PERFORMANCE TUNING ANYONE?

[WetEV]

You're right it's a AC motor. Those actually do provide 100% torque at full speed. They deliver 100%+ from break torque and pull up torque, which makes the "100% torque" true. Which is better than 300% torque off the line.

Reason I got all wrapped up in DC is the EMW and a few others conversion kits I've been looking at use DC/DC. Makes me wonder just how much AC voltage is coming out of this battery. I thought I saw the battery at 480 volts or so.

The diagram you give is for a fixed frequency induction AC motor. The inverter puts out a variable frequency, so is rather different. There are two areas of interest: Torque limited, when the inverter is outputting the maximum design current, and power limited. This diagram is for a Tesla Roadster, but should be fairly similar in shape (but the peak torque and power are different, of course: 92 kW (125 PS; 123 bhp) and 181 lb·ft (245 N·m) of torque.[):

http://2.bp.blogspot.com/-l-P9WrMQxaY/T4yW465IDLI/AAAAAAAAByU/5mVHR-n-8CQ/s1600/Torque+Curve.png

 

[jumpjack]

It is an electric motor--there is no torque curve.

Actually yes there is a torque curve. There has to be or "power" could not increase.

If this motor only had 1 RPM what you're saying would be true. But it's a variable speed, thus variable torque motor. Otherwise all speed and power would be handled through a CVT transmission and not a single gear transmission. It is what I would refer to as torque crap out. It's there, right off the line, all of it, but it is not a all off the torque all of the time as commonly referred to.

Here it is an example of real torque/speed curve (for Renault Zoe):

Another (For Renalut Fluence):

Tesla S:

 

[Anonymous]

I know there is a big bulky thing in the trunk that takes up a bunch of space...maybe take that out.
Not sure the organizer is going to make much of a difference...but I have thought how much better if the FFE could be if it were 18" shorter as a 2 seater coupe and some of the battery weight over the front tires.

My 2014 Smart Fortwo Electric Drive is a 2 seat coupe.
Dattery located central and low in the vehicle as per:

The handling is rather more harsh than my old 200x Ford Focus (which had brilliant handling for a cheap ICE commuter car) but still very good, especially in tight city streets, where having the heavy battery low in the car helps with early turn-in.

The official spec's say 0-100KPH in 11 seconds, but mine gets there in 9ish, so not sure why Smart publishes a slow time...and the 0-60KPH is just a hair over 4 seconds, which is plenty quick for the short range driving I do.

We'd all love a Telsa roadster, but for me, this little 2 seater is like driving the future today. Love it!

 

[EVA]

My brain is not doing very well with the charts JumpJack posted - I can't quite wrap my mind around what they mean in real world terms. Usually I'm good at that kind of thing - these escape me for some reason.

Anyway - the Tesla abbreviations are:
M S60 is the Model S 60KW battery - standard motor (call it the base Tesla)
M S85 is the Model S 85KW battery with a slightly stronger motor (the midrange Tesla)
M SP is the Model S Performance - that car has the same 85KW battery, and a much stronger motor.
There is one more model they left off (the chart might be old, so that car wasn't available then) the Model S Performance Plus.

MS 60 0-60 is 5.9 seconds (302 hp)
MS 85 0-60 is 5.4 seconds (362 hp)
MS P85 0-60 is 4.2 seconds (416 hp)

 

[jumpjack]

My brain is not doing very well with the charts JumpJack posted - I can't quite wrap my mind around what they mean in real world terms. Usually I'm good at that kind of thing - these escape me for some reason.

They mean that torque in EVs is not actually "constant at any RPM", but "constant up to xx RPM", unlike ICEVs, where it is never constant but it has a peak at specific RPM.
This translates in constant acceleration (Torque --> Force --> acceleration) from 0 to xx MPH, then acceleration decreasing as 1/v from xx MPH to maximum speed.
Torque results in having an upper RPM limit because it's tied to power by P=F*v relation, so to have a constant F=P/v while v increases, Power must increase too (P=K*v)... but of course it can't increase for ever: once P reaches its maximum value (i.e. maximum allowed current in motor windings), it becomes constant, hence F=P/v =K*v/v becomes instead F=Pmax/v and it starts going as 1/v.
If you look at torque/speed chart for ICEVs at different gears, you'll see that the overall curve obtained with 5 gears is slightly equal to the single curve of an EV.

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Talking about tuning.... is it possible to use OBD bluetooth devices and a smartphone also to EDIT electric car parameters besides just reading them? i.e. maximum current, minimum allowed battery SOC, and so on... But maybe this would be better named as hacking rather than tuning! ;-)

 

[jumpjack]

But beware of this:

This is NOT how actually EV/ICEV torque/speed curves compare!

here it is the "reality":

Tractive effort comparison between ICEv and EV (torque/speed curve)

Torque/speed curve for Automatic transmission

I also found this, but I can currently explain only first two regions of the curve, I'm still figuring out the reason of the "natural characteristic region" on the right...

 

[epaminondas]

Unless its my imagination, It is faster off of the line in L and you can generate wheel sin. It doesn't have the soft start that it does in D

 

[davideos]

I personally haven't noticed, but when I get my car back with a new battery, I'll put it to a stopwatch and find out. Should be a relatively easy experiment to conduct.

 

[WattsUp]

Unless its my imagination, It is faster off of the line in L and you can generate wheel sin. It doesn't have the soft start that it does in D

You can chirp the tires in D too. You just have to be turning the steering a little bit.

I think you're imagining any difference in acceleration between D and L. L is all about regeneration, not acceleration.

 

[hcsharp]

Unless its my imagination, It is faster off of the line in L and you can generate wheel sin. It doesn't have the soft start that it does in D

It's your imagination. The owners' manual says the only difference is regen braking is stronger in L.

 

[Tom French]

In "L", I can spin tires easlier then in "D".

I run normal 38psi.

"L" also gives me a longer range, seems to charge the battery with stronger amperage.

 

[bb6lude]

I light the tires in the wet every time. Can't wait until the tires wear out and I can replace them with something stickier.

My guess is that the extremely hard tires cause the traction control to back way off. I wonder if it would be a bit more zippy with more sticky tires.

 

[Don Eyermann]

I bought my Ford Focus in January...and I love it. And while it may not be a "Sports Car", let me say I have had a number of sports cars....I am 70, my first "Sports Car" was a 1956 Porsche "365A" with 1500S engine....yes the original VW 2 piece block modified to be a Porsche engine. Then I had a MG Midget, onto which I later attached a Bug Eye Sprite front end, then a Triumph TR-7 and a Karman Ghia, then I had a 1975 Toyota Supra, and presently I have an early 1950's MGTD fiberglass replica on a VW chassis.... With the exception of the Porsche (I think) and of course the Supra the Ford Focus Electric out accelerates and out corners the rest of the true "Sports Cars" in my list. It will also out accelerate and out corner many of the "family sedans" I have owned...but not my "Muscle Cars". I also had a British MINI Minor, that was modified with a 1275 engine onto the original 850cc engine transmission (if there are any MINI enthusiasts out there, you know the 850 tranny will not allow the 1275 crankshaft to make a full revolution...so being as I was "poor" but determined engineering student, I cut rectangular holes in the block to allow the crank to rotate. Then I fashioned a "Cover" pan that fit over the 4 cutouts and with the last of several sealing attempts being a cut up inner tube...it did not leak!!) With the 1275 engine on the lower geared 850 transmission...and being as it was a MINI...the Ford Focus is neither as fast nor would out corner it...but I digress (hope you got a chuckle out of the story). And get that I have a viable history of Sports Car ownership and driving experience....
So, I would indeed LOVE to have a bit of tweaking to my Ford Focus EV to make it go faster off the line...including wheelspin...Sometimes I like wheelspin. Sure I know it loses traction and is slower...so what, its FUN! Good old fashioned FUN. I used to take my Corvair Corsa with the 4 carbs and 140 hp and yank on the hand brake and spin it "BAT-TURN" style. I lived in Missouri...it snows a lot there in winter...I drove "Wild & Crazy" on parking lots in the snow...as well as in fallow corn fields....and on back roads in rural Missouri. I learned to control my vehicle in the snow and ice ...Thus I don't get stuck and have never had an accident in the winter. Plus I have avoided hitting other "less experienced" drivers who did lose control. So, if anybody out there has knowledge of "hackers" who have played with the controller codes....give me an opportunity to play [email protected]

 

[jmueller065]

If you want wheel spin: Use the left menu on the dash to go into the vehicle settings and turn off the traction control (sadly this will only "stick" until you turn off the car, then it will default back to "on").

Another hint for speedier takeoffs is to goose the accelerator just a little to get it rolling before flooring it: The Ford cal restricts full-throttle acceleration but backs off a bit if the car is already rolling.

 

[Texas FFE]

No, no, no! None of these posts are useful or knowledgeable! Why are the knowledgeable people on this forum keeping quiet on this subject?

The Nissan Leaf has a lot less power than the FFE but is just as fast 0 to 60 mph. The Leaf and the FFE have about the same amount of torque but I've heard that the Leaf pulls much harder off the line. The FFE definitely has a torque limiter at low speeds.

I'm not terribly interested in making my FFE faster but I would like to see it live up to it's potential. I don't like the idea of getting beat by the much less powerful Nissan Leaf, even if it's just for a few feet. I would think that someone would have figured the torque limiter out and figured out a way to override or modify it.

 

[rsanders4]

Exactly. The FFE is pretty nerfed off the line. I would *LOVE* to get into the guts of the FFE's ECU with Forscan or the like.

Here's an interesting tidbit. The FFE's "torque limiter" isn't active in reverse.
That's just stupid. You'd think the smart thing to do would be to nerf the throttle response in reverse.

As I've said in numerous threads, I've noticed Ford's tendency to be more "conservative" with everything on the FFE.


Nerfed throttle response. Only using 18 Kwh of a 24 Kwh pack, etc, etc.
My understanding is the 100+mi range in the 2017 was just an ECU change, and not a new battery pack.

 

[Jamez]

Well, the Leaf has 300lbs less weight than the FFE, so perhaps start by adding some lightness...

 

[EMP40]

The Leaf is just that in side impact crash. Once I watched the video the Leaf was not an option.

 

[WattsUp]

Here's an interesting tidbit. The FFE's "torque limiter" isn't active in reverse.

Probably full torque forward would always spin the wheels, but full torque in reverse does not -- due to increased down-force on the front wheels as the car accelerates backwards.

Still, odd that full torque in reverse is apparently allowed. If anything, you would think the torque might be even MORE limited in reverse -- to make it more difficult to make a mistake when driving backwards.

 

[toddh]

The limited Torque on takeoff seem to me to be a programming of the inverter power curve.

As another stated Ford has been very conservative with this car which is understandable given it's their first mass-produced EV.

Tapping the pedal from standstill in a Leaf and the Focus is a different feel. The Focus almost feels like you're on a rubber band whereas the torque on the Leaf is more substantial and instantaneous. I have a feeling if you lined up a Focus and a Leaf, the leaf would beat it off the line but the Focus would catch up rapidly.

A very simple example is the Toyota RAV4 or Tesla which have performance modes. I have a Toyota RAV4 and when you put it in performance mode a slight depression of the petal gives you a much more aggressive response and surge of power.

I think that Ford simply programmed a very conservative power curve from the line possibly to prevent wheelspin but also to protect their electrical components from standing start power surges.



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