Add electric motor to extend range?

[ProDigit]

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?

[Stubby79]

Adding a motor(s)? Yes, it’s been done.

Using washing machine AC motors? If it’s been tried, whoever did it was probably too disappointed with the results to report on it.

You need something with some grunt. Those little motors might pull enough power on startup to claim they peak at 5hp, but that’s for moments. They’re probably rated at about 1, or at most 2 horsepower continuous. They have low starting torque. They’re not appropriate for what you’re trying to do.

Find something rated at 5hp continuous and you’re on the right track. All a little motor can do, at best, is extend your P&G by a bit.

[jakobnev]

What car are you planning to add this to?

[cRiPpLe_rOoStEr]

If I were going to work around electric motors, I'd take a look at those starter-generator units.

[ProDigit]

It would be a nice project, however, the reverse is really how a hybrid needs to run efficiently.
Ger an all electric car, and equip ot with a tiny engine, that directly drives the wheel through a reduction gear (gasolime or diesel). The thrust the tiny engine provides significantly increases electric range. And since the engine doesn't need to accelerate the car, just provide enoigh thrust to coast, getting 100mpg wpuld be an easy thing out of it.
The electric motors are there to accelerate the car to cruising speeds, and get disactivated when cruising at the fixed 30/45/60 mph speed limits of your regions, and only get activated again, when needing to overtake or speed up again.

Apparently Koenigsegg applied a similar technique in one of their newest cars, they equipped it with a tiny 400hp engine to provide extra thrust to the front wheels.
Though not with the intent of reducing emissions or increasing mpg, but with the intent to increase range.

[oil pan 4]

Find the rear wheel motors before you go any further.

[cRiPpLe_rOoStEr]

Originally Posted by ProDigit

Apparently Koenigsegg applied a similar technique in one of their newest cars, they equipped it with a tiny 400hp engine to provide extra thrust to the front wheels.

You mean the Koenigsegg Gemera? IIRC its 3-pot 2.0L is rated at 600hp.

Though not with the intent of reducing emissions or increasing mpg, but with the intent to increase range.

It was also meant as a showcase for the Freevalve camless system, which is surrounded by many claims that include its suitability to retain port-injection even with boost in order to not need a particle filter.

[oldtamiyaphile]

Easiest way would be to get a FWD with rear drive on demand (like most SUV's or my SX4), disconnect the drive shaft and splice the motor into there. Far easier than connecting to each drive shaft.

These rear axles are designed for light duty, I'd use it as a gridlock assist system, for parking, hill starts to save the clutch, that sort of thing.

[cRiPpLe_rOoStEr]

Originally Posted by oldtamiyaphile

Easiest way would be to get a FWD with rear drive on demand (like most SUV's or my SX4), disconnect the drive shaft and splice the motor into there. Far easier than connecting to each drive shaft.

Just like the Peugeot 3008 Hybrid4 worked.