How does Eco mode really work?

[Don]

I'm gonna let the horse die too - Some people will never be convinced of the obvious

If you got as much regen in D as in any other mode, they certainly wouldn't have gone to the trouble to give you the other modes - Just drive in D and use the brake pedal, since you claim you get just as much regen doing it that way as any other

Here's an explanation by Mitsu posted to a forum as to why it's not possible to activate the brake lights when you're in the regen only modes - It's against the law in some places. This post also tells us how the ordinary brakes and regen are linked

Howard,

We agree that the regenerative braking system on the i-MiEV produces a significant speed reduction to the vehicle when you take your foot off the accelerator (much like using the gears in a manual vehicle).

Under Australian Design Rule 31/02 "Brake Systems for Passenger Cars", we are specifically precluded from generating a signal to illuminate the brake lights when the brake pedal is not being pushed. One beneficial result of this is an increased service life for the brake pads, discs, shoes and drums!

In the 12MY version of i-MiEV, Mitsubishi Motors has linked the use of the ordinary service brakes with additional regenerative braking function and under these circumstances the activation of the service brakes is specifically required to generate a signal to illuminate the stop lamps.

Regards,

Mitsubishi Motors

I didn't get great grades in English comprehension, but he sure seems to be saying that the service (hydraulic) brakes must be activated to enable the automatic regen which was added to the newest version of the car - They linked the use of ordinary brakes with additional regen . . . .


Don

 

[PV1]

Each drive mode gives you a set level of regen (braking force in kW), D is low, ECO is medium, and B is high. Lightly pressing the brake pedal takes all three modes to a higher range of regen, still maintaining three distinct levels for the drive modes. Overall, the same amount of regeneration (kWh, energy sent back to the battery) is available, no matter what drive mode. The only difference is how quickly you decelerate.

The first little bit of pedal travel has no friction braking force. Once the regenerative brakes max out (for the respective drive mode), the friction brakes seamlessly engage, the same as an ICE without regenerative brakes. There is no set on/off, everything is gradual.

You can get a feel of the friction brakes and where they engage by slowing pushing the brake pedal in neutral, road conditions permitting at your own risk. Neutral will completely disable regen.

 

[fjpod]

I'm gonna let the horse die too - Some people will never be convinced of the obvious

If you got as much regen in D as in any other mode, they certainly wouldn't have gone to the trouble to give you the other modes - Just drive in D and use the brake pedal, since you claim you get just as much regen doing it that way as any other

Here's an explanation by Mitsu posted to a forum as to why it's not possible to activate the brake lights when you're in the regen only modes - It's against the law in some places. This post also tells us how the ordinary brakes and regen are linked

Howard,

We agree that the regenerative braking system on the i-MiEV produces a significant speed reduction to the vehicle when you take your foot off the accelerator (much like using the gears in a manual vehicle).

Under Australian Design Rule 31/02 "Brake Systems for Passenger Cars", we are specifically precluded from generating a signal to illuminate the brake lights when the brake pedal is not being pushed. One beneficial result of this is an increased service life for the brake pads, discs, shoes and drums!

In the 12MY version of i-MiEV, Mitsubishi Motors has linked the use of the ordinary service brakes with additional regenerative braking function and under these circumstances the activation of the service brakes is specifically required to generate a signal to illuminate the stop lamps.

Regards,

Mitsubishi Motors

I didn't get great grades in English comprehension, but he sure seems to be saying that the service (hydraulic) brakes must be activated to enable the automatic regen which was added to the newest version of the car - They linked the use of ordinary brakes with additional regen . . . .


Don

No, I think what he was trying tosay is that you have to put your foot on a brake pedal for brake lights to activate. He said it inaccurately.

 

[Don]

Each drive mode gives you a set level of regen (braking force in kW), D is low, ECO is medium, and B is high. Lightly pressing the brake pedal takes all three modes to a higher range of regen, still maintaining three distinct levels for the drive modes. Overall, the same amount of regeneration (kWh, energy sent back to the battery) is available, no matter what drive mode. The only difference is how quickly you decelerate.

At last! Now we're getting somewhere! Some cold, hard, facts as opposed to all the opinions expressed in this thread

What level of regen do you get when braking in Neutral, which has none? Same as D? 0r Eco? Or B? Or something completely different?

Please post where you obtained this information, because search as I might, I couldn't find anything which would even give me a clue that this is actually how it works

Don

 

[PV1]

The bottom of my post. Neutral has no regen at all. Any braking is totally friction. D with no pedals has some regen, although not enough to do any significant deceleration. D with some brake pedal is enough to slow you down on a downgrade.

My source is my car. This is exactly how it functions while driving. I can upload a video if you like, although I'm sure you can easily replicate anything I've found out. Come up to a red light in D, put a little pressure on the brake pedal, and shift down through ECO and B, and you'll feel the car increase regen with each step. You'll want to do this with your speed in the 20-40 mph range. The meter can be pegged in ECO, but B will still give you a little bit more.

 

[JoeS]

1. [Eco Mode] Activates an electro-mechanical constraint on the accelerator, making it physically harder to depress the pedal. This is simply a tactile feedback device meant to counteract a driver's tendency to leadfoot....

I don't agree with item 1. The pedal has the same resistance in all modes. ECO seems to have more resistance because you're pushing much further down on the pedal compared to D or B, but it doesn't actually change (does the pedal push up or drop down when switching between D and ECO?)...

PV1, you are right and I am wrong! Even though I could have sworn what I wrote was the case and based on something I had read (can't find it), I experimented quite a bit on a longer drive last night I realize that it is simply the gain change that is giving me the perception increased resistance. Neat trick, I must say. I've gone back and added my retraction to that original post of mine, and thank you for correcting me.

 

[HParkEV]

I don't think anyone is disputing the fact that B gives you more regen than Eco and Eco more than D at any particular position of the brake pedal. However there seems to be a disagreement still between Don and myself, as to the variability of regen. I still believe that regen is variable depending on how 'deep' you press the brake pedal, which is most easily observed in D mode going down hill. Slight brake application will give you less regen than more firm brake application at the same speed. There must be a position sensor on the brake, not just a switch, that the computer can use in order to determine the amount of regen that is appropriate for a given drive mode and brake pedal position. Or perhaps it uses a pressure sensor in the hydraulic system, not just an on-off type of sensor, but one that has variable output that tells the computer how firmly the pedal is pressed. I think we have already concluded that such a pressure sensor in the brake system must exist anyway for the 'creep' function to work the way it does (creep being shut off at a certain brake pressure threshold). I will speculate that the same sensor may be used to vary the amount of regeneration while braking depending on the output of this sensor, regardless of what the friction system may be doing at the same time.

 

[Don]

I don't think anyone is disputing the fact that B gives you more regen than Eco and Eco more than D at any particular position of the brake pedal.

The 'dispute' seems to be that no matter what mode you use or how you drive, you get the same amount of regen in the end - Driving in D mode and using the brake pedal gives you the same amount of regen in a stop as does driving in B mode and not touching the brake pedal at all . . . . or so they say

However there seems to be a disagreement still between Don and myself, as to the variability of regen. I still believe that regen is variable depending on how 'deep' you press the brake pedal, which is most easily observed in D mode going down hill. Slight brake application will give you less regen than more firm brake application at the same speed.

You may be 100% correct, but I still believe that doing this is blending friction braking with regenerative braking. You press the pedal harder and you not only get more regen, you get more friction braking as well

There must be a position sensor on the brake, not just a switch, that the computer can use in order to determine the amount of regen that is appropriate for a given drive mode and brake pedal position. Or perhaps it uses a pressure sensor in the hydraulic system, not just an on-off type of sensor, but one that has variable output that tells the computer how firmly the pedal is pressed.

I think you may be correct here too - I just wish we had some printed info from Mitsu telling us this is how it works, as opposed to what we think is happening based on seat of the pants feel and what the charge indicator is doing

In the next couple of weeks, I'm going to buy one of those infared laser thermometers and see if the front brake rotors are heating up at all when I press the pedal just enough to get the additional regen using D mode - If the brakes get hot, then it's a fact that we're also using the service brakes to slow the car, and not regen alone. Mitsu says they have "linked the use of the ordinary service brakes with additional regenerative braking" and I believe them. I think pressing the brake pedal always gets you some amount of friction to go with the regen, but just like everyone else's observations, this is more opinion than fact at this point

Don

 

[PV1]

There is a potentiometer on the brake pedal, coupled with a switch for the brake lights. This "pot box" maxes out right about where the friction brakes start kicking in. Sorry I missed it before. This also controls the point where the creep kicks out.

There is a tiny amount of friction brakes in the brake pedal regen range, barely enough to hold the car stopped on a slight incline in neutral. Of course, your cars may be calibrated differently (different brake pad/rotor sizes).