General Category > Electric/Hybrid Car Conversion
8 Seater Buggy Conversion
Bikemad:
Hi Nik,
I seem to recall an axle was also available from GM with a much lower 12.5:1 gear reduction, if this is still available, it would produce almost 65% more torque at the axle from your existing motor, but I still feel it would be underpowered.
According to the GM website, the 20kW motor has a rated torque output of 80Nm with a peak torque of 160Nm:
Model: HPM-20KW -- High Power BLDC Motor
Voltage:72V/96V/120V
1. Voltages: 72V-120Vdc
2. Rated power: 20-25KW
3. Peak power: 50KW
4. Speed: 3200-6000rpm
5. Rated torque: 80 Nm
6. Peak torque: 160 Nm
7. Efficiency: >90%
8. Dimensions: 30x30x25cm
9. Weight: 39kgs
10: Cooling: liquid cooling
If my calculations are correct, your vehicle should just about be able to climb a 7.8° slope (13.4%) with 80Nm of torque, and with the maximum peak torque of 160Nm it should even be able to climb a 17° slope (30.6%).
I have assumed your differential incorporates the 7.6:1 gear reduction as indicated on the current drawing.
I used a tyre diameter of 600mm in my calculations, so the slope angles will be slightly higher if your wheels are smaller (or less if your wheels are bigger).
Unfortunately, the performance data figures for the dynamometer test are not shown below 2560 rpm, so I don't know how many Amps will be required to achieve the peak 160Nm of torque at very low rpm.
Alan
Enemzack:
--- Quote from: Bikemad on February 16, 2017, 08:43:17 PM ---Hi Nik,
I seem to recall an axle was also available from GM with a much lower 12.5:1 gear reduction, if this is still available, it would produce almost 65% more torque at the axle from your existing motor, but I still feel it would be underpowered.
According to the GM website, the 20kW motor has a rated torque output of 80Nm with a peak torque of 160Nm:
Model: HPM-20KW -- High Power BLDC Motor
Voltage:72V/96V/120V
1. Voltages: 72V-120Vdc
2. Rated power: 20-25KW
3. Peak power: 50KW
4. Speed: 3200-6000rpm
5. Rated torque: 80 Nm
6. Peak torque: 160 Nm
7. Efficiency: >90%
8. Dimensions: 30x30x25cm
9. Weight: 39kgs
10: Cooling: liquid cooling
If my calculations are correct, your vehicle should just about be able to climb a 7.8° slope (13.4%) with 80Nm of torque, and with the maximum peak torque of 160Nm it should even be able to climb a 17° slope (30.6%).
I have assumed your differential incorporates the 7.6:1 gear reduction as indicated on the current drawing.
I used a tyre diameter of 600mm in my calculations, so the slope angles will be slightly higher if your wheels are smaller (or less if your wheels are bigger).
Unfortunately, the performance data figures for the dynamometer test are not shown below 2560 rpm, so I don't know how many Amps will be required to achieve the peak 160Nm of torque at very low rpm.
Alan
--- End quote ---
Hi Alan,
we managed to disassemble the differential gear and attached is the number of teeth in the gear. now is in the process to design and fabricate the bracket for the massive motor :o
any advise? might need to add few gear for the motor
Bikemad:
Hi Nik,
According to the tooth count, your final drive has a total gear reduction of 10.27245:1 which is good for hill climbing but not so good for top speed. ::)
The stated 160Nm of peak motor torque should produce ~1643Nm of torque at the wheel, which would provide a forward force of around 5370N (547kg) with 600mm diameter tyres. That's enough force to climb a slope of over 23° (43%). :o
The top speed will be limited by the motor maximum rpm (which is probably going to be ~4800rpm @ 96V) and at 4800rpm it would only achieve a maximum of 32.85mph (52.87km/h) with 600mm diameter tyres.
Alan
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