Regen - does higher B make acceleration less efficient?

[sheselectric]

I may have missed the answer to this already, but my question is,
Does driving in b5 make driving less efficient? - if in b5 are you accelerating against friction, if that's the term?
A colleague drives in b5 to get most from regen, but I've been driving in b0 and using paddles as need be, on the belief that driving in b0 means I have to push less hard on the accelerator for the same return.
Is there a clear answer here?
Thanks

 

[jaapv]

Simple answer - no.
Regen has only to do with the power generated by the electric motors acting as generators on the overrun.

 

[Stvtech]

Personally, I believe driving in B5 would be far less efficient.

The car will not be accelerating against friction because the 'friction' that you feel is, as Jaap points out, only present when the motors are acting as a generator.

You are however, losing momentum each time you lift of the throttle, and will require more energy than has been recovered by the regen, to get that momentum back.

 

[discorduk]

You are however, losing momentum each time you lift of the throttle, and will require more energy than has been recovered by the regen, to get that momentum back.

Depends how lightly you use the throttle.

I have an advantage here because i use hand controls so can apply a very light touch and consistently, but from watching the power distribution diagram and the usage dial i have noticed a few things...

I drive on B5 a lot, and especially when going downhill I have noticed that if you use very light accelerator it is the same as using a lighter B setting, as it shows power from wheels to battery and the needle only slightly in the regen range, the harder you press the accelerator the lighter it gets until theres no flow, and eventually starts adding speed when the power flow flips. Which makes sense from what i remember of motor/generator theory, if you put in as much electricity as it generators (ie short it out) it freewheels, and as you take more of that electricity away the resistance increases.

There is also a B6 equivalent, which it never mentions, but very light braking pushes the regen-o-meter even deeper into charging territory than is achievable through the paddles alone.

 

[jaapv]

Yes - but there will always be inevitable conversion losses associated with converting motion to electricity and back again.

 

[kentphev]

IMO Its *much* easier to coast in B0 than B5. Therefore for the majority of people Id suggest staying in B0 and keeping the maximum forward momentum is going to be more efficient in the long run.
I only flick up to higher levels:

1. to control speed on a steep hill
2. on approach to something that requires me to slow, eg junction
3. in start/stop traffic

But you do harvest a lot more energy when braking in B5, so you really do want to be using the paddles. Also gives you something to do since there are no gears

 

[PeterGalbavy]

My completely non-scientific experience so far is to leave the car in "D" mode for normal city driving, B0 when on a long road and you can take your foot off the accelerator - the car is heavy enough to keep going at speed without any need for power - and then I use the paddles for engine breaking down hills based on the incline - setting the B level to maintain the speed limit. Living in North London there are plenty of hills - power used up, may as well get some back coasting down.

 

[karl]

I drive on B5 a lot, and especially when going downhill I have noticed that if you use very light accelerator it is the same as using a lighter B setting, as it shows power from wheels to battery and the needle only slightly in the regen range, the harder you press the accelerator the lighter it gets until theres no flow, and eventually starts adding speed when the power flow flips. Which makes sense from what i remember of motor/generator theory, if you put in as much electricity as it generators (ie short it out) it freewheels, and as you take more of that electricity away the resistance increases.

There is also a B6 equivalent, which it never mentions, but very light braking pushes the regen-o-meter even deeper into charging territory than is achievable through the paddles alone.

I think that changing from B0-B5 just moves the the zero-position and the "regen-window" on the brake-accelerator axis, and it's a programmed effect rather than a "simple" function of the input current.

Not regarding the situation when stopped; Over a certain speed the B0 position is just that - no regen or no motor force on the "zero" position: no accelerator or brake input.
Each step towards B5 moves the "neutral" position further down on the accelerator.

You can test this by keeping the throttle steady in B5 and step down to B0 while watching the power meter. For each step, the power meter will actually increase and the car will accelerate - also on a level road.
Also try this: While braking lightly in B0, change gear into neutral (by holding the stick in N for a few seconds) and notice that most if not all brake force disappears - ie the mechanical brake isn't really applied much, it's just the regen that sets in.

So light to moderate braking in B0 does quite some regen, but I use the paddles anyway since then I'm certain that the energy is not wasted - plus it's fun.

At low speeds, the "window" is moved slightly as well, to get the artificial "crappy worn out gearbox pull", but the effect fans out over a certain speed.
If you let the car come to a (slow) stop by just idling, I think it's almost possible to feel the increased motor output and it's marginally visible on the power meter.

If there was ONE modification I'd really like, it would be to disable the idle-pull. It really only makes the car jittery and fighting the brakes when maneuvering in parking lots and I really hate it.

(...some pongs, beeps and chimes could go too... And maybe make the transitions between the B-levels a bit smoother.
Oh! And the car should totally have been about 11% wider. It had both looked great, and the middle seat almost usable.)

 

[jaapv]

If you apply the brakes more firmly when standing the power to the motors will switch off.
Have you noticed that you can flick from R to D and back quite smoothly at low speeds without touching the brake making maneuvering very simple?

 

[Stvtech]

I drive on B5 a lot, and especially when going downhill I have noticed that if you use very light accelerator it is the same as using a lighter B setting, as it shows power from wheels to battery and the needle only slightly in the regen range, the harder you press the accelerator the lighter it gets until theres no flow, and eventually starts adding speed when the power flow flips. Which makes sense from what i remember of motor/generator theory, if you put in as much electricity as it generators (ie short it out) it freewheels, and as you take more of that electricity away the resistance increases.

There is also a B6 equivalent, which it never mentions, but very light braking pushes the regen-o-meter even deeper into charging territory than is achievable through the paddles alone.

I think you messed up your quotation tags there karl, as that was discorduk who said that, not me - I never leave it in B5 !!

I think that changing from B0-B5 just moves the the zero-position and the "regen-window" on the brake-accelerator axis, and it's a programmed effect rather than a "simple" function of the input current.

I think I can see your logic there, because at higher B settings you don't need to lift all the way of the throttle to experience deceleration.
I don't agree however, with the suggestion (somewhere on here) that B0 feeds power into the motors to cancel out the deceleration caused by regen - I feel that B0 simply removes the load from the generators allowing them to freewheel.

Energy has to be converted from one form to another, and at B0, very little energy is being taken from the car's inertia (kinetic) so the car coasts for longer. Start increasing the B setting (and hence load on the generators) in order to convert to electrical current, and the energy has to come from the car's inertia and deceleration occurs.

 

[Kaboom]

I may have missed the answer to this already, but my question is,
Does driving in b5 make driving less efficient? - if in b5 are you accelerating against friction, if that's the term?
A colleague drives in b5 to get most from regen, but I've been driving in b0 and using paddles as need be, on the belief that driving in b0 means I have to push less hard on the accelerator for the same return.
Is there a clear answer here?
Thanks

Hi sheselectric,

Have yout tried this?:

Paddle down to B0
Find a level road
Drive at a constant 30mph (or similar)
watch the eco/power dial (needle should be steady)
Paddle up to B5 and the needle moves

Thanks!

 

[greendwarf]

As an experiment, for the last few days, I've been using the Regen via the gear stick in addition to the paddles, in the same way I would have used gears in the past.

I cruise mainly in B0 paddling up & down when freewheeling to tackle the mountains of Sarf Lundun. However, when coasting to a stop at the one or two traffic lights we have here, I find it easier to use the gear stick to go to B3 and then B5 rather than repeat flicking the paddles (and losing count!). I can then just move the stick across to D to hopefully move off as the lights change when I reach them.

It is probably just a coincidence but both predicted and actual EV range seem to have increased, at the same time :mrgreen:

 

[anko]

In B5 max regen capacity is bigger than it is in B0 (about 150 Amps or 50 kW max versus 90 Amps or 30 kW max). This means you may need to use the breaks more often, and thereby throw away more energy, as you cannot anticipate to everything.

It might also mean there is more wear to the battery in B5, as it gets bigger charge currents to deal with.

 

[deskry]

Wow there is some scary stuff being done by PHEV drivers here!! Changing from Drive to Reverse and back without coming to a halt on the footbrake like you would with a normal Auto! I think unless you really know the Engineering involved I would stick to the book. As to the original question, I think that has been answered. The regenerative braking only takes places when the 2 electric motors reverse modes to become generators (alternators) and that happens only when you take your foot off the accelerator. I know some auto gearbox drivers who swear by using both feet with an auto car (you should use only your right foot) With this baby you had better not carry over that habit as the foot brake also activates regeneration; you must not be touching the accelerator when you touch the footbrake pedal.

As to driving a lot in B5 to achieve best economy, I think not, no amount of fancy footwork will get you back the energy you expend accelerating unless you are on a specific journey from a high destination to a lower altitude one. I agree that B0 is best if the road is clear and straightish. I find D (or B2) to be a little more braking than my wife's Lancer petrol auto in Drive and I believe the 2016 models will activate the brake lights if lifting off the throttle in B4 & B5 (sensible). However it could do with a B6.

 

[ian4x4]

If you want the answer to the efficiency of continually regenerating B5 instead of coasting B0, please read the following technical description. About page 19 or so you will see that the minimum loss will be about 15% on every AC/DC cycle you go through.

https://dl.dropboxusercontent.com/u/106981165/PHEV/PHEV%20Outlander%20Technical%20Highlights%20for%20MMAL.pdf

I think the answer is to anticipate and coast like any car for the best efficiency.

 

[deskry]

ian4x4, your hyperlink to dropbox has a Error (400) displaying

 

[jaapv]

Wow there is some scary stuff being done by PHEV drivers here!! Changing from Drive to Reverse and back without coming to a halt on the footbrake like you would with a normal Auto! I think unless you really know the Engineering involved I would stick to the book. As to the original question, I think that has been answered. The regenerative braking only takes places when the 2 electric motors reverse modes to become generators (alternators) and that happens only when you take your foot off the accelerator. I know some auto gearbox drivers who swear by using both feet with an auto car (you should use only your right foot) With this baby you had better not carry over that habit as the foot brake also activates regeneration; you must not be touching the accelerator when you touch the footbrake pedal.

As to driving a lot in B5 to achieve best economy, I think not, no amount of fancy footwork will get you back the energy you expend accelerating unless you are on a specific journey from a high destination to a lower altitude one. I agree that B0 is best if the road is clear and straightish. I find D (or B2) to be a little more braking than my wife's Lancer petrol auto in Drive and I believe the 2016 models will activate the brake lights if lifting off the throttle in B4 & B5 (sensible). However it could do with a B6.

Don't worry, reversing polarity on an electric motor won't harm it. Flipping from Drive to Reverse and back is one of the nice features of the car.

 

[ian4x4]

Sorry

https://dl.dropboxusercontent.com/u/106981165/PHEV/PHEV%20Outlander%20Technical%20Highlights%20for%20MMAL.pdf

Try this

 

[deskry]

Ian4x4. Thanks; that is just what I was after. It confirmed a few things I learned myself that I have not seen in the Drivers Manual or on Mitsubishi's website.