The feasability of a motor on the rear axle?

i was checking out Kelly Controllers and ran across qs-motor.com ... it looks like they have started selling automobile-sized hub motors around 10kw, you can even get a rim attached.

This may be wrong but i have read somewhere that a 1 hp electric motor is equivalent to about a 3 hp internal combustion engine, so if you had two 12kw hub motors it might be around equivalent to an 72kw ice motor, or about 97 horsepower.

if i understand correctly, the prius AWD rear motor is about 5kw. Two hub motors of 12kw would be almost 5 times as much power.

 

Point #1 if you bought a Prius for power, you bought the wrong car.

Point #2 What will power the motor? MG/2 is already able to use more power than the HV battery can produce, so unless you have a new power source, more motor is not going to help.

 

This is only an approximation for low-RPM torque. Any other application of it is garbage.

I've seen it on electric lawnmowers, first as "same torque as X HP gas engine", then shortened to merely "X HP". The later should be prosecuted as fraudulent advertising.

Electric motors tend to have high torques at low RPM, while ICEs have low torques at such speeds. That is why electrics can be direct-drive in uses where ICEs need transmissions. Electrics can do standing starts with no minimum RPM, where ICEs need to be running first, then be connected through some sort of soft engagement that allows the motor to maintain its minimum operating RPM.

12 kW x2 = 24 kW = 32 HP. Extrapolating that to 97 horsepower is pure garbage.

 

The 2019 Prius e-AWD system employs a disconnect above 6mph and is not considered full time. Toyota’s aim was to appeal to the cold weather crowd as a marketing strategy. In the northern areas of the USA, AWD drive cars (Subaru, CR-V, and 4WD trucks) are the norm.

So, to make e-drive feasible, it obviously has to disengage at some time to conserve battery energy. It was not designed to make the Prius a Hot Rod but to fill a niche where extra traction is a favorable selling point.

 

Interesting that it disconnects above 6mph.
Does anyone know how it works for the RAV4 AWD? At what speed does the rear drive disengage on that one?

 

This one made the rounds in another, similar thread.

Still has the same problems with needing its own battery, control & charging system, and I have real doubts about longevity out on dirty real world streets.

 

Forklift motor? Drag strip?


PRIUS SRT8 - Toyota Prius with a Supercharged SRT Hellcat V8 Engine Swap

 

The more conventional AWD vehicles usually disconnect at around 35 MPH to save the fluid coupling from overheating. Also, most have temperature sensors that will disconnect the fluid coupling if temperatures exceed a safe limit.

 

The RAV4 hybrid AWD employs a electrically driven rear axle, no fluid coupling.

 

The AWD hybrid is in a whole different ball park than “conventional” AWD. I would make a guess that the dedicated rear wheel drive motor senses the rear wheels slipping and then compensates until it is no longer needed. At that point it would disengage when traction is achieved. As for the disengagement speed limit... probably ECM controlled. At what speed...???