Dec 17

Finding the Volt’s Traction Motor Redline

 

DashDAQ discovers an interesting EV Operating mode

 

By George S. Bower
 

We all know that the Volt has two electric motors. These motors are blended to ensure efficient operation and so we don’t have any “overspeed” issues associated with having just one motor. Some may remember that the Tesla Roadster, during development, was originally supposed to have a 2-speed gearbox to help with motor overspeed issues. However, mechanical problems with this 2-speed box resulted in production delays and eventually the 2-speed box was eliminated and Tesla went with a custom, high rpm, hand wound motor eliminating need for the 2-speed gearbox.
 


 

What RPM limits do the Volt’s motors have?

I remember early forum discussions on this subject. Shortly after power split was announced, we speculated that the 70 mph transfer to power split was enacted because, at this speed, the main traction motor hit its redline at 6,200 rpm. (Also noted was the Prius 6,000 rpm limit.)

But how does the Volt really operate? When does it use one motor and when does it use two motors? Typically we would think that at lower speeds the Volt would be in one motor and at speeds above 70 mph it would be in two motor.

Much to my surprise and discovered using my newly acquired DashDAQ, under full throttle, the Volt stays in one motor operation ALL THE WAY TO 102 MPH! (Which is max governed speed.)

Discussion
 


 

Figure 1 shows the 4ET50’s planetary gear set configuration during one motor operation. In this mode, clutch 1 is closed locking the ring gear to ground and there is a single 3.24/1 gear reduction between the traction motor and the output (carrier) of the PG set.
 


 

Figure 2 shows the 4ET50’s configuration during two motor operation. Clutch 1 is disengaged and MGA blends to decrease MGB’s speed and allow efficient operation.

Volt Stays in 1 Motor Mode during Maximum Acceleration
 


 

The data taken with DashDAQ during max accel is presented in figure 3. The accelerator pedal was pushed to the floor. There are 2 very interesting things to note from this data:

1) The Volt stays in 1 motor mode all the way to 102 mph where MGB rpm hits 9,465 rpm …way in excess of the previously speculated 6,200 rpm limit.

2) Looking at the HV battery output, we see a fairly slow (1.2 second) ramp up to full power. Others (like DonC) have speculated about this “torque
softening” feature and, as we see here, it does exist. Taking some of this torque softening away could be a source of easily attained performance uprate for ELR or Volt SS models.

Volt shifts to 2 Motor after slowing to 60 MPH and holding Constant Speed
 


 

Following the accel, I slowed to the speed limit and held approximately 60 MPH on the flat and level road. Under these conditions, the Volt shifted to 2 motor operation. The shift is shown in figure 4.

The associated motor speeds for the 1 motor full accel and 2 motor steady state 60 mph condition are shown in figures 5 and 6.
 



 

Summary

Under full throttle the Volt stays in single motor and at steady state cruise it shifts to 2 motor operation. I can only speculate on the reason why the Volt operates this way:

During maximum acceleration we want maximum torque and this is provided by the 3/1 gear reduction of the sun/carrier speeds (versus the only 1.4/1 gear reduction of the ring/carrier speeds).

During steady state cruise we want “efficiency.” Maximum efficiency is attained by matching the motors at their most efficient operating point by “mixing” the two motors.

… What are your thoughts?

This entry was posted on Monday, December 17th, 2012 at 5:55 am and is filed under General. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.

COMMENTS: 52


  1. 1
    nasaman

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    Dec 17th, 2012 (7:14 am)

    “Much to my surprise and discovered using my newly acquired DashDAQ, under full throttle, the
    Volt stays in one motor operation ALL THE WAY TO 102 MPH! (Which is max governed speed.)”

    A brilliantly-written technical discovery/expose’, George! I’m also surprised to learn that MGB reaches 9,465 rpm at 102 mph vehicle top speed! It’s lead articles like today’s that make me feel especially privileged to learn from you, Jeff & the many other remarkably talented contributors here!


  2. 2
    jeffhre

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    Dec 17th, 2012 (7:15 am)

    One motor and a 1.2 second soft power ramp up? Time for an SS upgrade kit, RIGHT NOW!

    The efficiency is great, although…Two motors and no lag in power application would create one hot beast of a Volt!


  3. 3
    James McQuaid

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    Dec 17th, 2012 (7:28 am)

    George, this is absolutely outstanding:

    The data taken with DashDAQ during max accel is presented in figure 3. The accelerator pedal was pushed to the floor. There are 2 very interesting things to note from this data:

    “1) The Volt stays in 1 motor mode all the way to 102 mph where MGB rpm hits 9,465 rpm …way in excess of the previously speculated 6,200 rpm limit.

    2) Looking at the HV battery output, we see a fairly slow (1.2 second) ramp up to full power. Others (like DonC) have speculated about this “torque
    softening” feature and, as we see here, it does exist. Taking some of this torque softening away could be a source of easily attained performance uprate for ELR or Volt SS models.”

    I very much appreciate the superlative technical contributions that George Bower brings to this forum on a daily basis!


  4. 4
    Frank

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    Dec 17th, 2012 (7:49 am)

    Perhaps the 1.2 second ramp is to lessen the blow to the drivetrain. It seems that the Tesla Roadster transmission designers (even the big name companies) could not mass produce a transmisson that could survive to instant extreme torque that an electric motor can produce. Watch how quickly a tablesaw or router can go from 0 rpm to maximum, then imagine the loaded weight of a car againist even more torque.


  5. 5
    usaisgreat

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    Dec 17th, 2012 (7:49 am)

    Outstanding work, both in the diagrams and use of the DashDAQ. It is great to see how the 2Motor function will kick in when the VOLT determines the highest efficiency to run in (not a given 70 mph for instance). Nice job showing the max single motor rpm and also the ramp up rate which shows why after launch a VOLT is able to out run most cars and trucks.


  6. 6
    JDan

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    Dec 17th, 2012 (8:50 am)

    Frank: Watch how quickly a tablesaw or router can go from 0 rpm to maximum, then imagine the loaded weight of a car againist even more torque.

    Oooh, inline motors for the ELR! OK, probably not practical, but boy what a kick in the pants that would be. :D


  7. 7
    Loboc

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    Dec 17th, 2012 (9:11 am)

    Given the reverse and direct engineering presented in this forum, I expected this behavior. If you went into power-split too early, maximum power output would be limited by mga. In this pedal-to-the-metal mode, we may need more power from the engine (via mga through generation) to maintain power to 100mph.

    One of the car mags has shown that at minimum SOC, Volt accelerates slightly quicker because the ICE is generating power. Be interesting to test using hold mode.

    Nice presentation George!


  8. 8
    kdawg

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    Dec 17th, 2012 (9:19 am)

    I was hoping for a video :D


  9. 9
    KUD

     

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    Dec 17th, 2012 (9:32 am)

    kdawg:
    I was hoping for a video

    kdawg,

    Now that would be an awesome Video :)


  10. 10
    George S. Bower

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    Dec 17th, 2012 (9:36 am)

    kdawg:
    I was hoping for a video

    Yeh a video of me getting pulled over and hauled off to jail for going 102 MPH in a 75MPH zone!!


  11. 11
    Loboc

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    Dec 17th, 2012 (10:10 am)

    George S. Bower: Yeh a video of me getting pulled over and hauled off to jail for going 102 MPH in a 75MPH zone!!

    Lol. 102mph is SLOW!!

    Um.. Yeah officer, I was testing the EV with this new meter and it kinda got away from me.


  12. 12
    Jackson

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    Dec 17th, 2012 (10:23 am)

    Frank is correct.

    SS or no, there will always need to be some kind of “acceleration softening” in an EV of any reasonable power, to prevent snapping motor and tranny shafts like twigs. That’s not to say you couldn’t use less “softening” in some hotter GT, but this would likely be expensive in terms of more robust drivetrain components, at least. Sorry, I don’t think there will be an upgrade kit.


  13. 13
    RobbertPatrison

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    Dec 17th, 2012 (10:25 am)

    Thanks! Very nice to have the drive mode operation verified by data. The main things that puzzles me is the torque softening. Can you find out whether there is a difference between sport mode and normal mode, or is sport mode only a remapping of the pedal-to-throttle behaviour? I presume that thuis is not a measuring slowness artefact from the DashDAQ.

    If the 1.2s torque softening remains the same in sport, its interesting to speculate why it was set this slow:
    to reduce stress on the battery, stress on the power electronics, stress on MGB, stress on transmission or stress on tires to avoid traction control from kicking in all the time. Which of these is the dominating one? I understand that it needs some softening, it it seems that 1.2s is a little conservative.

    Or is this a marketing-driven derating, allowing the Cadillac to get better numbers using the same hardware. Or is overly good acceleration bad for the ECO-friendly image of an EV?


  14. 14
    Raymondjram

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    Dec 17th, 2012 (10:39 am)

    I recommend going to an unused airport strip to do acceleration and top speed runs on the Chevy Volt. That is what many car fanatics do, including the Mythbusters.

    One item that should be measured is the motor temperature during that run. I know that GM will not allow the maximum temperature to exceed design ratings, and if needed, just pipe in a CO2 extinguisher to cool the motor coolant through its radiator, and make the run again. Do the first run on a very cold day (cold wire has less resistance) but keep the battery warm.

    Raymond


  15. 15
    George S. Bower

     

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    Dec 17th, 2012 (10:42 am)

    RobbertPatrison:
    Thanks! Very nice to have the drive mode operation verified by data. The main things that puzzles me is the torque softening. Can you find out whether there is a difference between sport mode and normal mode, or is sport mode only a remapping of the pedal-to-throttle behaviour? I presume that thuis is not a measuring slowness artefact from the DashDAQ.

    If the 1.2s torque softening remains the same in sport, its interesting to speculate why it was set this slow:
    to reduce stress on the battery, stress on the power electronics, stress on MGB, stress on transmission or stress on tires to avoid from kicking in all the time. Which of these is the dominating one? I understand that it needs some softening, it it seems that 1.2s is a little conservative.

    Or is this a marketing-driven derating, allowing the Cadillac to get better numbers using the same hardware. Or is overly good acceleration bad for the ECO-friendly image of an EV?

    Excellent points.
    The data was taken in sport mode. The dashDAQ takes data every millisecond so I am assuming it has rhe response rate to capture what is going on in real world.

    Also as you say how much can the stock electronics and 4ET50 drive train take?? I have asked WOT about the 4ET50′s power/torque limit but I get no answer (it’s a secret)……but we shall find out when ELR comes out. Perhaps some material changes in the box will be enough (or non at all). And what changes in the power electronics???

    My guess is that GM built some growth capabilities into the electronics on purpose.


  16. 16
    Logical_Thinker

     

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    Dec 17th, 2012 (10:46 am)

    Your X-Y zero points are off, or else it took 14 seconds to accel to 60 mph.
    Also this observation shows that the motor RPMs are about 1600 RPM LESS than was concluded, or topping out around 7,865 RPM. (estimated from looking at graph tick marks. BTW, tick marks for mph don’t make 5/10 mph progression.)

    It sounds like you started from zero mph at zero seconds but the graphs suggest an initiation of data gathering somewhere around 15 mph at 7 seconds.

    Apart from the graphing errors, nice work.


  17. 17
    DonC

     

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    Dec 17th, 2012 (10:47 am)

    Great article George. The two motor “virtual gear” has been much discussed in the forums. I think our resident guru on the subject is saghost. One interesting finding has been that, when the virtual gear is operative, the main motor more or less holds the sun gear at almost a fixed position and the smaller motor turns the ring gear. Another has been that, as you’ve pointed out, the virtual gear is operative at lower speeds so long as those speeds are constant.

    Frank: Perhaps the 1.2 second ramp is to lessen the blow to the drivetrain.

    I’m thinking it’s more a tire issue. When discussing the tires on the Spark EV the GM folks have mentioned that they now have tires which give full performance and are low rolling resistance. If true those tires may allow for faster 0-60 MPH performance, though in practice the Volt is quite quick and acceleration is more than adequate.


  18. 18
    Steve

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    Dec 17th, 2012 (10:49 am)

    jeffhre:
    One motor and a 1.2 second soft power ramp up? Time for an SS upgrade kit, RIGHT NOW!

    The efficiency is great, although…Two motors and no lag in power application would create one hot beast of a Volt!

    Sure, eliminate the soft power ramp up and increase the risk of breaking things from the shock load. It might be time for some to consider that while they are drag racing and weaving in an out of traffic others have to hit their breaks and otherwise be annoyed. More power is too often used to get into more trouble, not out of trouble.


  19. 19
    George S. Bower

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    Dec 17th, 2012 (10:53 am)

    nasaman,

    Thx nasaman. Probably the best compliment I will receive in a lifetime.


  20. 20
    George S. Bower

     

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    Dec 17th, 2012 (10:54 am)

    Raymondjram:
    I recommend going to an unused airport strip to do acceleration and top speed runs on the . That is what many car fanatics do, including the Mythbusters.

    One item that should be measured is the motor temperature during that run. I know that GM will not allow the maximum temperature to exceed design ratings, and if needed, just pipe in a CO2 extinguisher to cool the motor coolant through its radiator, and make the run again. Do the first run on a very cold day (cold wire has less resistance) but keep the battery warm.

    Raymond

    Raymond,
    just checked but unfortunately motor temp is not available.


  21. 21
    Jim_NJ

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    Dec 17th, 2012 (11:01 am)

    jeffhre: Time for an SS upgrade kit, RIGHT NOW!

    Thanks for this incredibly informative post George.

    And I concur with jeffhre – Time for an SS upgrade kit, RIGHT NOW! I really hope that GM fixes the ‘torque softening’ at launch for 2014. Does anyone have any idea why this was done? Tesla doesn’t seem to have this problem. The Tesla-powered RAV4-EV can blow the doors off my Volt, even though the RAV4′s motor is almost identically spec’d to the Volt’s (although the RAV 4 has a lower weight, it has more aerodynamic drag which is probably a wash).

    I have always suspected that something like this blended-motors-at-speed setup was happening because when I floor it to pass someone on the highway there is a 1/2 – 1 second pause before my Volt accelerates. I always figured that this pause is caused by the de-coupling of clutches.

    But what had me perplexed is that sometimes I would floor it to pass, and the Volt would respond immediately. I did notice that this would happen before I had settled down to a cruising speed – and now I know why! Thanks!


  22. 22
    Raymondjram

     

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    Dec 17th, 2012 (11:03 am)

    George S. Bower,

    I know that there must be a temperature sensor for the motor coolant. Maybe the OBD port might not allow an external reading but if the sensor can be reached, its values can be measured. I don’t have a Volt or any manuals so I don’t know where it is, but it could be attached to the radiator.

    Raymond


  23. 23
    George S. Bower

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    Dec 17th, 2012 (11:03 am)

    Logical_Thinker:
    Your X-Y zero points are off, or else it took 14 seconds to accel to 60 mph.
    Also this observation shows that the motor RPMs are about 1600 RPM LESS than was concluded, or topping out around 7,865 RPM. (estimated from looking at graph tick marks. BTW, tick marks for mph don’t make 5/10 mph progression.)

    It sounds like you started from zero mph at zero seconds but the graphs suggest an initiation of data gathering somewhere around 15 mph at 7 seconds.

    Apart from the graphing errors, nice work.

    If you re look at the graph it took 7.5 seconds to go from 12-60 MPH (I started taking data from a rolling start).

    Also the max motor speed is 9400 RPM since each ss division is 400 RPM.


  24. 24
    mfennell

     

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    Dec 17th, 2012 (11:04 am)

    Great stuff George. Thanks!

    I agree with Robbert that 1.2s seems far too conservative to serve a longevity purpose.

    Aside from the possibility of a market-driven derating Robbert suggests, maybe it serves as a passive traction control. That is, if you ramp up torque smoothly over a period of time, you’re less likely to engage active traction control. As it is, I often spin the inside wheel a little when accelerating/turning into traffic from a standstill.


  25. 25
    stuart22

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    Dec 17th, 2012 (11:15 am)

    Great post George. The deeper one looks, the clearer the brilliance of the design becomes. A full spectrum of performance/efficiency available via software changes – the simplicity of it all excites the imagination. Now all we need is for battery technology to catch up – greater range, faster recharging, lower costs – then EVs will take over and rule the automobile world.


  26. 26
    Jackson

     

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    Dec 17th, 2012 (11:26 am)

    I doubt that GM intentionally padded the ‘softening’ to deliberately slow the car compared to later offerings; at least not as a primary consideration. The Volt was a significant gamble, and I think GM did shoot for the “sweet spots,” including 40 miles range, for example (serving the needs of around 70% of commuters according to DOT figures at the time). There was great concern over the health of the battery pack at first, which was treated with kid gloves in the initial Volt offering (with real on-the-road data to reassure them, they decided to loosen up a bit later). The conservative acceleration softening probably reflected a balance between battery-based caution and performance. Also, the selected acceleration times were at least comparable to some examples of equivalent ICE cars.

    That said, if Bob Lutz was involved (and he was ;-) ), there probably is a ready path to greater performance; and there might be a flash possible which would reduce the acceleration padding a bit (though not as much as a designed-for-SS model).


  27. 27
    pjkPA

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    Dec 17th, 2012 (11:55 am)

    Very good article George!

    Real world experiences are what make me come back to this site… Thanks for taking the time to create this article.

    I may have talked myself into leasing a Volt… then buy the MPV5 when it comes out.


  28. 28
    Shaft

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    Dec 17th, 2012 (12:24 pm)

    Great data!

    Perhaps you can do the following test:
    1. Travel a bit at 60mph to be in 2 motor mode.
    2. Floor the accelerator.
    3. Take the same measurements as you have.

    I notice a slight pause as the car shifts to one motor operation. I’d like to see the data behind it.


  29. 29
    Noel Park

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    Dec 17th, 2012 (12:32 pm)

    George S. Bower: Yeh a video of me getting pulled over and hauled off to jail for going 102 MPH in a 75MPH zone!!

    #11

    Well at least it doesn’t make a bunch of noise to attract the cops, LOL. “Stealth drag racer”.

    Nice article. Thanks. +1


  30. 30
    George S. Bower

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    Dec 17th, 2012 (12:35 pm)

    Noel Park: #11

    Well at least it doesn’t make a bunch of noise to attract the cops, LOL.“Stealth drag racer”.

    Nice article.Thanks.+1

    Actually it was posted 55 MPH. But it seemed such a flagrant violation I changed it to 75.


  31. 31
    Noel Park

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    Dec 17th, 2012 (12:36 pm)

    Frank:
    Perhaps the 1.2 second ramp is to lessen the blow to the drivetrain.It seems that the Tesla Roadster transmission designers (even the big name companies) could not mass produce a transmisson that could survive to instant extreme torque that an electric motor can produce.Watch how quickly a tablesaw or router can go from 0 rpm to maximum, then imagine the loaded weight of a againist even more torque.

    #4

    No doubt. +1

    That’s one thing you learn from racing. Warm up the engine, break the clutch. Beef up the clutch, break the gearbox. Beef up the gearbox, break the drive shaft. Beef up the drive shaft, break the rear end. Beef up the rear end, break an axle.

    Put on stickier tires to stop the wheelspin, start the process all over, LOL.


  32. 32
    Logical_Thinker

     

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    Dec 17th, 2012 (12:37 pm)

    @George S. Bower… ok cool…
    Is there a reason you started recording after driving for a few seconds? Just curious.
    Would it have changed the results to record starting from zero mph?


  33. 33
    RobbertPatrison

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    Dec 17th, 2012 (12:44 pm)

    I suspect that the main reason for the ‘torque softening’ 1.2s ramp-up to full power is mainly to reduce mechanical stress on the gears and tires. I’d imagine that GM fears that many people are in the habit of flooring the pedal at every traffic light, and the 5 year drivetrain warranty might be at risk with wear due to higher torque stress levels. I think they considered the feel already sufficiently dynamic with this more conservative setting. And the gain in 0-60 numbers is probably limited. The Volt is not marketed as a sports car anyway.

    Another concern is the increased risk of spinning wheels and traction control uncomfortably kicking in to fight that. One would imagine that with a lane-departure camera and other sensors, it would be possible to better guess the max torque the road can handle.

    Parameters like this torque damping were extensively simulated during the design phase by the engineers. Those computer models are good at predicting the speed and dynamic behaviour. But impact on reliability and time-before failure is always a little vague, so general tendency is to be conservative. And they want to have the option of using cheaper grades of steel or bearings in mass production. There were multiple reports of Volts with broken gear bearings due to a plastic ball spacer, so it seems GM went a little too cheap there.


  34. 34
    Streetlight

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    Dec 17th, 2012 (12:44 pm)

    George S. Bower,

    First, higher speed motors are more efficient than those lower speed. Secondly, a balance must be ensured between I^2R losses and motor temp rise. Plus, two motors (I think) will improve brake regeneration. Its pretty much about motor temp. vs I^2R distribution. Which equates to efficiency and overall reliability.

    A very well done presentation.


  35. 35
    George S. Bower

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    Dec 17th, 2012 (12:45 pm)

    Noel Park: #4

    No doubt.+1

    That’s one thing you learn from racing.Warm up the engine, break the clutch.Beef up the clutch, break the gearbox.Beef up the gearbox, break the drive shaft.Beef up the drive shaft, break the rear end.Beef up the rear end, break an axle.

    Put on stickier tires to stop the wheelspin, start the process all over, LOL.

    Well that’s it. Motorhead quote of the day goes to Noel.


  36. 36
    George S. Bower

     

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    Dec 17th, 2012 (12:46 pm)

    Logical_Thinker:

    Is there a reason you started recording after driving for a few seconds?

    Yes I didn’t want to get a ticket.


  37. 37
    BLIND GUY

     

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    Dec 17th, 2012 (2:16 pm)

    I agree with #33 RobbertPatrison. I confess that I am concerned about the bearing issue that some Volt owners have experienced. It is probably a good thing that my wife is the driver because I would probably drive more aggressively on reaching the speed limits to enjoy the torque. I am hoping that the failed bearings were a fluke and not a weak link; not up to the task. We both love our Volt, so far and are expecting drive-train parts to not wear out with “normal” driving. Thanks George, I always enjoy learning more about EVs and the Volt in particular.


  38. 38
    Frank

     

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    Dec 17th, 2012 (2:29 pm)

    Thanks for the pluses!
    @Noel, I grew up in a racing family and also understand the fun (expense!) of more hp/torque and sticky tires! Stock components are not up to the task of the repeated instant shock available from electric motors. As a racer/electrical engineer it is understandable what G.M. has done here.
    Not to threadjack this section but to see whats (Watts?) available look up White Zombie electric car or Megacycle on youtube. You won’t believe your eyes!


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    kdawg

     

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    Dec 17th, 2012 (2:31 pm)

    George – can you use your DashDAQ to chart the kW vs speed? It would be interesting to see the difference between 2 motor mode and 1 motor mode around the 60mph mark. I have started collecting some data using the kW display on my 2013 Volt, but I don’t think it is as accurate as your DashDAQ. I am trying to compare the kW used at steady state in various speeds as well.


  40. 40
    Loboc

     

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    Dec 17th, 2012 (2:58 pm)

    Jackson: Frank is correct.

    SS or no, there will always need to be some kind of “acceleration softening” in an EV of any reasonable power, to prevent snapping motor and tranny shafts like twigs.That’s not to say you couldn’t use less “softening” in some hotter GT, but this would likely be expensive in terms of more robust drivetrain components, at least.Sorry, I don’t think there will be an upgrade kit.

    If you used the parts from a truck, say a model 5 CUV, they would stay together longer under stress. Even so, a full second is way too much. The power could be controlled just under breakage using the computer controls less conservatively. 273lbft is just not that much. It’s V-6 torque range. (8.5 – 1.2 is 7.3 seconds 0-60.) The main problem is that there is no torque converter to soften the blow.

    Since Volt was built to be a Prius killer, not a Camaro killer, I can see the tradeoffs.


  41. 41
    pjwood

     

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    Dec 17th, 2012 (3:25 pm)

    As the Volt is a car with a lot of crossover buyers, I wonder if more aren’t actually put off by the throttle response we now recognize as dialed out. Hybrids get enough flak from inconsistent braking. 1.2 seconds is a heap of time, if we’re getting sporty. Maybe less is in order?

    I’ve had the car in 30-40mph turns, where it holds the front end to the road under full throttle, where I would have had understeer without the pedal. It’s delightful, with the low CG and all, but truthfully you need to plan your line and get on the pedal early if you want to tap into its maximum exit speed. Being able to (rarely/safely) have this type of experience is why so many (mostly guys) put up with cars that are otherwise completely inappropriate in stop-and-go traffic.


  42. 42
    George S. Bower

     

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    Dec 17th, 2012 (3:47 pm)

    kdawg,

    kdawg.jpg

    This is the accel. The steady state plot doesn’t mean much since it is at a constant speed


  43. 43
    Jeff

     

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    Dec 17th, 2012 (4:14 pm)

    The power/torque limiting is very interesting info. The 1.2 seconds that it takes to ramp up to full power is a lot FASTER than I had expected based on the power displays on the 2013 models.

    According to the DIC power displays on my 2013, when flooring the accelerator, it doesn’t show full power until I hit about 40mph. So that’s more like 4-5 seconds! So Assuming that the DashDAQ is getting accurate numbers, that’s a HUGE delay in the DIC power display!

    Anyone have any theories on why this would be?


  44. 44
    kdawg

     

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    Dec 17th, 2012 (4:16 pm)

    George S. Bower:
    kdawg,

    This is the accel. The steady state plot doesn’t mean much since it is at a constant speed

    Interesting that the power goes DOWN from 35 mph up to 100 mph. Did you chart the deceleration when you crossed over 60 mph? Would you guess the power would remain at 100kW to maintain 100mph?

    This is what I have so far regarding my “steady state” data collection and adding your 100mph info:

    KWvsSPEED_zps1983b1e9.jpg


  45. 45
    haroldC

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    Dec 17th, 2012 (5:16 pm)

    Noel Park,

    You missed one Noel……Fix everything so it don’t break……..break your wallet……lol

    Been there…done that….lol

    Thanx to George…great article…+1

    haroldC


  46. 46
    Noel Park

     

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    Dec 17th, 2012 (5:22 pm)

    pjwood: As the Volt is a car with a lot of crossover buyers, I wonder if more aren’t actually put off by the throttle response we now recognize as dialed out. Hybrids get enough flak from inconsistent braking. 1.2 seconds is a heap of time, if we’re getting sporty. Maybe less is in order?

    #41

    I have over 34K miles on my Volt and I have NEVER even noticed this phenomenon. And I’m a fairly sporty driver, at least sometimes. But to me the Volt is more about maximizing AER and gas mileage, so I VERY rarely mat the throttle.

    I’m thinking that most people who consider a Volt think pretty much the same way. So I seriously doubt that this is putting off many buyers.

    Maybe this is a business opportunity for the aftermarket computer “reflash” artists. But I sure wouldn’t let them anywhere NEAR my Volt, LOL.

    Plus, I don’t have any problem with the brakes. As I’ve said do many times, after road racing an old Corvette with the original drum brakes, the brakes on my volt make me feel like I’m in a F1 car, hahaha.


  47. 47
    Noel Park

     

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    Dec 17th, 2012 (5:28 pm)

    haroldC: You missed one Noel……Fix everything so it don’t break……..break your wallet……lol

    Been there…done that….lol

    #45

    You got that right, LOL. +1

    “The way to make a small fortune out of racing – start with a large one.”

    When things go rat s__t I console myself by remembering that Toyota reputedly spent $1.5 BILLION on their recent F1 effort and never won a race. And Honda’s last go around wasn’t much better. Nobody’s perfect.


  48. 48
    Raymondjram

     

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    Dec 17th, 2012 (6:31 pm)

    Loboc:
    Since Volt was built to be a Prius killer, not a Camaro killer, I can see the tradeoffs.

    Why should it kill its own Chevy brother? Maybe the Volt is a Ferrari killer!

    Raymond


  49. 49
    Larry4pyro

     

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    Dec 17th, 2012 (8:35 pm)

    I think I understand the 1.2 second ramp up, it reduces stress on the gear train, but it would be nice if the driver is given an option to select a slightly faster ramp up in Spot mode.

    Do you think it could be possible to go to a temporary over boost condition where the inverter sends extra power for a few seconds?


  50. 50
    jeffhre

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    Dec 18th, 2012 (12:16 am)

    Steve: Sure, eliminate the soft power ramp up and increase the risk of breaking things from the shock load. It might be time for some to consider that while they are drag racing and weaving in an out of traffic others have to hit their breaks and otherwise be annoyed.More power is too often used to get into more trouble, not out of trouble.

    Are you saying Volt drivers are irresponsible :) There are a number of vehicles that have over 500 hp on the roads today. Yep, I know crazy irresponsible. But somehow those folks seem to to get to work and back home OK. Maybe I’m just overreacting and getting the folks who can afford ZL1′s, AMG’s, M series, Cobras and the like confused with reckless teens, dunno just a thought.


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    jeffhre

     

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    Dec 18th, 2012 (12:23 am)

    Jim_NJ: And I concur with jeffhre – Time for an SS upgrade kit, RIGHT NOW! I really hope that GM fixes the ‘torque softening’ at launch for 2014. Does anyone have any idea why this was done? Tesla doesn’t seem to have this problem.

    In an effort at full disclosure…Tesla broke a whole lot of stuff before they got it right. Ever seen a CEO give an ABC news reporter a ride in new Roadster, go really fast, then clunk clunk stop, on national TV? Not a fun day :(


  52. 52
    Ricardo

     

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    Dec 18th, 2012 (11:07 pm)

    here is a video showing the two motors during acceleration and cruise (MGA on the left and MGB on the right)

    http://www.youtube.com/watch?v=BhB-cgfNCWk

    enjoy.