WetEV
Posts: 27
Joined: Thu May 03, 2012 7:04 am
Location: Near Seattle

Re: PERFORMANCE TUNING ANYONE?

Thu Nov 14, 2013 4:06 pm

az erik wrote: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/T ... +Curve.png

jumpjack
Posts: 3
Joined: Thu Apr 17, 2014 12:25 am

Re: PERFORMANCE TUNING ANYONE?

Thu Apr 17, 2014 1:24 am

az erik wrote:
jmueller065 wrote: 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.
Image

Image
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.

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

Another (For Renalut Fluence):
Image

Tesla S:
Image

SmartElectric

Re: PERFORMANCE TUNING ANYONE?

Thu Apr 17, 2014 8:15 pm

davideos wrote: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:

Image

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
Posts: 874
Joined: Tue Aug 06, 2013 9:10 pm
Location: Chicago Area

Re: PERFORMANCE TUNING ANYONE?

Thu Apr 17, 2014 10:26 pm

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)
2014 Platinum White FFE (Turning in mid Dec. 2016 25,000 miles)
2013 Ingot Silver FFE
2012 Titanium ICE Focus
2014 Tesla Model S 85

jumpjack
Posts: 3
Joined: Thu Apr 17, 2014 12:25 am

Re: PERFORMANCE TUNING ANYONE?

Fri Apr 18, 2014 12:12 am

EVA wrote: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.

-----------

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
Posts: 3
Joined: Thu Apr 17, 2014 12:25 am

Re: PERFORMANCE TUNING ANYONE?

Fri Apr 18, 2014 12:26 am

But beware of this:

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

here it is the "reality":
Image
Tractive effort comparison between ICEv and EV (torque/speed curve)

Image
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...
Image

epaminondas
Posts: 58
Joined: Tue Sep 02, 2014 10:46 am

Re: PERFORMANCE TUNING ANYONE?

Thu Sep 04, 2014 1:34 pm

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
2014 Ford Focus Electric -silver
2005 MBZ 350 ML
2008 Scion TC
1996 Ford F250 Powerstroke
(runs bio diesel)

davideos
Posts: 409
Joined: Mon Jan 21, 2013 8:58 pm
Location: So Cal

Re: PERFORMANCE TUNING ANYONE?

Thu Sep 04, 2014 5:42 pm

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
Posts: 2113
Joined: Mon Jan 07, 2013 2:58 am
Location: SF Bay Area, CA

Re: PERFORMANCE TUNING ANYONE?

Thu Sep 04, 2014 7:14 pm

epaminondas wrote: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.
2013 FFE, Platinum White, Delivered January 2013
2017 MS, Midnight Silver Metallic, Delivered February 2017
Use my referral code (http://ts.la/matt4377) to save $1000 on your next Tesla AND get free unlimited Supercharging!

hcsharp
Posts: 108
Joined: Mon Aug 05, 2013 1:40 pm
Location: Vermont

Re: PERFORMANCE TUNING ANYONE?

Thu Sep 04, 2014 8:21 pm

epaminondas wrote: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.

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