2014 Chevy Spark 100Kw Permanent Magnet Motor

[ridethelightning]

thanks hh, but not quite direct drive.
driving the tailshaft to the diff which is 3.5/1 ratio I believe.
I am also going to be using lower voltage, `~150v, possibly 300v if i reconfig the cells, so this may also make it less efficient with lower rpm??
I could also keep the spark stock gear assembly.

 

[okashira]

thanks hh, but not quite direct drive.
driving the tailshaft to the diff which is 3.5/1 ratio I believe.
I am also going to be using lower voltage, `~150v, possibly 300v if i reconfig the cells, so this may also make it less efficient with lower rpm??
I could also keep the spark stock gear assembly.

I don't think you can use the stock transmission. It's meant for FWD.

It is however an inline transmission, and the rotor shaft has a spline. you could remove the transmission gearset, the differential, and use the existing output of the transmission case for your custom shaft (with female to male spline) to go to a custom driveshaft. You might need another bearing support near the seal.
(and plug the other hole where the opposite axle came out)

I am 99.9% sure this is never done before but the power/torque/gearing works okay with a toyota pickup with a 3.5 rear end ratio. Actually, I think the 2014 spark is like 3.6 to 1 so it's pretty darn close.

Lower voltage would limit top speed before any field weakening needs to happen on the controller. before that efficiency is not affected but if you need to drive with field weakening much of the time efficiency would be affected.
Let me find the report I have from chevy that shows motor performance

The spark motor is bar wound stator based on a REMY design so the DC resistance is really low. Can take lots of amps.

 

[okashira]

Here is the spark motor efficiency chart:

Note the drop off in torque between 0.45 and 0.85 RPM.
I think this is where things are voltage limited and anything beyond that requires field weakening.
It is hard to tell from the report. But I think 1.0 refers to 4,500 RPM on the x axis. And 1.0 on the y-axis refers to 500n-m torque. And the test was done at 350V DC.
IF you were using, say 175V, then the drop in torque would happen at slightly more then half the torque on the chart.
Efficiency in regions before the drop would not be affected. but outside efficiency would be lower ( I could try to draw something to estimate)
Lots of speculation here without actually testing the motor.
Send me an email if you want the spark motor design report.

Here is the spark motor cross section: ( I added the labels in red)

You would want to remove
1.) Both Output shafts
2.) Differential
3.) Planetary Gear-set
4.) Add a new shaft that will fit into the Rotor Shaft and goes out the existent seal to the right connecting to your drive shaft.
5.) Plug the hole on the left side

 

[ridethelightning]

thanks for the info.
I had a chat to a local Australian ev company guy, Tim ,from ev works, regarding using the spark motor.
he suggested using close to the stock battery voltage as possible, for best results.

Im thinking the best plan would be to split the tesla packs to double the number in series, that way there would be 7(modules)x 12(cells) x 3.6v = 302v nominal, 344v charged if to 4.1v/cell , which is ball park.

I wish i could make it 8 modules

He seemed to think getting the splines machined to fit the rotor would be possible providing you had the correct design.

 

[sam110]

i think the motor in the back of the lexus 400h hybrid 4 wheel drive is the best choice for a motor. they may be more common in the junkyards too.

Any lead to the detail on how to repurpose this Lexus rear motor? I would love to learn about this.

Thanks
Sam

 

[Arlo1]

thanks for the info.
I had a chat to a local Australian ev company guy, Tim ,from ev works, regarding using the spark motor.
he suggested using close to the stock battery voltage as possible, for best results.

Im thinking the best plan would be to split the tesla packs to double the number in series, that way there would be 7(modules)x 12(cells) x 3.6v = 302v nominal, 344v charged if to 4.1v/cell , which is ball park.

I wish i could make it 8 modules

He seemed to think getting the splines machined to fit the rotor would be possible providing you had the correct design.

Yes you don't want lower than OEM voltage if anything a little higher will help. Many of these motors use a decent amount of field-weakening as it is and the point where the FW starts is where you torque starts to slowly taper off. If you use a lower voltage that rpm is lower as well meaning you won't get the same top speed but also will be in FW earlier. Most EVs are usually not in FW at cruise speeds on the highway but will go into FW as you accelerate past that speed. This keeps them as efficient as they can be and gives great torque at those speeds.