Chevy Spark EV Forum

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 Post subject: Re: 2015 Chevy Spark EV specifications
PostPosted: Sun Jun 26, 2016 1:05 pm 
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Joined: Fri Apr 29, 2016 4:21 pm
Posts: 30
Leafless wrote:
OK... Leafless here... new to this forum. Maybe a better handle would have been "Clueless." Well, maybe not 100% clueless, but certainly confused. Here is what I don't understand:

2014 Spark EV specs detail 400 ft. lbs. torque and use the 3.17 final drive ratio.
2015 Spark EV specs detail 327 ft. lbs. torque and use the 3.87 final drive ratio.

I understand that there is a difference in the batteries used for these two model years. And, since I have not been able to find any information relating to a change in the motor, I am assuming that the motors across these two model years are identical. (If I am wrong on this point, please enlighten me.)

So, why the difference in torque?

Also, I saw something indicating the the max rpm for the 14 is 5500 rpm. I haven't seen anything regarding the max rpm for the 15-16 Spark EV. Has this changed?

Note: This post was also added to the 400 ft lb topic... not sure which one is more appropriate.

I think the decrease in torque is to improve reliability, and along with the smaller battery capacity, an improve in efficiency.


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 Post subject: Re: 2015 Chevy Spark EV specifications
PostPosted: Sun Jun 26, 2016 2:28 pm 
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Joined: Mon May 25, 2015 12:19 pm
Posts: 499
Power output is the same, so reliability, etc. may not be true. Lower peak torque means less motor current at low RPM, but higher current at higher RPM, to a point.

Assuming 90 MPH (peak speed) = 133 ft/sec and tire radius is 1 ft (circumference = 6.28 ft), that will be 21 rev/sec, or 1260 RPM at tire. Gear ratio of 3.87 gives 4878 RPM, 3.17=4000 RPM. But the peak power at tire occurs at about 45 MPH, which is about 2400 RPM for 2015 an 2000 RPM for 2014.


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 Post subject: Re: 2015 Chevy Spark EV specifications
PostPosted: Sun Jun 26, 2016 10:20 pm 
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Joined: Sat Jun 18, 2016 8:33 am
Posts: 34
Location: SoCal
SparkevBlogspot wrote:
Power output is the same, so reliability, etc. may not be true. Lower peak torque means less motor current at low RPM, but higher current at higher RPM, to a point.

Assuming 90 MPH (peak speed) = 133 ft/sec and tire radius is 1 ft (circumference = 6.28 ft), that will be 21 rev/sec, or 1260 RPM at tire. Gear ratio of 3.87 gives 4878 RPM, 3.17=4000 RPM. But the peak power at tire occurs at about 45 MPH, which is about 2400 RPM for 2015 an 2000 RPM for 2014.


Your math may be a little bit off. The diameter of the 185-55-15 tire is 23", not 2 ft. According to my calculations, at 90 MPH, the 3.17 would be turning approximately 4200 rpm, and the 3.87 would be turning 5100 rpm. 45 MPH would be one-half the rpm. Assuming a maximum rpm of 5500 for the motor, the 3.17 would theoretically top out at 119 MPH; approximately 97 MPH for the 3.87.


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 Post subject: Re: 2015 Chevy Spark EV specifications
PostPosted: Thu Jun 30, 2016 3:13 pm 
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Joined: Mon May 25, 2015 12:19 pm
Posts: 499
Running some numbers, top speed will be about 95 MPH due to lack of power to overcome aerodynamics, regardless of the year. While looking at numbers, I ran some figures for acceleration and other stuff, too. Mathy folks might find the latest blog of some interest.

http://sparkev.blogspot.com/2016/06/spa ... lysis.html


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 Post subject: Re: 2015 Chevy Spark EV specifications
PostPosted: Fri Jul 01, 2016 5:40 am 
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Joined: Fri May 01, 2015 5:52 am
Posts: 1130
Location: KC,MO
SparkevBlogspot wrote:
Running some numbers, top speed will be about 95 MPH due to lack of power to overcome aerodynamics, regardless of the year. ...

We can't prove this because of the dang nanny SW, Thanks Obama... :roll: :mrgreen: (I know EV motors have red lines too..)
And I seriously doubt this is true.
The car has 130 HP. It is still pulling really strong when it suddenly hits 90 MPH then just stops the acceleration.
What's the top speed of the gasser Spark,, with it's much lower HP rating?

_________________
Used '14 2LT w/ DCFC.
+56k miles.


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 Post subject: Re: 2015 Chevy Spark EV specifications
PostPosted: Fri Jul 01, 2016 7:52 am 
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Joined: Mon May 25, 2015 12:19 pm
Posts: 499
Only way to prove definitively is to remove the SW limit and direct measurement. But if you go by torque curve and extrapolate, peak speed would be about 95 MPH. There are things in the universe that you don't need / can't make direct measurement to have pretty good idea about.

"Strong pull" is subjective. Math shows it'd be about 1/6 the pull of 35 MPH at almost 90 MPH. I describe this in the blog.

In a gas car, peak power is typically reached at high RPM, and 140 HP would be output close to max speed with gears. On SparkEV, that power is reached at 45 MPH. Read my blog post on how this was found and do the homework I ask if you really want to find the max speed with different gearing.


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 Post subject: Re: 2015 Chevy Spark EV specifications
PostPosted: Fri Jan 12, 2018 9:47 pm 
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Joined: Tue Oct 24, 2017 9:47 am
Posts: 31
emv wrote:
Also remember light colors stay cooler, giving better range since you can keep the AC off. Of course where you're from, I fear it's all moot. I don't see GM expanding sales past the west coast any time soon :( .

Buy black! Even if you live in Texas! The Spark EV A/C is pretty efficient, the heater not so much.

I have been getting my taste of 2.x miles per KwH lately while temps have been under 32º.

Thankfully I have DCFC and an EVgo card with 27 DFW area EVgo DCFC locations, so no problem. I can get where I need to go and keep warm.

That said, parking with the windshield facing the sun makes more difference than paint color. If the sun is actually out. But every little bit helps.


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 Post subject: Re: 2015 Chevy Spark EV specifications
PostPosted: Wed Feb 28, 2018 6:00 am 
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Joined: Thu May 07, 2015 2:31 pm
Posts: 28
NORTON wrote:
SparkevBlogspot wrote:
Running some numbers, top speed will be about 95 MPH due to lack of power to overcome aerodynamics, regardless of the year. ...

We can't prove this because of the dang nanny SW, Thanks Obama... :roll: :mrgreen: (I know EV motors have red lines too..)
And I seriously doubt this is true.
The car has 130 HP. It is still pulling really strong when it suddenly hits 90 MPH then just stops the acceleration.
What's the top speed of the gasser Spark,, with it's much lower HP rating?


I think it might be fairly easy to see how much power it takes for the Spark EV to run at 90 mph; go to a straight stretch of road and run her up to 90, and watch the power meter and see what it's reading (on my cluster I keep the range meter on the left and the power meter configured to the right). 120kw is max power output; I'd be curious to see what the power output was at a steady state 90 mph. I'd bet that it will be less than 60kw. of course increasing the speed vs power output isn't linear, but it would give a baseline to see how efficient the aero and frontal area of this car are (again I'm betting they are quite good).

as an FYI -- I drive a EVSR pure electric sports racer road race car (one of three built by Entropy Racing) at various venues. it is direct drive RWD driving the rear wheels by means of a standard type LSD differential. the motor is 160 hp with about 250 lb-ft tq. we use a 25 kwhr pack. the car weighs 2100 without driver. aero on it is not particularly good; it's an old design body (same almost identically to a Spec Racer Ford, except we have removed all radiator openings and smoothed out the rear end some) and the cockpit is open with lots of buffeting and wind resistance. we have different gear ratios that we run on the car (wheels are 15" and we run 205-50-15 Toyo RA1 tires on it) -- the most commonly run gear ratio for most road race tracks we run is the 4.44 ratio. this gives a working top speed of about 120 mph which is good for most tracks. the 'redline' of our motor is 8k rpm. for shorter tracks we run a 4.75 rear gear, and for hill climbs we run a 5.50 or even a 6.50. acceleration is enhanced coming out of the corners but top speed drops (of course) also. the 'sweet spot' of our EVSR racecar seems to be around 4-6k rpm; they feel very strong pulling there. they happily spin to 8k rpm with no complaints but you can definitely feel them 'dropping off' above 7k rpm. the engineers told me that this is the 'field weakening' effect of the electric motors we use. one time just for fun we went to Pocono Raceway and ran the entire Tri-Oval; we put a very tall gear in the car (I think it was a 3.15) and we hit a radar indicated top speed of 141 mph (drag limited; we were no where near the 8k rpm redline).

anyway, my seat of the pants feel is that if the speed limiter was removed from a 2015 Spark EV, that it would do a little better than 90 mph but would then hit the redline rev limit of the motor. but a 2014 with the taller gear would almost certainly break 100 pretty easily.

attempt at posting a pic of me and EVSR:
https://1drv.ms/u/s!AmUHWCpbUJmAqgMQljvi2D21yeg9


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 Post subject: Re: 2015 Chevy Spark EV specifications
PostPosted: Sun Mar 11, 2018 10:42 am 
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Joined: Sun Nov 15, 2015 10:16 am
Posts: 23
Location: Saline, Michigan
As for top speed, my 14 hits 90 so easy it's got to be able to run over 100 without speed limiting but in my opinion not the best idea with the eco tires which is probably why they limited it. I'm sure there are the ones on here who are thinking why would you want to go that fast? It's not an everyday thing, just every once in awhile but the 90mph top really doesn't bother me. I would imagine the 15+ models with the better gearing and programming would really be a lot of fun driving.


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 Post subject: Re: 2015 Chevy Spark EV specifications
PostPosted: Tue Sep 25, 2018 7:57 pm 
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Joined: Mon Sep 03, 2018 10:34 pm
Posts: 10
I drive a '15 and it's very efficient on city streets. However as soon as I get on the highway at 60-70 mph the trend line on the guessometer drops like a stone. On city streets I can do a 10-mile drive at over 7 mi/kwh while on the highway it's below 5. I think the '14s may have a better blend of city/highway efficiency. It kind of makes me avoid highways which is sad. Still a great car though! No regrets in buying it off a lease return, except for some BO left by the previous owner that I can't get out of the vinyl seats yet.


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