Coulomb
Moderator
- Joined
- Apr 24, 2021
- Messages
- 2,273
- Solutions
- 1
- Reaction score
- 1,829
- Points
- 645
- Location
- Brisbane, Australia
- Driving
- MG4 Trophy ER
My understanding is that the motor and motor controller are identical between the two models, but because the SR model has a higher voltage battery, my guess is that field weakening happens at a higher speed. The difference in peak power isn't massive, it's 13% (130 kW versus 115 kW).from what I read the SR has a more powerful motor, significantly so. Is it higher geared so that the motor will wear better?
So up to the field weakening point for the LR model (usually very roughly 40 mph), the two models would perform identically. Then for the next 5 mph or so, the LR model will be limiting its field excitation and hence torque (to keep the back-emf less than the battery voltage), while the SR model will still be running at full torque. By the speed that the SR model has to limit torque, it will be moving at about 13% more speed. Speed times torque equals power, hence the peak power of the SR model is 13% higher than that of the LR model. Both models will have roughly constant power beyond their field weakening points.
The reason for the difference in battery voltage is merely an accident of the cell chemistry and the way the cells pack into the battery space available.
So this won't affect the speed of the motor, including top speed (which is probably software limited anyway). So I believe that the motor bearing life will not be different between these two models.
[ Edit: added toque curve. ]
[ Edit: moved to new ZS EV topic for easier finding ]
Last edited: