EV total range variation based on motor size

5022 Views 8 Replies 6 Participants Last post by Cypressor, Jun 18, 2018

kingzilla

Discussion Starter · Dec 29, 2016

A friend of mine had an E-trike that worked on a 1 KW motor and had a curb weight of 350KG and had a range of rougly 40 miles using 48V/100Ah Lead acid batteries at 20-25 mph.

Is it safe to assume if I have a similar build but replace the 1 KW motor with a 5 KW motor that I should still get more or less the same performance (except maybe speed?)

Any replies will be appreciated.

Thank You

Save

1 - 9 of 9 Posts

dougingraham

· #2 · Jan 5, 2017

I wouldn't make that assumption. Generally speaking it is easier to make a larger motor more efficient than a smaller motor. But if you operate the motor outside of its efficiency band then this might not be true. A larger motor is going to be heavier and this will make acceleration and deceleration slightly less efficient.

You will probably need a different final drive ratio to get the most out of these motors. Just replacing the one motor with the other probably won't be optimal.

Save

GoElectric

· #3 · Jan 9, 2017

I would agree with what Doug said, but he is being very precise. I would say in general, that you will do about the same, but with much better acceleration and top speed!

My two cents.

Save

MathisLaurant

· #4 · Feb 24, 2017

If you were to run the motor at the same speeds then maybe deepening on the RPM you are running at and the efficiency the motor makes at that RPM. You may get the same range or close, but like said above, you will be heavier and things change. I'd check the spec of both motors and see what their efficiency are at a specific RPMs, and you may have to play with your vehicles gearing to operate in the motors Max Eff. And from there extrapolate.

Save

Cypressor

· #5 · Jun 17, 2018

So, if under the same throttle %, is it safe to say that the miles achieved by a 100hp moto would be the same as a 200 hp, if the 100 hp is not working out of it's normal working range?

Sent from my SM-N950U using Tapatalk

Save

Emyr

· #6 · Jun 17, 2018

Cypressor said:
So, if under the same throttle %, is it safe to say that the miles achieved by a 100hp moto would be the same as a 200 hp, if the 100 hp is not working out of it's normal working range?

The comparison isn't about throttle %.

For the same vehicle speeds, hence same motor output (assuming the smaller motor has ballast to bring it to the same weight as the larger to make the comparison easier), different motors will have different efficiencies according to their design and construction.

Save

dougingraham

· #7 · Jun 17, 2018

Cypressor said:
So, if under the same throttle %, is it safe to say that the miles achieved by a 100hp moto would be the same as a 200 hp, if the 100 hp is not working out of it's normal working range?

Sent from my SM-N950U using Tapatalk

It is about efficiency, not % of throttle. Mechanical power out / electrical power in. If the two motors are approximately the same efficiency at the comparison power level then the range would be close, probably even difficult see the difference. There are however other considerations and the added weight of the heavier motor will slightly lower the overall efficiency. The heavier motor could want lower voltage and higher current in order to obtain the same power level. This could require heavier cables. There will almost certainly be a change in drive ratio. You can think of the differential as consuming ~5% of the motor power and a transmission about 10%. If your new motor allowed you to get rid of the transmission that would be a pretty big win on overall drive train efficiency including the space reclaimed by the transmission and the weight of said component.

Save

Cypressor

· #8 · Jun 18, 2018

dougingraham said:
It is about efficiency, not % of throttle. Mechanical power out / electrical power in. If the two motors are approximately the same efficiency at the comparison power level then the range would be close, probably even difficult see the difference. There are however other considerations and the added weight of the heavier motor will slightly lower the overall efficiency. The heavier motor could want lower voltage and higher current in order to obtain the same power level. This could require heavier cables. There will almost certainly be a change in drive ratio. You can think of the differential as consuming ~5% of the motor power and a transmission about 10%. If your new motor allowed you to get rid of the transmission that would be a pretty big win on overall drive train efficiency including the space reclaimed by the transmission and the weight of said component.

Thanks!

Been looking at converting an old 60s/70s beetle.

Sent from my SM-N950U using Tapatalk

Save

Cypressor

· #9 · Jun 18, 2018

Emyr said:
The comparison isn't about throttle %.

For the same vehicle speeds, hence same motor output (assuming the smaller motor has ballast to bring it to the same weight as the larger to make the comparison easier), different motors will have different efficiencies according to their design and construction.

Where can I start researching about that particular topic, more efficient engine design etc for the electric side?

Sent from my SM-N950U using Tapatalk

Save

1 - 9 of 9 Posts

This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.

Top Contributors this Month