Hub Motors & RTA compliance

Post by **Marcus** » Mon, 24 Aug 2009, 21:43

Hey all,

I've just been lurking for a while... waiting for the Aus dollar to get over that crazy low a while back (man, doing the maths on lithiums seriously imploded that little part of my brain that keeps contemplating my eventual EV!).

Anyhow, I'm still in the pie-in-the-sky / saving stage, which at least allows for a certain freedom in contemplating possibilities - unhindered by the inconvenience of material realities!

So I was thinking a bit about the possibilities of using hub motors. As a raw concept there's a persuasiveness and logicality to using them. I was wondering tho, even if the various mechanical & material obstacles in doing a hub motor conversion were overcome... how difficult would it be to get such a vehicle registered in NSW?

Take brakes for example... would in-hub disk brakes pass muster?

I'm guessing that the dramatic change would be deemed to amount to the construction of a new vehicle, no?

*shrugs*

Like I say, its all pie in the sky stuff... but I'd like to think that these possibilities will one day become a reality for some amoungst us!

So thoughts anybody?

Post by **Richo** » Mon, 24 Aug 2009, 22:13

Marcus wrote:how difficult would it be to get such a vehicle registered in NSW?
would in-hub disk brakes pass muster?

I would expect that the vehicle would have to have brake tests.
You may also need a mech cert saying that they are appropriate for the vehicle.
All possible just at more expense.

atm If I was contemplating putting hub motors in a car then I would also contemplate 4 standard induction motors with CV's.

For example a 3kW 4-pole induction motor wired in 230V delta running at 400V
Would be 3kW x 1.73(delta) x 3.5(Tm/Tn) x 4 wheels = 72kW.
These are "off the shelf" induction motors - NO REWIRING.
They can be as cheap as $350 ea so $1400 for 4 motors.

The mechanical brakes stay the same.
The unsprung weight is not increased.
full regen.
Minor effeciency loss through small transmission system from motor to wheel.

Considering I doubt you could get ONE hub motor at 18kW ea for under $1400.
The hub-motor brakes would only be a minor issue in comparison.

Post by **Marcus** » Mon, 24 Aug 2009, 22:31

Richo wrote: The mechanical brakes stay the same.
The unsprung weight is not increased.
full regen.
Minor effeciency loss through small transmission system from motor to wheel.

Definite advantages!

Post by **Richo** » Mon, 24 Aug 2009, 22:44

Don't tell anyone you could get them rewound to 140kW!

Yeah imagine a small car with 140kW.
That's better than the new "Sport" corolla with 100kW in so many ways.

Post by **Marcus** » Mon, 24 Aug 2009, 23:09

man i love topic drift... from a thread about legal compliance to to you putting the devil's thoughts in my head!

Post by **Richo** » Mon, 24 Aug 2009, 23:30

Yeah sorry
The AC induction system has issues as well.
Like space for the motors.

Also what hub motor has the disks in the hubs?
I would think that this would have massive heat problems.
So the disk would still have to be outside the hub.
The hub with 100% regen alone would not be enough for braking.

Post by **Richo** » Mon, 24 Aug 2009, 23:38

Here I started a new thread on a cheap AC ICV HERE

Post by **acmotor** » Tue, 25 Aug 2009, 01:56

Hub motors, that I have seen commercially, are rather light on when it comes to load rating or braking capacity.

If you were to fit hub motors to a conversion they would need to be manufacturer or approving engineer certified to at least match the original axle load ratings and braking capacity. e.g. in the order of 800kg load per wheel and braking for a 1000kg vehicle from 100kmph in a few seconds.

The suspension tuning would logically be a point the approving engineer would consider also (unsprung mass).

Having said that, there is no reason that a suitably rated (those being the key words) hub motor was not used in a conversion. I would expect DPI/RTA to approve if it was approvable !

If you find a suitable Hub motor on the market let us know !

Post by **Marcus** » Tue, 25 Aug 2009, 16:00

i haven't done a huge amount of research into what's commercially available... but was somewhat inspired by this article:
Electric Mini: 0-60 in 4 Seconds: It Has Motors In Its Wheels

I did notice some hub motors available from China - but mostly way underpowered for anything besides golf carts! But I am still trying to look further into it, so I'll keep you posted!

Post by **Marcus** » Tue, 25 Aug 2009, 16:15

While skeptical about some of these chinese suppliers... would something like this do the job???

6-10KW Brushless hub motor

There was another supplier, with whom email conversations seem to take an eternity, who even had 20kw versions available... I'm still waiting for an email with the specs on that atm. I'll post up those details when they arrive if you like.

Honestly, I've got no particular expectations on the viable hub-motor front - it just seemed worth investigating.

Post by **Richo** » Wed, 26 Aug 2009, 00:03

Here is one you can get straight from Kelly controllers.

Post by **Richo** » Wed, 26 Aug 2009, 00:05

Marcus wrote: i was somewhat inspired by this article:
Electric Mini: 0-60 in 4 Seconds: It Has Motors In Its Wheels

Hey do you notice that they have chocked the wheels so it doesn't roll away

Post by **antiscab** » Wed, 26 Aug 2009, 00:08

This one might be more usable.

The guy who makes it (or rather owns the company that has the design rights) says a car version with roller bearings is under development.

Matt

Post by **Squiggles** » Wed, 26 Aug 2009, 02:26

Richo wrote: Here is one you can get straight from Kelly controllers.

That is a whole lot of unsprung weight.
Inboard motors and brakes with drive half shafts has just got to be a better solution.

Post by **Tritium_James** » Wed, 26 Aug 2009, 02:48

20kg is not necessarily the end of the world with unsprung weight, but for only 6kW? Pretty nasty...

Post by **Tritium_James** » Wed, 26 Aug 2009, 02:49

Richo wrote:Hey do you notice that they have chocked the wheels so it doesn't roll away

Well it doesn't have any hydraulic brakes at all, so they probably left out the handbrake too...

Post by **juk** » Tue, 17 Nov 2009, 03:41

Here is one that has some potential, and it's aussie too:

http://www.hybridauto.com.au/2.html

Post by **HeadsUp** » Wed, 30 Dec 2009, 04:00

wheel motor from the US " Hi-Pa Drive "

not much detail on specifications or efficiency anywhere

anutha wheel motor

Post by **antiscab** » Wed, 30 Dec 2009, 22:43

broken link.

btw, that hub motor has been around for years. i still haven't seen anything from it actually working.

Matt

Post by **HeadsUp** » Wed, 30 Dec 2009, 22:49

the link is okay , its their website which is down

i agree , they showed no details or specifications .... could be another prop from the dodgy brothers Inc.