how to disable the speed limiter

[pierred]

I'd like to take my lovely Spark EV for a spin around Sonoma Raceway, but that 90 MPH speed limiter is a royal pain in the butt!
Can it be removed / disabled / reset / overridden / defeated / obliterated ? (For off-road use only, of course).
Are there tuners in California who are familiar with these cars? Being rather a petrol head I know plenty of tuners who work on gas engines & management, but not on EV cars...

 

[dangerHV]

I cannot answer your question but I'd like to add to it since you brought up the speed limiter.
To start with, what happens if you hit 90 and keep the pedal to the metal? Does it act like cruise control and you stay at 90, up and down hills and all? If so I would like a "dial in" limiter control to take the place of the cruise control. With this, you could keep your foot on accel, not have to worry about the speed limit, (dial "5 over" when limit changes up or down) and letting your foot up will allow slowing as needed (ie: allowing a car to merge on the highway) without having to cancel the cruise control, then resume.
I've had several occasions where I came up on traffic too quickly by being "held" in cruise control mode. I don't use it often enough to instantly remember to tap the brake to coast down vs letting up on accelerator to coast down. The ability to dial in the max speed would give more control in my opinion.

David

 

[Nashco]

I'd like to take my lovely Spark EV for a spin around Sonoma Raceway, but that 90 MPH speed limiter is a royal pain in the butt!
Can it be removed / disabled / reset / overridden / defeated / obliterated ? (For off-road use only, of course).
Are there tuners in California who are familiar with these cars? Being rather a petrol head I know plenty of tuners who work on gas engines & management, but not on EV cars...

I haven't found anybody able and willing yet. If you figure out how, I'll gladly put my money where my mouth is. I'd shave seconds off my time at PIR if I could ditch the speed limiter...there are two long stretches where I only accelerate about half of the distance, the rest I have time to see the sights.

Bryce

 

[Zoomit]

Gosh, that motor must be spinning mighty fast at 90 mph. Just because we can't hear the mechanical stresses doesn't mean they aren't there!

 

[kevin]

I'd like to take my lovely Spark EV for a spin around Sonoma Raceway, but that 90 MPH speed limiter is a royal pain in the butt!
Can it be removed / disabled / reset / overridden / defeated / obliterated ? (For off-road use only, of course).
Are there tuners in California who are familiar with these cars? Being rather a petrol head I know plenty of tuners who work on gas engines & management, but not on EV cars...

I haven't found anybody able and willing yet. If you figure out how, I'll gladly put my money where my mouth is. I'd shave seconds off my time at PIR if I could ditch the speed limiter...there are two long stretches where I only accelerate about half of the distance, the rest I have time to see the sights.

Bryce

The speed limiter won't exist a separate item - it will almost certainly be integrated into the motor control software.

Even if you did patch the software to remove the limit, I don't think you would gain much. As you can see from the graph the torque is dropping off very rapidly at 90mph and this is dictated mainly by the motor design and battery voltage.

kevin

 

[pierred]

I haven't found anybody able and willing yet. If you figure out how, I'll gladly put my money where my mouth is. I'd shave seconds off my time at PIR if I could ditch the speed limiter...there are two long stretches where I only accelerate about half of the distance, the rest I have time to see the sights.

Bryce

I hear you. With the race cars, we typically figure the gear ratios by the longest straight, try to hit the rev limiter a bit before the brake point, then stagger all the other gears down from there. But here, uh, not even sure where to look. I would imagine it's just in the software or firmware and easy to modify. Has anyone reverse-engineered the code?

 

[pierred]

The speed limiter won't exist a separate item - it will almost certainly be integrated into the motor control software.

Agreed, that is most likely.

Even if you did patch the software to remove the limit, I don't think you would gain much. As you can see from the graph the torque is dropping off very rapidly at 90mph and this is dictated mainly by the motor design and battery voltage.

kevin

I've seen that plot before and it doesn't reflect the acceleration I experienced (perhaps it's for a different model?). Given that acceleration is proportional to axle torque, it should almost completely vanish according to the blue curve. Granted, I didn't have a proper data logger with me last time I tried, but the car was definitely still pulling like a freight train when all of a sudden it hit the speed limiter and something like "90MPH speed limit" showed up in red in the center console. The speed limiter felt like a soft rev limiter ("dah-dah-dah-dah-dah") but induced a stronger stutter in the car than a rev limiter would on a regular car. That was very surprising, in fact. My estimation is that we are leaving a good 20mph on the table, perhaps more.

 

[NORTON]

Another obvious thing to consider is, Electric Motors have Red Lines, just like Gas Engines have Red Lines.
Things start to break when you go beyond the stated red line.
If not immediately, then accelerated aging is happening and someday things will break.

Only the design engineers know for sure what the motor red line is.

I agree though, it does pull hard to 90 then just smoothly sits there. It 'Feels' like there is more, but who knows?

 

[Nashco]

There is still plenty of motor speed and power left on the table if you have a 2014, which has the lower gear ratio. The 2015+ went to a higher gear ratio, but the top speed limiter remains at the same 90 mph. Keep in mind that our motor spins very slowly compared to typical EVs, so I expect we'd get to power limitation (aero drag overcomes available motor power) before motor speed limits if we didn't have the speed limiter in place.

Bryce

 

[Zoomit]

There is still plenty of motor speed and power left on the table if you have a 2014, which has the lower gear ratio. The 2015+ went to a higher gear ratio, but the top speed limiter remains at the same 90 mph. Keep in mind that our motor spins very slowly compared to typical EVs, so I expect we'd get to power limitation (aero drag overcomes available motor power) before motor speed limits if we didn't have the speed limiter in place.

Bryce

Car and Driver tested the ICE 2014 Spark to a drag limited 103 mph. GM obviously has some rationale to limit the top end of the EV variant. If that rationale was not "motor speed limits", what components of the drive train, or vehicle dynamics, do you think caused them to limit the EV to 90mph?

 

[solder]

I haven't found anybody able and willing yet. If you figure out how, I'll gladly put my money where my mouth is. I'd shave seconds off my time at PIR if I could ditch the speed limiter...there are two long stretches where I only accelerate about half of the distance, the rest I have time to see the sights.

I think some speculation as to what module(s) actually implements the speed limiter might be more useful than money

 

[oregonsparky]

If the armature in an electric motor spins too fast the failure can be quite catastrophic. I saw it almost happen once in a power lab in college. The only thing that saved the lives of two undergraduate students was flames shooting out the front of a fluke ammeter that destructively acted as a big old fuse.

The prof was in the room and he heard the motor start to rapidly spin up when someone pulled the wrong power lead. He started yelling hit the breaker at the top of his lungs... I was at the next lab station which was a very large three phase motor generator pair.

When the armature is pushed past it's limits it will come apart and it suddenly stops spinning. It imparts all os it's momentum to the entire motor and rips the entire assembly off its mounts..

Jeff

 

[dangerHV]

GM obviously has some rationale to limit the top end of the EV variant. If that rationale was not "motor speed limits", what components of the drive train, or vehicle dynamics, do you think caused them to limit the EV to 90mph?

A couple of things come to mind. First, how many kw's is the motor drawing at 90 mph? Electric motor power ratings are based mainly on the ability to dissipate heat. If this motor is rated "100 kw", that is likely the peak "short term" rating. Long enough to accelerate to desired speed, up an incline, with full weight capacity, but not intended to remain at this load continuously. An IC engine CAN run at it's peak rating for long durations, so it's limitation is based on mechanical stresses (RPM's). (The water cooling jacket of an ICE is a very efficient system) I've seen some GE DC traction motors with a peak rating as much as 6 times its continuous rating. I don't know what the Spark's continuous rating is, but I sure would like to.
Another thing that may factor in is the permanent magnet motor design used. Magnets weaken with exposure to high temperatures. (how about a Leaf with a deteriorating battery AND motor capacity! That would really suck)
Also from what I've read on this forum, the stability of this 3,000 lb car isn't the best at highway speeds (at least not with stock tires). For those of us who aren't skilled high speed drivers, this could be quite dangerous.
Just a few possibilities...

David
ps, that poor Fluke...A few dollars spent on better balancing and bearings would eliminate that situation in the Spark. Some types of motors MUST have a load at all times cause they can spin up uncontrolled until exploding into shrapnel. Some fan motors and vacuum cleaner motors are like that. Quite scarry the 1st time it .... "teaches" you this lesson in motors.

 

[Dusty]

Why 90mph? It's an interesting question. If GM allows the gas Spark to go 103, it would seem plausible that the Spark EV, with its extra weight and lower center of gravity should be safe up to 120. I've hit the limit a couple times and the transition is abrupt indicating there is lots more umph left they aren't letting us use. According to my calculations, at 90 the motor is spinning less than 5500rpm. That's barely loping for such motors given the Tesla is allowed to spin over 16,000rpm.

Another possibility is the motor diameter. The coaxial drive shaft adds some extra girth, but we're only talking an inch or two. Shouldn't be a problem. And the tires are speed rated for 118; that's not it. Maybe it's just an experiment to see if drivers will be content with a car that only goes 90. After all, the Spark EV is the test run for the upcoming Bolt. Or maybe they set the top speed so low knowing some of us can't help ourselves and won't resist the temptation, and lose our driving privileges.

Personally I think GM set it low so it wouldn't top out faster than a gas Spark, a car they make money on. What to do about it, I haven't a clue.

 

[solder]

Another data point is -- the Volt apparently has a similar limit, but it's at 100mph.

 

[nikwax]

and GM changed the final drive ratio in 2015, so 2014 and 2015 are spinning at different speeds at 90 mph.

 

[CSW]

assumed due to some liability issues.....

 

[CSW]

There is still plenty of motor speed and power left on the table if you have a 2014, which has the lower gear ratio. The 2015+ went to a higher gear ratio, but the top speed limiter remains at the same 90 mph. Keep in mind that our motor spins very slowly compared to typical EVs, so I expect we'd get to power limitation (aero drag overcomes available motor power) before motor speed limits if we didn't have the speed limiter in place.

Bryce

I have a 2014 Spark. I think the 90mph limit is a bummer. It would be nice to at least do 100. I did not realize this about the 2014 vs. the 2015, as I actually have both the 14 and a 15. I have noticed my 14 gets significantly more range than the 15.... But I see the ratio on the 14 is 3.17..... I did not even know that EVs had ratios! But I do now.

 

[NORTON]

Why 90mph? It's an interesting question. .....(

And why limit it to 90 mph in Forward?

That's my question.
This motor and box O'gears is the same forward or reverse.

I want a SW hack to allow me to go 90 mph in Reverse !!!


Dang Nanny State,,,, Thanks Obama...

 

[Pegasus]

I want a SW hack to allow me to go 90 mph in Reverse !!!

You'll need to ask for the "stunt man special."