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LTLFTcomposite
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Re: Regen and brake lights

Sat May 22, 2010 3:35 am

EVDRIVER wrote:If you need to touch the brake pads before 10 mph then you are wasting too much regen.
The regen is only braking on the front wheels. Presumably there is some logic that above a certain braking level the rear brakes must be applied too for a safe stop. The ebox or whatever didn't have to be safety tested anywhere near the way the Leaf does.
LTL
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daniel
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Re: Regen and brake lights

Sat May 22, 2010 6:25 am

EVDRIVER wrote: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.
Everything you say about efficiency applies equally if the brake pedal operates the way it does on the Prius: Brake pads are never used unless the driver calls for more braking than regen can provide (i.e. an emergency stop) or below the speed at which regen can operate.

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.

Feet off both pedals should result in coasting. Brake pedal should use only regen unless regen would not be sufficient or the vehicle speed is too slow.

This is the ASK NISSAN forum. How about Nissan telling us how the car will actually function???!!!
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garygid
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Re: Regen and brake lights

Sat May 22, 2010 7:44 am

LT...,
Yes, that would seem to be a simple, effective, even optimal implementation.

However, not all manufacturers see it that way. Thus, there remains some controversy about what "should" be done.

There are (at least) these variations:

1. Regen (perhaps even adjustable) when the foot is off both pedals. Often not zero.

2. If #1, then decreasing (or no) Regen as the "go-faster" pedal is pressed.

3. The "go-slower" pedal does not increase the Regen, but only applies mechanical brakes.

4. Some (usually small amount of) power is applied to the wheels (when stopped or at low speed), even with neither pedal pressed.

5. A "hill-holder" mode is included, to aid in getting going when stopped on hills.
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garygid
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Re: Regen and brake lights

Sat May 22, 2010 8:07 am

There are those that feel the need to mimic the "features" (and shortcommings) of the typical small or mid-size automatic transmission car.

1. The "drag" as the slowing engine tends to slow the car when the foot is taken off the "go-faster".

2. The "creep" that occurs when the (usually) slow-speed engine trys to "pull" the car when the foot is taken off the "go-slower" pedal.

3. Some form of driving with both pedals pressed, usually to help getting going in the intended direction when stopped on hills.
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2018 Tesla Model 3
2014 Tesla S, Model 3 in 2019
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garygid
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Re: Regen and brake lights

Sat May 22, 2010 8:17 am

The "pull" to mimic the typical ICE probably comes from at least these beliefs:

1. People will accept the car better if it mimics these "features"

2. People cannot, or do not want to adapt to something new.

3. If the car is "different", the user might sue, claiming that the negligent lack of a familiar feature caused an "incident".

4. If these "features" are made user-selectable (to get better performance), an un-knowing "new" user might find (or claim) the other-user's settings are too unexpexted or too unfamiliar.
See SOC/GID-Meter and CAN-Do Info
2010 Prius, now for sale
2011 LEAF, sold in 2015
2018 Tesla Model 3
2014 Tesla S, Model 3 in 2019
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EVDRIVER
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Re: Regen and brake lights

Sat May 22, 2010 12:56 pm

LTLFTcomposite wrote:
EVDRIVER wrote:If you need to touch the brake pads before 10 mph then you are wasting too much regen.
The regen is only braking on the front wheels. Presumably there is some logic that above a certain braking level the rear brakes must be applied too for a safe stop. The ebox or whatever didn't have to be safety tested anywhere near the way the Leaf does.

I was referencing the front brakes where the majority of braking occurs, of course the rears are used somewhat and it's not as though they would disconnect or modify them as they are in relation to the front stopping power regardless of the means.

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EVDRIVER
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Re: Regen and brake lights

Sat May 22, 2010 12:59 pm

garygid wrote:The "pull" to mimic the typical ICE probably comes from at least these beliefs:

1. People will accept the car better if it mimics these "features"

2. People cannot, or do not want to adapt to something new.

3. If the car is "different", the user might sue, claiming that the negligent lack of a familiar feature caused an "incident".

4. If these "features" are made user-selectable (to get better performance), an un-knowing "new" user might find (or claim) the other-user's settings are too unexpexted or too unfamiliar.

Based on that logic no one should buy and ev because they wont be filling at gas stations, they will have range anxiety, and more. So no point in changing anything. Besides as I have said at for over there years, adjustable regen can act EXACTLY like the behavior of an ICE to where no one would no the difference so why try to exclude a feature or dumb cars down. Perhaps the charge cord should look like a gas nozzle not to shock to many old people. Pardon the pun.

If I buy a motorcycle and fall over because I'm a new rider should I sue for not putting my feet down. The first time you drive a car you are educated there is a brake and clutch, should one sue for confusing them? Gary, I hope you don't have one of those electric charcoal starters, if you plug it in the first time and grab the wrong end you will burn yourself. Seriously, do you wear shirts with reflectors at night? I just put in a new light switch in my home, the box is plastic and I cut the ground wire- ooooh:) Gary, in your world nothing would change and valet attendants would need to sign waivers before accepting keys from patrons.

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EVDRIVER
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Re: Regen and brake lights

Sat May 22, 2010 1:11 pm

garygid wrote:LT...,
Yes, that would seem to be a simple, effective, even optimal implementation.

However, not all manufacturers see it that way. Thus, there remains some controversy about what "should" be done.

There are (at least) these variations:

1. Regen (perhaps even adjustable) when the foot is off both pedals. Often not zero.

2. If #1, then decreasing (or no) Regen as the "go-faster" pedal is pressed.

3. The "go-slower" pedal does not increase the Regen, but only applies mechanical brakes.

4. Some (usually small amount of) power is applied to the wheels (when stopped or at low speed), even with neither pedal pressed.

5. A "hill-holder" mode is included, to aid in getting going when stopped on hills.

There is always a modification, ask any EV MFG and they will tell you it usually takes a variable resistor. All inverters are software controlled and have variable input options for regen. A I mentioned earlier, the best design allows for strong variable regen via the accel pedal but that takes more engineering on the brake and pedal.

AndyH
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Re: Regen and brake lights

Sat May 22, 2010 1:50 pm

This is from the 1997 GM S10EV tech training manual:

If the [computer] indicates that regeneration can occur (battery state of charge, battery temperature, controller temperature, etc.), the [controller] will provide approximately 6% regeneration during a coast with the [accelerator position] sensor indicating that the accelerator pedal is not depressed. If the brake switch is closed, the [controller] will provide approximately 15% regeneration.

The US Electricar / Hughes system increases regen percentage depending on the position of the 'shift' lever. These vehicles use a standard 'auto transmission' console that includes drive and two low gears. Shifting into 2 or 1 adds more regen to simulate selecting a lower gear.

I'm expecting that the Leaf will not truly 'coast' when one releases the accelerator pedal but will use a small amount of regen. This will be too low a rate of decel to require brake lights. I expect more regen with the brake pedal, and normal pedal operated brake lights. I hope that shifting the transmission into neutral will disable regen and allow a full 'coast' mode.

Automobile function and design has evolved over the past 100 or so years and the 'proper' functions are defined by current vehicles. Maybe we'll evolve new standards as we grow more EVs, but I don't expect today's Leafs to fall far from the...ah...design tree. ;)

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Jimmydreams
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Re: Regen and brake lights

Sat May 22, 2010 1:53 pm

EVDRIVER wrote: If I buy a motorcycle and fall over because I'm a new rider should I sue for not putting my feet down. The first time you drive a car you are educated there is a brake and clutch, should one sue for confusing them? Gary, I hope you don't have one of those electric charcoal starters, if you plug it in the first time and grab the wrong end you will burn yourself. Seriously, do you wear shirts with reflectors at night? I just put in a new light switch in my home, the box is plastic and I cut the ground wire- ooooh:) Gary, in your world nothing would change and valet attendants would need to sign waivers before accepting keys from patrons.
I don't think Gary was suggesting that he believes that way, rather than that is the PERCEPTION by many about how the general public feels. And this perception is what drives GM and others into complete redesigns because of the PERCEPTION that...ohhh...let's say partial-roll down windows are unacceptable or the lack of massive cupholders will kill sales. (cough*APTERA*cough)
:|
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