing it. I have driven the Roadster. For anyone who hasn't ... look for a Tesla Store near you; they're pretty generous about test drives. And just so that the "... will just come to a halt." does not create false impressions ... as mentioned elsewhere, your right foot has full control of the deceleration (=regen=charging the battery), but even in the case of accidental (?unintended?) complete pedal-lift, the Roadster goes from 60-15 (mph) in about 700feet (without brake lining wear :) and just in time for you to take that turn you were planning ...). So, yes, it's strong, but not an emergency braking kind of maneuver. This also means (in reply to a comment somewhere) that the regen braking is not strong enough to propel your body forward and/or cause you to push back on the accelerator pedal. You definitely feel it, though. (The "Tesla regen-principal" might come in handy in an emergency ;) think medical emergency ... :cry: )

Another interesting result of the "Tesla way of doing it" (Mini-E does it that way too :P ): When on cruise control down a long hill .... the regen is strong enough that the car won't accelerate, yet you're getting the benefit of some very massive battery charging :D
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Re: Regen and brake lights

Wed Jun 02, 2010 6:09 pm

Personally, I'd like zero pressure on gas pedal = 100% coast (no regen)
Pressure on brake pedal = regen (more pressure, more regen)

I live in some hilly terrain....I'd like to be able to completely coast down the hills at speed using virtually zero power. If there was regen involved, I'd constantly be switching back and forth.
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garygid
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Re: Regen and brake lights

Wed Jun 02, 2010 7:43 pm

Me too, Jimmy.

Between no-coasting and noise-making ... it starts to get "uglified".
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