tomrh
Posts: 33
Joined: Tue Jun 18, 2013 12:27 pm
Location: Norway

Re: Power appears to be dependent on regen mode

Thu Oct 17, 2013 2:50 pm

Malm, thank you for supporting my claim by measurements!

What siai47 says makes sense, but I experience that the power gauge jump is not followed by a speed change. My speed remains constant, only the power gauge changes. While power consumption is low and speed is high, as would be on a flat road, B seems to require less power than (european) D.

Tonight I drove 45 mph upwards a hill, and the power gauge was in the white area to keep that speed constant. I switched back and forth between D and B. And guess what, this time D displayed less power consumption than B. Both speed and pedal depth were constant during the "gear" shifts.

That makes me believe that (european) D is somehow optimized for high power driving and B is optimized for low power driving. I also experience that B and C (european Comfort mode) has the same pedal vs power characteristics except for regeneration where B has a lot and C almost nothing.
Black 2012 i-MiEV, 70k miles.
Black 2012 Leaf.

Malm
Posts: 449
Joined: Mon Jul 22, 2013 12:16 pm
Location: Tábua - Portugal

Re: Power appears to be dependent on regen mode

Thu Oct 17, 2013 3:25 pm

I confirm what tomrh says, the power gauge jump in not followed by a speed change. When we change to B, we don´t feel any kind of breaking, and the instrumentation confirm that. And the car just keep on going at the same speed.
Riding an i-Miev since 4/2011 in Portugal, 100.000 kms.

Don
Site Moderator
Posts: 2926
Joined: Thu May 10, 2012 3:55 pm
Location: Biloxi MS

Re: Power appears to be dependent on regen mode

Thu Oct 17, 2013 3:48 pm

Interesting

I've always felt that I go farther using 'B' mode all the time, but I assumed it was because I was using the brakes so little because I was using regen for slowing all the time, but now it appears there may be even more to it

Don
2012 iMiEV SE Premium, White
2012 iMiEV SE, White
2017 Chevy Volt Premier
2014 Ford Transit Connect XLT SWB wagon, 14,000 miles
1979 Honda CBX six into six

siai47
Posts: 363
Joined: Fri Jun 14, 2013 5:54 pm

Re: Power appears to be dependent on regen mode

Thu Oct 17, 2013 5:04 pm

We might be looking at apples and oranges between the calibration of the drive system in the European vs. US spec vehicles. I my US spec vehicle, without changing pedal postion, a shift from D to E will show a current reduction (as indicated by the dash gauge) and slow the car. Going from E to B will increase current and start to pick up speed. Going from D to B (or vise versa) shows no change in current or speed. Going from E to D will also increase current and start to pick up speed. That's what I have observed in both of my I-MiEV's. For urban driving I find the E (ECO) mode works out best for me, however like other posters, I would like more regen in ECO.

tomrh
Posts: 33
Joined: Tue Jun 18, 2013 12:27 pm
Location: Norway

Re: Power appears to be dependent on regen mode

Thu Oct 17, 2013 11:33 pm

That might be true, siai47. Eco seems to be completely different, we have no power restrictions on the european driving modes.

But dwelling at the measurements by Malm, is it really possible to optimize an electric motor within specific current ranges? In B mode it appears that engine losses are somehow minimized while drawing small currents. But this comes at the price of bad efficiency while drawing much higher currents. The opposite with european D-mode where low currents seems to have the lower motor efficiency. This mode is obviously meant for urban and "sports" driving with higher accelerations and decelerations.

Gasoline and diesel engines are different, diesel engines are more effective at lower rpm's. But even gasoline engines may be tuned to have very different efficiency curves vs rpm. As an example, my old Mitsubishi Spacewagon 2.4 GDI has a much higher torque and efficiency at lower rpm's than normal gasoline engines. Maybe we observe the same with i-MiEV - the driving modes are simply a selection of different tunings of an electrical motor?
Black 2012 i-MiEV, 70k miles.
Black 2012 Leaf.

Malm
Posts: 449
Joined: Mon Jul 22, 2013 12:16 pm
Location: Tábua - Portugal

Re: Power appears to be dependent on regen mode

Fri Oct 18, 2013 3:24 am

tomrh wrote:That might be true, siai47. Eco seems to be completely different, we have no power restrictions on the european driving modes.

But dwelling at the measurements by Malm, is it really possible to optimize an electric motor within specific current ranges? In B mode it appears that engine losses are somehow minimized while drawing small currents. But this comes at the price of bad efficiency while drawing much higher currents. The opposite with european D-mode where low currents seems to have the lower motor efficiency. This mode is obviously meant for urban and "sports" driving with higher accelerations and decelerations.

Gasoline and diesel engines are different, diesel engines are more effective at lower rpm's. But even gasoline engines may be tuned to have very different efficiency curves vs rpm. As an example, my old Mitsubishi Spacewagon 2.4 GDI has a much higher torque and efficiency at lower rpm's than normal gasoline engines. Maybe we observe the same with i-MiEV - the driving modes are simply a selection of different tunings of an electrical motor?



Tomrh, i´m following your findings and i'm amazed. Just keep going, i think you are going in the right path. Let me say you three sings: congratulations, congratulations and congratulations for your findings. I will support you with my data, if they confirm what you are reporting. Maybe tomorrow i can obtain some unambiguous graphs.
Riding an i-Miev since 4/2011 in Portugal, 100.000 kms.

tomrh
Posts: 33
Joined: Tue Jun 18, 2013 12:27 pm
Location: Norway

Re: Power appears to be dependent on regen mode

Fri Oct 18, 2013 6:25 am

Thanks, Malm. I must add that it was another Norwegian guy with nick "uppis" who initially discovered this. I followed his instructions and was pretty amazed. The i-MiEV continues to surprise me, there is always more to its inner workings than we think we already know. I do not know electric motors very well, but googling "electric motor tuning" brings forward many hits where racing enthusiasts give away tuning tips for maximizing power etc. And some say they use software for tuning. So some sort of built-in tuning profiles should be possible.

As I said I'm not at all into the inner workings of electrical motors, but I read somewhere that the magnetic field strength of the permanent magnet has a square impact. And then I thought of something. Could it be that some secondary current is used for increasing the strength of some magnetic field, which in turn would provide higher efficiency? The idea is that the european D mode would enable this current while B disables it. And at low power consumption this secondary current becomes significant, meaning D uses more power than B. Just a thought. Hopefully someone with a more profound knowledge of electric motors will comment on this thread.
Black 2012 i-MiEV, 70k miles.
Black 2012 Leaf.

NeilBlanchard
Posts: 356
Joined: Tue Jun 19, 2012 11:26 am
Location: Maynard, MA Eaarth
Contact: Website

Re: Power appears to be dependent on regen mode

Sat Oct 19, 2013 3:12 pm

Quick side note: the Smart Electric Drive has an option ($190) for paddles behind the steering wheel, that let you toggle between no regen, normal regen, and maximum regen. That's a no-brainer. Oh, and the lease is $2K down and $139/month for the base Smart ED. Heated seats are the other smart option...
Sincerely, Neil

http://neilblanchard.blogspot.com/

Malm
Posts: 449
Joined: Mon Jul 22, 2013 12:16 pm
Location: Tábua - Portugal

Re: Power appears to be dependent on regen mode

Sun Oct 20, 2013 1:22 am

"What siai47 says makes sense, but I experience that the power gauge jump is not followed by a speed change. My speed remains constant, only the power gauge changes. While power consumption is low and speed is high, as would be on a flat road, B seems to require less power than (european) D." tomrh, Oct 17.

"I confirm what tomrh says, the power gauge jump in not followed by a speed change. When we change to B, we don´t feel any kind of breaking, and the instrumentation confirm that. And the car just keep on going at the same speed." Malm, Oct 17.

Now in video:

http://www.youtube.com/watch?v=j-sKHw445XA
Riding an i-Miev since 4/2011 in Portugal, 100.000 kms.

ZsoZso
Posts: 12
Joined: Tue Oct 16, 2012 8:50 am
Location: Brampton, Ontario, Canada

Re: Power appears to be dependent on regen mode

Thu Mar 13, 2014 11:52 am

Malm wrote:Image


Do I interpret this graph correctly if I conclude that the max regen is only about 4.5kW (328V with -120A)?
That sounds very little compared to the Tesla Model S which has 60kW max regen.

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