Yanquetino
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Regen and brake lights

Fri May 21, 2010 7:06 pm

As some of you already know, AC Propulsion uses a clever bit of programming in their eBox and "trial" Mini Es to sense when the vehicles' regen merits illuminating the brake lights. This is how Stefano Paris describes it in his "eBox First Peek":
In case you are wondering about aggressive regen and notifying drivers behind you of your deceleration via brake lights, don't worry because AC Propulsion has already figured this out. Their motor control samples motor speed at something like 10Hz, and since the motor drives through a fixed ratio, motor speed is an unambiguous indicator of vehicle speed. So, by continually sampling speed one knows when the car is slowing down, and the brake lights are turned on automatically if the deceleration exceeds a low threshold. It works in reverse too. The brake lights also come on with actuation of the brake pedal as in a normal car. Interestingly, you can be using quite strong regen holding speed steady on a downhill and the brake light will not come on.

My question: will the Nissan Leaf boast a similar feature?

darelldd
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Re: Regen and brake lights

Fri May 21, 2010 7:23 pm

Yanquetino wrote:My question: will the Nissan Leaf boast a similar feature?

I'm not sure it is (as) relevant since the LEAF doesn't have the same sort of "pedal lift" regen of the ACP cars. To slow the car with any authority, I understand that the brakes pedal must be used (blending regen and brakes) and therefor making the brake light situation somewhat simple.
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LTLFTcomposite
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Re: Regen and brake lights

Fri May 21, 2010 7:25 pm

I never knew this was a problem. How is that better than just having a switch activated by the brake pedal?
LTL
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evnow
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Re: Regen and brake lights

Fri May 21, 2010 7:25 pm

Personally I don't like the idea of regen & slowing when I'm off the "gas" pedal.It is a perfect way to coast.
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LTLFTcomposite
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Re: Regen and brake lights

Fri May 21, 2010 7:32 pm

evnow wrote:Personally I don't like the idea of regen & slowing when I'm off the "gas" pedal.It is a perfect way to coast.


Yeah I saw that debate earlier but didn't weigh in. No gas or brake should be coast, not "brake a little".
LTL
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EVDRIVER
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Re: Regen and brake lights

Fri May 21, 2010 9:53 pm

If you need to touch the brake pads before 10 mph then you are wasting too much regen. I have driven Tom Gage's Ebox and the regen is variable on the accel pedal from 0-100% with a dash mounted slider, the brakes still have regen. This is a brilliant system and for those that truly understand the benefits and to use it can reap serious efficiency rewards over systems with most of the regen on brakes alone. On full regen you can stop the car with four passengers going downhill at a good clip and not touch the brakes until about 3 mph or so. If you live in a hilly area this type of system will greatly increase your range and it is FULLY adjustable for those that complain about coasting. There is no way to describe 300 plus amps of full regen and how powerful it is in stopping a car. Car makers need to devise a better regen system with a reverse HEPI (or eq) system that varies regen greatly for braking or offers adjustable regen like the ACP system. Their entire system is amazing in it's design and performance and the reason Tesla uses it. For the driving enthusiast full regen off pedal is really fun once you get used to it. I have owned many EVs and driven almost every OEM EV built and there is nothing that compares, the beauty is the driver can set the level desired. Please don't mention the MINI EV because BMW botched that one. I hope Nissan has a way to adjust this or I'm going to have to hack the inverter to find a way to make it so. If you live in the flats and drive like an old fart you wont care or miss it. No comments please Gary- I know you want to coast.

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planet4ever
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Re: Regen and brake lights

Fri May 21, 2010 11:43 pm

I'm just an old fogey, not a driving enthusiast, but I definitely want to be able to hold my speed down while going downhill without having to use the brake pedal. I grew up using second gear for that, and I love the fact that our Prius does it in B mode.

You won't see any brake lights if the car ahead of you is using second gear, so why should you see them with regen? Though I admit that using deceleration to trigger the lights sounds brilliant.
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EVDRIVER
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Re: Regen and brake lights

Sat May 22, 2010 12:22 am

planet4ever wrote:I'm just an old fogey, not a driving enthusiast, but I definitely want to be able to hold my speed down while going downhill without having to use the brake pedal. I grew up using second gear for that, and I love the fact that our Prius does it in B mode.

You won't see any brake lights if the car ahead of you is using second gear, so why should you see them with regen? Though I admit that using deceleration to trigger the lights sounds brilliant.



True and that's different than hard stopping. With full non-braking regen on the ebox one is plastered in the seat belt, the stopping power is amazing. In fact you could drive all over without using the brakes until the regen breaks at below a few MPH. Fun to experiment with while driving.

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garygid
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Re: Regen and brake lights

Sat May 22, 2010 12:51 am

Here, it would be better to have amber (yellow, or green-plus-red LEDs) on the upper, center brake light whenever ANY deacceleration is begun, even just reducing pressure on the "go-faster" pedal.

That earlier-warning amber light (before the foot presses the "go-slower" pedal enough to change the light to the standard "red") would typically give following drivers almost an extra half-second warning of a quick stop in progress ahead (the most common accident situation here).

I believe that this "early-warning" light would be easy and inexpensive to implement, and significantly cut down on rear-end crashes.
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LTLFTcomposite
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Re: Regen and brake lights

Sat May 22, 2010 3:29 am

I guess I just don't understand this conversation. I thought the way it worked is the brake pedal called for increasing levels of regen braking up to a point, beyond which the friction brakes are applied. The brake lights come on whenever the brake pedal is applied, as the implication is that the driver is slowing or stopping. B mode applies regen braking to control vehicle speed on a long downgrade, and is not intended for slowing the vehicle in normal circumstances. The implication of B mode isn't that the vehicle is slowing, just controlling its speed, so brake lights should not come on. And when you don't have your foot on either pedal, power is neither applied nor drawn from the motor/generator, so the car just gradually slows from internal friction, rolling resistance, and wind resistance.

Other than making B mode variable, which would be nice but a rarely used feature for most, I don't see how that could be improved.
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