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ProDigit · 11-20-2020, 12:25 AM

So, I've been thinking about adding a small LiPo battery in my trunk, and add one or two motors to the rear wheels.

DC Brushless motors would be easiest, but are (due to their low wattage ratings) out of the question.
Two of those electric bicycle hubs of 1500W can actually propel a car to about 25-30MPH, but can usually not surpass more than 45-50MPH before the motor craps out. Meaning highway driving (even on gasoline only), is not good for them.

So AC motors is the next best thing.

Most AC motors sold online, run up to about 4k RPM.
Most car wheels rotate up to about 1500RPM (at about 105-110MPH).
That means if the motor can be paired directly to a 3:1 reduction gear (be it either sprockets and a chain, or better yet, a mini gearbox), their rated torque figures could triple. Making it possible for them to actually be useful.

I've looked around, and the cheapest variable speed AC motor options available, are those from a washing machine; and not much worse compared to an industrial motor.
China actually sells these $2-3k 4 person mini vans with 1 of these motors, allowing the van to accelerate to 30MPH just fine.

I'm not trying to make a tesla here...

These motors have a peak HP rating of about 5HP, and I can presume (from the performance seen) to have about 5LB FT of Torque.
With the 3:1 reduction gear, that results in 10-15 LB FT of torque added.
Use 2 of them (one for the left rear, one for the right rear wheel), and that's around 20LB FT of torque (there are losses with reduction gears, and the motor running at higher RPM).

With the battery, motors, contraption, wiring, etc.. It's not going to make my car faster, nor accelerate better.

It will only offer:
1- All Electric Drive (mainly in low speed environments)
2- A better MPG and gasoline range by using electric and gasoline simultaneously, instead of driving on gasoline only.

Adding two of these motors to my car (with 20HP max rated), would mean I could drive all electric up to about 55MPH.
Anything beyond that, would most likely just take some of the MPG edge off (instead of 25-29MPG on the highway, I could be running 29-33MPG).

Anyone has ever tried something like this?

11-20-2020, 12:25 AM	#1 (permalink)
ProDigit EcoModding Apprentice Join Date: Jun 2012 Location: Florida Posts: 222 Thanks: 0 Thanked 22 Times in 18 Posts	Add electric motor to extend range? So, I've been thinking about adding a small LiPo battery in my trunk, and add one or two motors to the rear wheels. DC Brushless motors would be easiest, but are (due to their low wattage ratings) out of the question. Two of those electric bicycle hubs of 1500W can actually propel a car to about 25-30MPH, but can usually not surpass more than 45-50MPH before the motor craps out. Meaning highway driving (even on gasoline only), is not good for them. So AC motors is the next best thing. Most AC motors sold online, run up to about 4k RPM. Most car wheels rotate up to about 1500RPM (at about 105-110MPH). That means if the motor can be paired directly to a 3:1 reduction gear (be it either sprockets and a chain, or better yet, a mini gearbox), their rated torque figures could triple. Making it possible for them to actually be useful. I've looked around, and the cheapest variable speed AC motor options available, are those from a washing machine; and not much worse compared to an industrial motor. China actually sells these $2-3k 4 person mini vans with 1 of these motors, allowing the van to accelerate to 30MPH just fine. I'm not trying to make a tesla here... These motors have a peak HP rating of about 5HP, and I can presume (from the performance seen) to have about 5LB FT of Torque. With the 3:1 reduction gear, that results in 10-15 LB FT of torque added. Use 2 of them (one for the left rear, one for the right rear wheel), and that's around 20LB FT of torque (there are losses with reduction gears, and the motor running at higher RPM). With the battery, motors, contraption, wiring, etc.. It's not going to make my car faster, nor accelerate better. It will only offer: 1- All Electric Drive (mainly in low speed environments) 2- A better MPG and gasoline range by using electric and gasoline simultaneously, instead of driving on gasoline only. Adding two of these motors to my car (with 20HP max rated), would mean I could drive all electric up to about 55MPH. Anything beyond that, would most likely just take some of the MPG edge off (instead of 25-29MPG on the highway, I could be running 29-33MPG). Anyone has ever tried something like this?