Looking at converting an '03 325 to all-electric, but there are some
technical problems I can not figure out.

I'll be using a 350 VAC electric motor with 530nM torque, so a tranny is
not needed. The motor would essentially go where the tranny used to be.


I do however, need to gear down the rear-end to around 9:1 or 10:1. Where
in the world would I get parts to do this?

Eliminating the tranny means I lose my parking pawl and speedo. How can I
fabricate a decent parking brake? Standard parking brakes these days are
no good. I need to provide something that'll hold the car on a hill.

And where to put the speedo cable? On the bouncing driveshaft? Where to
get gears for it? What is its ratio?

Does anyone know exactly how the overdrive works? On my Jeep, overdrive
is an add-on module at the back of the tranny, and it would be nice to
have overdrive on the electric motor. Does it require pressurized
hydraulic fluid to operate? Exactly how does it work? My '99 Jeep's OD is
electronically controlled. I wonder if the newest OD units need pressurized
hydraulic fluid?

{sigh} no one ever said it'd be easy...

"Quantumstate" <chimera_god@yahoo.com> wrote

I'd look around for another website focused on electric conversions and
ask the question there.


My parking brake holds my 330xi perfectly adequately on any hill in Seattle.
You won't do any better than that.


Even on your "electronically controlled" Jeep, it probably needs hydraulic
power
to operate. Every recent OD on an automatic transmission I know about is a
planetary gearset integral with the transmission that is operated by
hydraulics.
Older ones (on '50s Chrysler products for instance) on manual transmissions
were operated by electrical solenoids (as might be your Jeep).

An electric motor DOES NOT need an overdrive.

FloydR

> I'd look around for another website focused on electric conversions and
ask the question there.

Well, of course I have. But there is simply not the raw mechanical depth
I was hoping to find, so am turning to racing forums.

Most electric conversions are quite primitive. Essentially, I am trying
to make one like a regular car.



AC electric motors do not, true, although DC motors need a tranny and OD
would be nice. For any amount of freeway driving though, overdrive would
save quite a bit of power. I am the first to think of this, but I do know
OD would be quite desirable, if technically possible. Only question is,
exactly how do they work?

Interesting project. I would disagree with your statement that you don't
need a transmission. You can't really expect to run 15000 rpm through the
stock driveshaft designed for less than half that value. So you either need
to mount the electric motor closer to the new high ratio rear end or you
need a fixed 2:1 to 3:1 reduction up front to keep the driveshaft speed in
the range it was designed for. I guess you could leave the transmission in
the car and just use 2nd gear all the time. It would be interesting to see
how long it lasted. As far as a fixed ratio gearbox, the one in the Prius
might just fit the bill and should be available in your local junk yard.

"Quantumstate" <chimera_god@yahoo.com> wrote in message
news:594979650389c95eb62b08c1ba26d162@localhost.ta lkaboutautos.com...

Max speed of the motor is 9,000rpm, but it is a good point. Anyone knoe
what the normal second-gear ratio for a 325 is?

"Quantumstate" <chimera_god@yahoo.com> wrote in message
news:594979650389c95eb62b08c1ba26d162@localhost.ta lkaboutautos.com...
Where are you going to get AC power?
Jim

"Jim" <j.n@nospam.com> wrote in message
news:_5ZVg.20480$Ij.7838@newssvr14.news.prodigy.co m...
Wouldn't he just need a really, really long extension cord?

I wish him luck. If this was easy, we'd all be able to buy one from BMW.

"Jim" <j.n@nospam.com> wrote in message
news:_5ZVg.20480$Ij.7838@newssvr14.news.prodigy.co m...

Probably a *big* inverter drive. These are dmaned expensive too, and need
much cooling. I'm still curious as to where he's going to put the (many)
batteries. I guess the original vehicle's 50/50 weight split will go to
hell.

JB

In article <4osi74Fg7l9dU1@individual.net>,
JB <JB@Nospam.co.uk> wrote:

Won't matter for a city only car - and that's all an all electric one will
be.

--
*Proofread carefully to see if you any words out or mispeld something *

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

Jim, AC power comes from an inverter, which converts battery DC to 3-phase
AC for the Siemens motor. My conversion will be along these lines:
http://www.metricmind.com/ac_honda/main2.htm

Tom, it's not that it's difficult. I am just trying to bridge that last
gap to making it like a regular car. No, this is well within BMW's realm.
Ever heard of the Solectria car? The electric S10 pickup? The GM EV1?
All dead now, thanks to Big Oil's big money buying them off. See the
movie, "Who Killed the Electric Car".

JB, battery technology has come a long way since you last checked.
Lithium ions are a fraction of the volume and weight of lead-acid, and
pack many times the energy. Check these:
http://www.gsbattery.com/lithium/LEV/index.html
... which are what was used in the Eliica supercar:
http://en.wikipedia.org/wiki/Eliica

And check out this little monster:
http://www.gizmag.com/go/6104/

Here I thought we Americans were the only ones 10 years behind the times.
Dave, electric vehicles don't have to be city-only. How's about a
trailer, with an ICE engine, which actually PUSHES the electric car on
long trips:
http://www.austinev.org/evalbum/753
... or an Insight engine/generator trailer, which provides 10kW while the
EV motor draws 7.2?

That should put the doubters to rest. Now, are there any automotive
engineers in the house, who can help with my questions?