[ausev] Wheel motors, was Re: Toyota Landcruiser conversion
Ian Ward
ian.ward at gmail.com
Thu Feb 15 03:30:38 GMT 2007
I would guess that the rotational weight is less for a hub motor than a
standard wheel as long as the total weight difference isn't too great. The
entire weight of the stator, rotor, rim and tire is unsprung, but the stator
is not rotational.
It's all fun to think about. I think for most EV drivers, the unsprung
weight difference isn't going to affect handling enough to discourage their
use - I'm guessing it will be the price and reliability. The price
difference of 4x motors, additional controller hardware, and more complex
software may eventually be reasonable because you can remove so many moving
parts (transmission/gears, drive shafts, transaxles, etc), but having those
motors unsprung will subject them to every bump in the road and it may be
hard to mitigate that kind of abuse.
- ian
-----Original Message-----
From: ausev-bounces at austinev.org [mailto:ausev-bounces at austinev.org] On
Behalf Of Aaron Richardson
Sent: Wednesday, February 14, 2007 4:41 PM
To: AustinEV News Announcements and General Discussion
Subject: Re: [ausev] Wheel motors, was Re: Toyota Landcruiser conversion
The PAX run-flat wheel that comes on the Honda Odyssey touring edition
weighs ~75lbs per wheel!! I have not noticed any unusual handling
issues driving this van, although I have not driven the non-PAX version
to compare against. Some people on the web have changed out to non-PAX
tires (weighing it at around 50lbs) and notice handling changes. I
would imagine that you can add alot of extra weight to the wheel without
creating serious issues. It probably causes more of a problem in the
efficiency and acceleration area than anything else.
Aaron Richardson
On Wed, 2007-02-14 at 15:31 -0600, Ian Ward wrote:
> I spoke to a Lotus engineer at NADA that has been involved in the
> design concept they are working on for ZAP, and he said that the
> difference in unsprung weight between the ice version of the car with
> performance disc breaks and the hub motors made by PML Flightlink
> (also used on the Mini conversion they did) is only about 14 lbs.
> Granted, any increase in unsprung weight can impact handling, but this
> easily falls within the weight difference between a performance wheel
> and stock wheel. I'm still skeptical of this claim, but until I do
> the research and add up the numbers, I can't be too critical. There
> is certainly a lot of weight in big performance discs, calipers,
> bolts, lugs and bearings, so maybe it isn't such an outrageous claim.
>
> You are still correct, though - this is not a project for a hobbyist.
> The complexity of the controller(s) for all wheel drive that takes
> turning, slippage and traction control into consideration is more than
> I would feel confident taking on.
>
> On 2/14/07, Christopher Robison <eeyore at phototropia.org> wrote:
> I think wheel motors are an interesting idea, but they present
> some
> problems for someone building an EV.
>
> First is availability. They're not really an off-the-shelf
> component
> that we can easily just go out and buy from companies like EV
> Parts and
> KTA, like normal EV motors.
>
> More importantly however, is the handling problems they cause.
> By having
> that much mass in your wheels, it becomes very difficult to
> keep the
> wheels planted on a bumpy road surface at high speeds. A wheel
> that's up
> in the air after a bump at any particular moment is a wheel
> that can't
> help with traction, cornering or braking. Google for the
> phrase
> "unsprung weight" and you'll find a lot of discussion about
> this issue.
>
> There are some current efforts to develop practical vehicles
> based on
> wheel motors and ultimately I think it could be a very good
> idea, but I
> don't believe it's a practical alternative for people doing
> their own
> garage conversions today.
>
> --chris
>
>
>
> On Wed, 2007-02-14 at 09:49 -0800, Clendon Gibson wrote:
> > Perhaps this would be a good vehicle to use wheel mounted
> electric motors in? Would that not do away with the 4WD
> transmission issue?
> >
> > ----- Original Message ----
> > From: Christopher Robison <eeyore at phototropia.org>
> > To: AustinEV News Announcements and General Discussion <
> ausev at austinev.org>
> > Sent: Wednesday, February 14, 2007 11:29:13 AM
> > Subject: Re: [ausev] Toyota Landcruiser conversion
> >
> > This could be a really fun project. I think the older
> jeep-style FJ40
> > Land Cruisers were a lot cooler than the current behemoth
> luxury SUVs
> > under the same name. A bit of attitude they're trying to
> bring back with
> > the FJ Cruiser. You probably won't find any OEM parts for
> it, but the
> > old style Land Cruisers have enough of a fan base that there
> are
> > companies making replacement parts. This typically means
> they'll be
> > available, but expensive.
> >
> > The reality is that your two questions answer each other.
> Whether or not
> > your conversion will be able to keep up with traffic depends
> greatly on
> > how much money you have to spend on it. Plan your budget
> starting at
> > about $10k for the conversion, but more if you want to
> maintain any of
> > the FJ's capabilities in off-roading etc.
> >
> > A couple things learned for certain in Nick's Cherokee
> conversion.
> > First, having a boxy vehicle with a lot of frontal area
> makes it more
> > difficult to have decent range. Second, keeping the 4wd
> parts (transfer
> > case, front driveshaft and axle) makes it even worse.
> >
> > How far is your commute? Would you be able to plug in at
> work? If
> > you're doing mostly 40-50mph, your range will be noticeably
> better than
> > having to drive 60-65.
> >
> > Bottom line: this conversion won't be cheap to do, as you
> have many
> > factors working against you: Weight, aerodynamics, obscure
> and expensive
> > parts, inefficient 4WD drivetrain. However, it would be a
> really cool
> > vehicle when complete, if enough money is spent to do it
> right.
> >
> > --chris
> >
> >
> >
> > On Tue, 2007-02-13 at 16:13 -0600, charles winningham
> wrote:
> > > Hello all,
> > >
> > > I am an aspiring electric car owner who has come into the
> opportunity
> > > to purchase a 1983 Toyota Landcruiser for next to
> nothing. I would
> > > like to buy it and convert it to electric for the purpose
> of being a
> > > commuter car but I have some concerns and I do not know
> exactly how
> > > much it would cost to do a competent conversion of this
> particular
> > > model.
> > >
> > > My main concerns are 1) will it be able to keep up with
> the speed of
> > > traffic on my commute? (does not include freeway driving
> but does
> > > include a short stretch of driving on the access road to
> MOPAC) 2) how
> > > much will it cost? (any range, however appoximate, would
> help)
> > >
> > > Thank you all for making this community happen. It's
> awesome to have
> > > something that actually enables me to do something about
> how much I
> > > hate driving a petroleum-fed car.
> > >
> > > Charles Winningham
> > > _______________________________________________
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> > > AusEV at austinev.org
> > > http://www.austinev.org/mailman/listinfo/ausev
> >
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