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evnow
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Re: Regen and brake lights

Sat May 22, 2010 1:58 pm

EVDRIVER wrote:.. adjustable regen can act EXACTLY like the behavior of an ICE to where no one would no the difference ..
Then, I've no problems.

We shouldn't lose sight of the ultimate aim - the aim is not to have some cool tech - but it is to reduce emissions & fossil fuel use.

In my industry (IT) - this is something I keep emphasising. However cool something is from engineering perspective - it is important not to lose sight of the goal. Take the Nissan website for eg. They didn't have some basic scenarios working - but created a jazzy website ... that would get a 'F' grade from me.

It's not a cool new tech it's the most effective way to recapture as much energy to the pack under certain driving conditions and styles, the only reason I want this is it will provide significantly more energy back to the pack for me. I think this is something people don't fully understand until they own an EV for some time and monitor the regen while using such a feature. An EV, not a hybrid.
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garygid
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Re: Regen and brake lights

Sat May 22, 2010 3:11 pm

I believe the manufacturers most likely look at it one way (possible acceptance and litigation), and I look at it differently (people can adapt, adapt or die, and don't complain if you are too stupid to handle a hot cup of coffee that they ordered).

I think the brake (go-slower pedal) is where the (should be variable) Regen belongs, with none on the go-faster pedal.

The 2010 Prius will not "coast" without careful (and tedious) feathering of the go-faster pedal.

In my mind, that is a sub-optimal "human interface" design.
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Re: Regen and brake lights

Wed May 26, 2010 9:27 pm

daniel wrote:Putting all the regen on the accelerator, and allowing for hard braking when lifting your foot, opens the possibility of disastrous results if the driver accidentally lets his foot off the pedal.
I'm not too worried ... that's what Traction Control ("TC") is for; it prevents "disastrous results" during the "lift-off" condition in the same way TC is designed to control the vehicle during hard (friction brakes) braking.

I like the regen all in the "go-faster pedal", or at minimum I would like some notification during use of the brake pedal when the friction brakes are actually applied -- I'd want to minimize that!
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planet4ever
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Re: Regen and brake lights

Thu May 27, 2010 3:41 am

LEAFer wrote:
daniel wrote:Putting all the regen on the accelerator, and allowing for hard braking when lifting your foot, opens the possibility of disastrous results if the driver accidentally lets his foot off the pedal.
I'm not too worried ... that's what Traction Control ("TC") is for; it prevents "disastrous results" during the "lift-off" condition in the same way TC is designed to control the vehicle during hard (friction brakes) braking.
I don't happen to agree with daniel that foot off the accelerator should result in coasting, but I suspect the "disastrous results" he was darkly predicting might have involved another car, not your own traction control. If, that is, the brake lights don't go on until you hit the brake pedal.

I would like to have a "B" switch of some sort, which controls light vs. heavy foot-off regen. If foot-off is going to cause heavy regen then it does make sense that the brake lights should be triggered by deceleration. And perhaps it goes without saying, but tapping the brake pedal should always cause the brake lights to go on, even if there was also a deceleration switch.
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Re: Regen and brake lights

Thu May 27, 2010 6:30 am

in my Zenn before i disabled regen, it slowed down rather dramatically when i started to "coast". but i attribute that to the lightness of the vehicle. a heavier vehicle like the Leaf would not slow down nearly as much and i am not sure that brake lights would be needed.

then again, an extra bit of safety might not be a bad idea in ANY car. in any case, i would think regen in the Leaf would be similar to regen in a Prius where light brake pedal force would be regen and not friction braking anyway.

i guess we will find out soon enough
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garygid
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Re: Regen and brake lights

Thu May 27, 2010 7:05 am

Drag while and after taking the foot off the "go-faster" is a hold-over from the manual transmission technology that just couldn't do any better.

For economy, foot-off drag should not be a design goal, but a previous defect that is now unnecessary, and should be eliminated.

The amount of braking should be increased as the go-slower is pressed, with the regen, if available, being applied smoothly and gradually before the mechanical brakes are engaged.
The amount of foot-off drag could be adjustable, somewhat like cruise control, holding the amount of regen that the driver was using when the "B-mode" button was pressed.

Also, for safety, an amber (or blinking red) rear stop-warning should occur whenever the car starts to deaccelerate, even if the foot is still on the go-faster.

Rear-end collisions are very common, and an extra half-second warning to the car behind might cut that collision rate in half.
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Re: Regen and brake lights

Thu May 27, 2010 7:40 am

LEAFer wrote:I like the regen all in the "go-faster pedal", or at minimum I would like some notification during use of the brake pedal when the friction brakes are actually applied -- I'd want to minimize that!
Note that the Prius minimizes use of friction (brake pad) braking even though MOST of the regen is on the brake pedal. I like completely separate pedal functions: Accelerator for accelerating, brake for braking; AND minimize use of friction braking by having the brake pedal use ONLY regen braking unless regen would not be adequate, and then and only then use the brake pads.

This simply makes sense. The only thing the Prius does wrong is putting a small amount of regen on the accelerator pedal to mimick an automatic. This results in making it very difficult to coast when you want to, since you have to find exactly the right pedal position. Separating the functions means you can go faster when you want to, go slower when you want to, and coast when you want to. With hard braking (regen) on the accelerator pedal, coasting is very difficult.
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Re: Regen and brake lights

Thu May 27, 2010 11:00 am

planet4ever wrote:
LEAFer wrote:
daniel wrote:Putting all the regen on the accelerator, and allowing for hard braking when lifting your foot, opens the possibility of disastrous results if the driver accidentally lets his foot off the pedal.
I'm not too worried ... that's what Traction Control ("TC") is for; it prevents "disastrous results" during the "lift-off" condition in the same way TC is designed to control the vehicle during hard (friction brakes) braking.
I don't happen to agree with daniel that foot off the accelerator should result in coasting, but I suspect the "disastrous results" he was darkly predicting might have involved another car, not your own traction control. If, that is, the brake lights don't go on until you hit the brake pedal.

I would like to have a "B" switch of some sort, which controls light vs. heavy foot-off regen. If foot-off is going to cause heavy regen then it does make sense that the brake lights should be triggered by deceleration. And perhaps it goes without saying, but tapping the brake pedal should always cause the brake lights to go on, even if there was also a deceleration switch.
I had assumed that strong regen (no matter by what pedal) turns on the brake lights. That's how Tesla/ACP systems work. And the "disastrous results" would then be more likely the "slippery" kind, i.e. losing traction due to wet (or other slip) conditions. The TC would limit the deceleration (regen) in that case.
But everything in your last paragraph makes sense, too. Adjustable regen ! 8-)
daniel wrote:
LEAFer wrote:I like the regen all in the "go-faster pedal", or at minimum I would like some notification during use of the brake pedal when the friction brakes are actually applied -- I'd want to minimize that!
Note that the Prius minimizes use of friction (brake pad) braking even though MOST of the regen is on the brake pedal. I like completely separate pedal functions: Accelerator for accelerating, brake for braking; AND minimize use of friction braking by having the brake pedal use ONLY regen braking unless regen would not be adequate, and then and only then use the brake pads.
Minimizing use of friction brakes is (IMHO) an important goal. Although we disagree on the regen-via-go-faster pedal, there is one down side to my preference I must admit: When the traction battery is "full" the energy from regen has nowhere to go (see discussion in another thread). And that causes an inconsistency, because the "go-faster" pedal behaves differently depending on current State-of-Charge :|
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johnr
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Re: Regen and brake lights

Thu May 27, 2010 3:18 pm

LEAFer wrote:When the traction battery is "full" the energy from regen has nowhere to go (see discussion in another thread). And that causes an inconsistency, because the "go-faster" pedal behaves differently depending on current State-of-Charge :|
In the event the battery is full, the regen energy could be diverted to a resistive load. I have no idea if they will do that or not, though. And I really hope the go-slower pedal will feature variable regen, reserving the brakes to be applied *only* when it's impossible to stop fast enough with the regen alone.
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planet4ever
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Re: Regen and brake lights

Thu May 27, 2010 3:20 pm

LEAFer wrote:When the traction battery is "full" the energy from regen has nowhere to go (see discussion in another thread). And that causes an inconsistency, because the "go-faster" pedal behaves differently depending on current State-of-Charge :|
Well, the discussion I recall (don't remember which thread) concluded there were several places the energy could go, including having the regen work as usual but feed the current back to the engine's generator, which (acting as a motor) would spin the engine, just like in the bad old days. Naturally no fuel and no spark, but lots of compression and lots of heat for the radiator to dissipate.
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