Tuesday, February 03, 2009

Motors, Transmission, Wheelmotors Oh My!

In my mind, there seems to be 2 ways to convert an EV.

  1. Take out the ICE, petrol tank, exhaust system, hook an electric motor up to the drive shaft on the (manual) transmission and stuff it with batteries
  2. Take out the ICE, petrol tank, transmission, differential, drive shafts, brakes1, petrol tank, and fit a wheelmotor to each wheel.

Option 1 is obviously simpler, but introduces plenty of losses with transmission and differential gearing.

Option 2 is more complex, but rids the car of a lot more weight, and gives no gearing loss, along with simple 4-wheel drive. However, it does change (increase) the “Unsprung weight” of the car (A bad thing). Oh, and (at the moment) there is the not-so-small issue that there are no wheelmotors available on the market at the moment.

There are a few companies advertising wheelmotors, and they all have glowing stories (and video, in some cases) of their wheelmotors in action. But none are available. Let’s list the ones I’ve found:

PML Flightlink’s Hi-Pa Drive.

I’ve been watching this one for a while. They used to have a lot of technical details on this system on their site, including nice PDFs. But now the company is in administration, and their Hi-Pa Drive link goes to a very pretty site that is sadly lacking in technical information. They also used to state that they were not going to sell to individuals. While that piece of text is gone from their site, important details are still missing, and it’s not looking good for prospective EV converters.

E-Traction’s TheWheel.

(You’ll have to find it on E-Traction’s frames-infested site. It’s under “The-Wheel direct drives” –> “SM450”)

This is apparently up and running on a few busses in the Netherlands, and while they have pictures up on their site for a car-sized unit (The SM450/1), it’s not actually been made in any working form yet. They, too, will not sell to individuals.

TM4’s “Electric Corner Module

(I kid you not – It’s meant for using to supplement existing ICE drive systems, but can (as they admit) be used as a totally electric drivetrain.)

This Canadian company (Quebecois, of course) shows these wonderful systems. The key phrase here, however, is that “Our experienced design team will work closely with you to meet your specific needs for an AWD drivetrain, using electric wheel motors or any other configuration, whether centrally mounted or not.”

In other words, call us, Mr. motor industry executive, and we will quote you a nice, exorbitant price for a complete system, including assembly-line tooling and the like. Small-batch buyers (Like individuals and small businesses), you’re not welcome.


And that’s it. There are no other makers of automobile-grade wheelmotors, anywhere. Why is this? Is it that these three companies, between them, hold the patents to effectively choke anyone else out of making wheelmotors? Is there no other use for a small, efficient, and agile motor like these? You would think, with EVs, PHEVs, Hydrogen Fuel Cell’d EVs and the like, there would be more demand for such a groundbreaking technology.

1. Yes, brakes. With wheelmotors, you can Regen down to 0MPH, and they have a small mechanical brake for parking.

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