EV Digest 4319
Topics covered in this issue include:
1) Re: probably need new shocks/springs (struts) on the VoltsRabbit,
also drilling polypro
by Seth Allen <[EMAIL PROTECTED]>
2) Re: IRS Replacement
by "Dave" <[EMAIL PROTECTED]>
3) Re: Searching for cup rotor
by Neon John <[EMAIL PROTECTED]>
4) Re: Transfer case as transmission
by Rush <[EMAIL PROTECTED]>
5) Re: IRS Replacement
by "Joe Smalley" <[EMAIL PROTECTED]>
6) Re: Is this possible?
by "Joe Smalley" <[EMAIL PROTECTED]>
7) Re: Is this possible?
by "David Roden" <[EMAIL PROTECTED]>
8) Re: Is this possible?
by Quin Pendragon <[EMAIL PROTECTED]>
9) Re: An AC style "bypass"?
by "David Chapman" <[EMAIL PROTECTED]>
10) Re: Contactor controller, Was:RE: Mechanical PWM Controllers
by Justin Southam <[EMAIL PROTECTED]>
11) Re: Contactor controller, Was:RE: Mechanical PWM Controllers
by Justin Southam <[EMAIL PROTECTED]>
12) Forbes Magazine: GM Hydrogen article.
by "Lawrence Rhodes" <[EMAIL PROTECTED]>
13) Re: Motor Choke Question?
by "Mark Hanson" <[EMAIL PROTECTED]>
14) Re: Ballsy hybrid
by John Wayland <[EMAIL PROTECTED]>
15) Re: Contactor controller, Was:RE: Mechanical PWM Controllers
by jerry dycus <[EMAIL PROTECTED]>
16) Motor/controller combination
by [EMAIL PROTECTED]
17) Tennant Etek
by Mark Hastings <[EMAIL PROTECTED]>
18) Re: IRS Replacement
by Reverend Gadget <[EMAIL PROTECTED]>
19) Re: An AC style "bypass"?
by Lee Hart <[EMAIL PROTECTED]>
20) Re: Tennant Etek
by pekka <[EMAIL PROTECTED]>
--- Begin Message ---
The srsvw springs aren't for lowering, as I noted- they are for stock
ride heights. As for stiffening: increasing the spring rate is the
point, as the load is greatly increased. I suppose if he wants, he can
get the same springs as before, but it appears they sagged?
Seth
On Apr 27, 2005, at 9:30 PM, Electro Automotive wrote:
Sorry, Chuck, been buried in email here lately. Maybe something to do
with gas prices, hmm?
As for drilling your battery box, yes, regular drill bits are fine.
What was said earlier about letting the drill weight do the job is
good advice.
For the springs: shine racing services (www.srsvw.com) offers all
kinds of spring rates for stock ride heights for rabbits and golfs.
You can mix and match, I think they were $60 a corner a few years
ago. A set of Bilstein shocks and struts (the HD are nice) are good
too. But the best price for those used to be at RD Enterprises, now
www.shox.com
These are unlikely to be appropriate. They are probably designed for
lowering or stiffening, not for added load carrying ability. Yes,
Chuck, we can get you more of the rear springs. We have them custom
wound. $150 each. These ARE specced out for the extra weight.
The HD Bilsteins will be a better match for you heavy car with high
spring rates.
These are good shocks, may cost more than the KYB gas shocks in the
kit, though.
Mike Brown
Electro Automotive POB 1113 Felton CA 95018-1113 Telephone 831-429-1989
http://www.electroauto.com [EMAIL PROTECTED]
Electric Car Conversion Kits * Components * Books * Videos * Since 1979
--- End Message ---
--- Begin Message ---
Inboard brakes (Jag XKE) are cool, until you have to replace the brakes.
Then you curse them to high heaven.
David C. Wilker Jr. USAF (RET)
Children need love, especially when they do not deserve it.
- Harold S.
Hulbert
----- Original Message -----
From: "Christopher Robison" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Wednesday, April 27, 2005 9:51 PM
Subject: Re: IRS Replacement
Probably not the answer you were looking for, but I just had to share
this... I have seen a few IRS setups you can buy and retrofit into your
car, but this is by far the most gorgeous one I've come across, made by
Wayland's friends at Dutchman Motorsports (from whom I'll be buying much
of my driveline, as it turns out -- thanks for the tip, John!!):
http://www.dutchmanms.com/1_irsnav.html
If you were wanting to build something, you might take some inspiration
from how this is designed. Note the inboard brakes (maybe more obvious
from the side view), making the wheels very lightweight. This would be
critical if you were going to use wheel motors. You'd want a design very
much like this, but instead of the differential in the center, you'd have
the brakes there, very close together but not connected to each other.
Just outside of the brakes you'd have your wheel motors. All of this would
be mounted to the frame. Then you'd have your half-shafts going to the
wheels. Dutchman sells the wheel hub carriers and half shafts separately,
and I figure they'd probably be willing to work a deal with you, if you
just wanted to buy the brakes, support arms and other framework stuff.
It'd be up to you to design the center structure (motor-brake-brake-motor)
such that the mounting points would be compatible.
Dunno ... just a thought. For what it's worth, I think this would be
*really* cool.
--chris
Bill Dennis said:
Is there some place on the web I can read about how to replace the
Independent Rear Suspension on a car to have wheel motors (or hydraulic
motors, as Lee Hart recently suggested)? Rear suspension on the car is
currently just the simple old: Strut, Control Arm, Suspension Arm and
Suspension Knuckle.
Thanks.
Bill Dennis
--- End Message ---
--- Begin Message ---
On Wed, 27 Apr 2005 13:19:25 -0700 (PDT), Rod Hower
<[EMAIL PROTECTED]> wrote:
>Many electric scooters have a 3.5" OD cup rotor that
>is part of a Brushless DC motor/control.
>The rotor is a steel cup with magnets glued on the
>inner surface. The stator is actually inside this cup
>(kind of an inside out motor).
>back in the late 80's there was a BLDC cup rotor that
>measured 6" OD and 2" high. This was used on a
>multiplatter disk drive for data backup in computer
>systems.
>
>Does anybody know who made these? Are these larger
>cup rotors used on any of small EV's being sold now?
If you only need one or two for a personal project, you might check
out some of the japanese dirt bike flywheels. The alternators were
made (and maybe still are, I'm out of touch nowadays) with exactly
that same construction. In fact, Yamaha made a single cylinder 500cc
"thumper" street bike that I converted to electric start by driving
the alternator as a BLDC.
Some of these flywheel/alternators were huge. Seems like the one on
that Yamaha weighed over 20 lbs.
---
John De Armond
[EMAIL PROTECTED]
http://www.johngsbbq.com
Cleveland, Occupied TN
--- End Message ---
--- Begin Message ---
----- Original Message -----
From: "Ryan Stotts"
Sent: Wednesday, April 27, 2005 9:27 PM
Subject: Re: Transfer case as transmission
>I just now found out about this one.
>
> Is this what you remember?
>
> http://www.usgear.com/dual_range.htm
>
> Or:
>
> http://www.usgear.com/v2od.htm
>
Right, when I was rving, I heard about them and almost put one on my gas 250
which didn't have the power to pull a 9000 lb 5th wheel, instead I got a diesel
250...
In any case I have reconsidered the gearing on the conversion I'm doing. It
just makes sense for me to do a standard conversion, use all the existing parts
so that I use it as a learning experiment. So I'll keep the standard
transmission and use the gears as I need them.
But on the next conversion I do want to take out the transmission and use a
transfer case with a IRS on the rear end.
Rush
--- End Message ---
--- Begin Message ---
I looked at the photos and wonder how the camber is controlled. There were
no photos of the bottom of the shock. Is it being used as a strut to control
the camber?
It is very important to make sure all the lateral struts (including the half
shafts) are parallel and the same length to control the geometry. If they
are not, the camber will change as the wheel moves up and down relative to
the frame, or the half shaft will bind. There are some ways the designer can
get around these limitations but just putting a motor outboard of the brake
and moving the inner U-joint a few inches outboard will make it bind. The
inner suspension pivots must be moved to compensate.
Joe Smalley
Rural Kitsap County WA
Fiesta 48 volts
NEDRA 48 volt street conversion record holder
[EMAIL PROTECTED]
----- Original Message -----
From: "Christopher Robison" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Wednesday, April 27, 2005 9:51 PM
Subject: Re: IRS Replacement
> Probably not the answer you were looking for, but I just had to share
> this... I have seen a few IRS setups you can buy and retrofit into your
> car, but this is by far the most gorgeous one I've come across, made by
> Wayland's friends at Dutchman Motorsports (from whom I'll be buying much
> of my driveline, as it turns out -- thanks for the tip, John!!):
>
> http://www.dutchmanms.com/1_irsnav.html
>
> If you were wanting to build something, you might take some inspiration
> from how this is designed. Note the inboard brakes (maybe more obvious
> from the side view), making the wheels very lightweight. This would be
> critical if you were going to use wheel motors. You'd want a design very
> much like this, but instead of the differential in the center, you'd have
> the brakes there, very close together but not connected to each other.
> Just outside of the brakes you'd have your wheel motors. All of this would
> be mounted to the frame. Then you'd have your half-shafts going to the
> wheels. Dutchman sells the wheel hub carriers and half shafts separately,
> and I figure they'd probably be willing to work a deal with you, if you
> just wanted to buy the brakes, support arms and other framework stuff.
> It'd be up to you to design the center structure (motor-brake-brake-motor)
> such that the mounting points would be compatible.
>
> Dunno ... just a thought. For what it's worth, I think this would be
> *really* cool.
>
> --chris
>
>
>
> Bill Dennis said:
> > Is there some place on the web I can read about how to replace the
> > Independent Rear Suspension on a car to have wheel motors (or hydraulic
> > motors, as Lee Hart recently suggested)? Rear suspension on the car is
> > currently just the simple old: Strut, Control Arm, Suspension Arm and
> > Suspension Knuckle.
> >
> > Thanks.
> >
> > Bill Dennis
> >
> >
>
--- End Message ---
--- Begin Message ---
Type of motor is irrelevant.
DC works as well as AC.
Sheer Pullen did this from Seattle to Woodburn (and back) a few years ago
with Evercells and an AC motor.
One of the design goal of the PFC charger was to control the AC waveform
from the genset to maximize the watts from the genset without overloading
it. When you set a PFC charger for a certain number of line amps, it stays
there regardless of the battery voltage. The genset current stays constant
even if the controller sags the batteries to half voltage.
Joe Smalley
Rural Kitsap County WA
Fiesta 48 volts
NEDRA 48 volt street conversion record holder
[EMAIL PROTECTED]
----- Original Message -----
From: "Ryan Stotts" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Wednesday, April 27, 2005 8:05 PM
Subject: Is this possible?
> Battery pack, controller, DC motor.
>
> Driving down the street. While at the same time, the PFC is plugged
> into a generator and charging the pack.
>
> I clearly remember reading on this list a couple months ago it being
> said that was not possible. Something to do with the way the
> batteries work..
>
> Now I am confused. Possible or not?
>
--- End Message ---
--- Begin Message ---
On 28 Apr 2005 at 11:49, Quin Pendragon wrote:
> the 'not possible'
> stuff was about driving a car off the batteries while the batteries
> were being charged, which is obviously not possible since current can
> only flow into *or* out of a battery, not both ways at once.
Unless I'm misunderstanding you, this isn't an accurate statement.
Edward Ang's post addresses the matter pretty well if you extend it a
little. Just as you can pour water into a glass at the same time you're
siphoning water out of it, you can indeed charge a battery while you're
drawing current from it. Otherwise, awful things would happen if you opened
your EV's door and the dome light came on while the charger was operating.
David Roden - Akron, Ohio, USA
EV List Assistant Administrator
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--- Begin Message ---
On 4/28/05, David Roden <[EMAIL PROTECTED]> wrote:
> On 28 Apr 2005 at 11:49, Quin Pendragon wrote:
>
> > the 'not possible'
> > stuff was about driving a car off the batteries while the batteries
> > were being charged, which is obviously not possible since current can
> > only flow into *or* out of a battery, not both ways at once.
>
> Unless I'm misunderstanding you, this isn't an accurate statement.
>
> Edward Ang's post addresses the matter pretty well if you extend it a
> little. Just as you can pour water into a glass at the same time you're
> siphoning water out of it, you can indeed charge a battery while you're
> drawing current from it. Otherwise, awful things would happen if you opened
> your EV's door and the dome light came on while the charger was operating.
Umm... I think there's somewhat of a miscommunication. Key words there
were *off the batteries* - as in, the batteries were supplying some of
the motive force for the car. The car can still drive but if the
batteries are being charged, then all of the motive power must come
from the generator, with some left over to charge the batteries.
As I said, you can charge the battery while drawing electricity from
the battery+generator system, but unless the electrical power you're
drawing off comes entirely from the generator, you will be
*discharging* the battery even though the charger is on. Possibly some
electrons from the charger will still go into the battery, but overall
more charge will be drawn from the battery than is going into it.
With your glass analogy, you can indeed siphon water out of it while
you're pouring water into it, but unless you're pouring the water in
faster than it's being siphoned out, the glass won't be getting any
fuller (being charged).
> David Roden - Akron, Ohio, USA
> EV List Assistant Administrator
>
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>
--- End Message ---
--- Begin Message ---
Quin,
This is along the lines of something I had given consideration last year and
was discussed on the list then. Sparked by me getting a 5 kw motor generator
salvaged out of an ICE driven welder during Dennis B's move. At first I
didn't think much of it, just thought it was a clunky old genset head but
when I pulled the end cover off it looked very similar to the hunk of pig
iron that Rich scored to use as his dyno, just in minature. Has a commutator
as well as slip rings. AC/DC on the same shaft!! I had thoughts that it
might be powerful enough for a small EV conversion maybe like a VW. Actually
found another identical unit with a burned field a couple weeks later,
salvaged the armature and brush rigging out of that one for spare parts.
After looking at it and realizing how many other things I had to do first
and how I don't know what to use for the AC controller, I just parked it on
the "potentially useful" shelf and went on. Maybe you can find one like it
in your area? Check out welder repair places. I believe it was a Miller,
probably 60's 70's era. If you find one like mine you will have to build an
end bell with a shaft brg as the unit originally bolted directly to and was
supported on that end by the ICE. I am a little slow sometimes but I finally
figured out the connection between what Dennis does for a living and why he
goes so fast on the track. David Chapman
Arizona Electropulsion / Fine-Junque
http://stores.ebay.com/theworldoffinejunque
----- Original Message -----
From: "Quin Pendragon" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Wednesday, April 27, 2005 7:51 PM
Subject: Re: An AC style "bypass"?
> No, no, it's a hybrid. It's still an AC motor at lower speeds/powers,
> but it's a brushed DC motor when you want every possible watt out of
> it.
>
> Ask Victor what AC motors are good at, and he'll tell you: Finesse,
> simplicity, reliability, efficiency. Convenience. Under normal use
> such a hybrid motor will be exactly that - possibly even using the
> same Siemens inverter/motor combo that Victor uses.
>
> Ask John Wayland what a DC motor connected straight to a 200+V battery
> pack is good at - I think I know what he'll say: Breaking the rears
> free at 70mph, beating Dodge Vipers, giving you a good solid kick in
> the pants.
>
> Now, combine the two with an external (to the motor) commutator-based
> inverter which can be switched in and out. You can have the best of
> both worlds at minimal extra cost and weight. No such 'serious
> silicon' and it's attendant high cost involved. No need for 600V
> battery packs (although I'm sure they'll arrive soon enough).
>
> (Apologies if I've misrepresented either John or Victor's views here -
> this is just based on what I've read in their posts, if I'm wrong I'm
> sure they won't hesitate to let me know ;)
>
> On 4/28/05, Rod Hower <[EMAIL PROTECTED]> wrote:
> > "supply big power DC to the commutator, which in turn
> > > generates
> > > (somewhat manky) AC. "
> > That's a DC brush motor, not an AC induction motor.
> > No need to add brushes to the AC motor, just bigger
> > silicon devices.
> > If you want big amps on the AC motor you'll need some
> > serious silicon, which is not cheap.
> > I think in the next 5 years this will be possible and
> > competitive, expecially with high voltage.
> > Maybe an 800Vdc pack with a 1600Vdc rated inverter?
>
--- End Message ---
--- Begin Message ---
Hi Lee and All,
Lee wrote:
>For a given motor, the PIC can predict what current it will draw by
>knowing its present rpm and the voltage you plan to apply. So
>technically, you don't need a current sensor; just an RPM sensor. I'd
>include one anyway, just as a backup system in case something goes
>wrong. If you're a clever programmer, the PIC can then figure out the
>motor's rpm-vs-current relationship for itself.
>
I'm more engineer than programmer so expect the controller design to
reflect that.
I recall from PWM controller threads that current limiting is often not
controlled by software because of risk of glitch or delay. A contractor
controller is obviously much less sensitive to over current than a PWM
controller but i'd rather the current limit activates then notifies the
PIC. Same with the rev limiter.
>The life of a contact is on the order of 100,000 cycles at rated load.
>So, you don't want to operate them needlessly or you'll wear them out
>sooner. There's no need to use the resistors except for starting, unless
>you have a very high-powered vehicle and/or large voltage steps.
>
I hadn't considered contact life. 2 thoughts spring to mind. The contactors
would close under load but the idea is the main contactor would be open
when these contactors open, i assumed most wear(arcing) would occur on
opening. Or replace them with SCRs, they would turn off with the main
contactor.
>
>You shouldn't need the resistors except for a few seconds when starting
>from a dead stop. This won't produce enough heat to be worth trying to
>put in your cabin.
Was only half serious about this :-).
>
>> I'm planning a 96v system. 24/48/96V.
>
>With 2 resistor steps, this should be fine. Especially if you also have
>a transmission.
Yes, 5 speed. Do you think a 144volt (36/72/144) 3 step system would be
practical. I think the 72 to 144v step is just too wide. I'm using 12
batteries so 120v is not an option.
>> Oil filled main contactor will be only contactor switching under
>> load.
>
>Why oil-filled?
I thought this contractor would be repeatedly and often opening under load
and this would minimise contact damage(arcing).
>You can get diodes a lot bigger than this if needed! Look at
>International Rectifer's website.
Thanks, will check it out.
>> At full voltage the 2 diodes still in circuit could be bypassed
>
>There shouldn't be any diodes in the circuit at full voltage -- just
>contacts and batteries.
I drew a circuit with 4 batteries with positives to anodes of 4 diodes,
cathodes commoned to main contactor. Battery negatives to cathodes of 4
diodes, anodes commoned for negative motor connection. Contactors from
bat1+ to bat 2-, from 2+ to 3-, 3+ to 4-. Battery 1 negative and battery 4
positive can be connected without diodes but this would upset current sharing.
>> While you don't get current multiplication like PWM at low motor
>> voltage at 1/4 battery voltage you do have 4 batteries in parallel
>> so 4 times the current available so the effect is similar.
>
>Right. It multiplies current; just not the same way as a PWM controller.
>But the consequences are the same (1/4th voltage means 4 times the
>current).
>
>> I'd love to hear how a contactor car is driven. I.E. When travelling
>> at speed would battery voltage vary between full and off or full
>> and half to maintain speed. Accelerating through voltage steps and
>> gears.
>
>You've pretty much got it. To drive at a given speed, you need a
>particular value of torque. This requires a particular motor current,
>which in turn requires a particular motor voltage.
>
>With a contactor controller, you can only set the motor voltage in
>discrete steps. If you want something in between, then you have to cycle
>back and forth between steps. For instance, if 55 mph requires 55v, and
>your contactor controller only provides 24v, 48v, or 96v, then you cycle
>back and forth between 48v and 96v steps.
>
>With a PM motor (Lynch, Lemco, Etek, etc.), you'd get rather abrupt
>lurches in speed as you switched voltages. This is because a PM motor
>fights to run at exactly the speed commanded by the voltage. A 2:1
>voltage change can cause a 100:1 current change, and this causes drastic
>changes in torque. It would be like driving a normal ICE car where you
>could only operate the gas pedal as an on/off switch -- drastic
>accelleration followed by drastic engine braking.
>
>But with a series motor, the steps are quite gradual. A 2:1 voltage
>change only produces about a 2:1 torque change. This is only enough to
>cause mild accelleration and mild decelleration. Thus with a series
>motor, you only need to switch the voltage up/down a few times a minute.
>--
Thanks, i'm using a series motor, this makes me much more confident that
this will work.
Justin
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--- End Message ---
--- Begin Message ---
Hi Ryan and All,
At 18:35 27-04-05 -0700, Ryan wrote:
>Basically you'll always end up with a finite number of cruse speeds.
>For example: Step1-5mph, 2-10mph, 3-20mph, 4-40mph, 5-60mph, 6-80mph.
Any more than 3 steps (1/4,1/2,full volts)is ambitious. Thats a lot of
batteries,cable and contactors/diodes.
>... so the accellerator is a "Target Speed" not a "Raw Step Setting".
I've heard that pedals where position is proportional to vehicle speed dont
feel intuitive, but i have not experience of this.
>Anyway, good luck,
Thanks.
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--- Begin Message ---
http://www.forbes.com/home/forbes/2005/0425/078.html
--- End Message ---
--- Begin Message ---
Hi Lee, I thought an additional choke was for start-up, to make it smoother
with those high current pulses initially and to keep the controller out of
current limit on start-up.
Mark
----- Original Message -----
From: "Lee Hart" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Wednesday, April 27, 2005 6:20 PM
Subject: Re: Motor Choke Question?
> Marvin Campbell wrote:
> > So I notice that this car has a couple of big, honkin' motor chokes
> > on the armature leads. Reading this list I never hear about anybody
> > using motor chokes in their set-ups. Why is that?
>
> Because it still works without them. Not as well, but not so you'd
> notice. It's like saying, "My wheels are held on with 5 lug nuts. I lost
> one and the wheel didn't fall off. Can I leave it off?"
>
> The chokes reduce RFI and improve range and efficiency a bit.
> --
> Ring the bells that you can ring
> Forget your perfect offering
> There is a crack in everything
> That's how the light gets in
> -- Leonard Cohen, from "Anthem"
> --
> Lee A. Hart 814 8th Ave N Sartell MN 56377 leeahart_at_earthlink.net
>
--- End Message ---
--- Begin Message ---
Hello to Dave and All,
Dave Cover wrote:
> I was on my way home from work today and I ended up behind a little gold car
> at a light. Nothing
> special, but I noticed that it was a Prius...But what caught my eye
> was the see through window sticker, just below the brake light, in the top
> middle of the back
> window.
>
> "Eat my Voltage"
Yes, it's a cool sticker...I've got a couple of them that will find their way
onto my race
EVs. Just
for trivia sake, those stickers have come with every Prius sold in the US since
it was introduced
here in 2001. Most folks opt to not put them in the window, or, remove them if
the dealer
had already
installed them.
It's too bad Honda doesn't have the same sticker, as affixed to the back window
of the new
255 hp
Hybrid Accord, with its low 6 second 0-60 time thanks in part to its electric
motor that
adds an
extra 100 ft. lbs. of low end torque to the potent V6, the car can back up that
proclamation.
See Ya....John Wayland
--- End Message ---
--- Begin Message ---
Hi Lee, Justin and All,
--- Lee Hart <[EMAIL PROTECTED]> wrote:
> Justin Southam wrote:
> > I'm planning a contactor controller with current
> limiting, rev
> > limiting, and maybe cruise control :-), and other
> yet to be
> > discovered features. 2 resistors with temp
> monitoring and possibly
> > force cooling (cabin heat :-) and a PIC for
> housekeeping...
> > PIC controls throttle, this and current limit
> should stop full
> > voltage at motor while stopped. RPM feedback could
> stop voltage
> > increase while rpm is too low. Current limit and
> rev limiting
> > have direct control of the main contactor.
Sounds complicated and will slow down getting your
EV on the road.
For current limiting you can do it easier just by
correctly selecting your battery wire size and always
having a resistor or 2 as your first speed so to get
EMF built up in the motor so it isn't a direct short
before going without the resistor.
> > Both resistors will be in circuit each time the
> voltage increases and
> > bypassed sequentially and automatically after a
> few seconds.
That by itself will limit current enough.
How I would do a contactor controller is use the
go pedal for 3-5 speeds, first a resistor or 2, then
batt voltage, then 1/4 to 1/2 field weakening or both.
Next use a series/parallel of the batts in 2 or 3
stages like shifting a transmission.
This gives you current limiting, fairly smooth
acceleration and 9-12 speeds with a minimium of
contactors especially if you use diodes though they
have their costs too.. the lower power you are, the
fewer speeds you need.
I like using small amounts of field weakening so
to get speeds between S/P ones and to increase motor
rpm for a given voltage so to use a higher gear ratio
increasing acceleration and reducing current draw
especially in hilly areas.
I also like to use as low a voltage as possible to
greatly lower charging, contactor, motor and battery
costs. 72vdc is great as the cost is very low with it
for all these things. The ability to use 2 surplus
forklift motors, A89's, gives great torque at a very
low cost.
To cruise control just use the batt voltage or
field weakening near the speed you want, While it
won't be exact, it works well. You could replace the
go pedal with a dash switch and a relay hooked to the
brake light power.
You could replace 1 of the batt S/P with 2 motors
S/P for much higher start up torque or even more
speeds. This in many lighter EV's can eliminate the
transmission.
Another, more simple way for a CC system is using
several batt packs like 12/24 one for start up and
assessory power then say a 36/72 or 48-96 vdc pack for
you long range, higher speed pack. You can subsitute
the high voltage S/P with 2 motors S/P still using the
3 way go pedal.
This would work especially well if running AirCon
off the lower voltage with an inverter or straight for
heating. While it would require 2 chargers, they would
be inexpensive ones.
And if you run your main pack low, you could limp
home or to a plug with the low voltage pack saving
your batts from damage.
>
> You shouldn't need the resistors except for a few
> seconds when starting
> from a dead stop. This won't produce enough heat to
> be worth trying to
> put in your cabin.
>
> > I'm planning a 96v system. 24/48/96V.
>
> With 2 resistor steps, this should be fine.
> Especially if you also have
> a transmission.
>
>
> > I have drawn a circuit which has 4 batteries, 8
> diodes and 3
> > contactors for 1/4, 1/2 and full voltage. I
> suspect it is a
> > recollection of Lee's rectactor circuit.
>
> ...which is in turn a recollection of many others.
> The rectactor has
> been around at least a few decades now.
>
> > The largest diodes I have so far located here are
> 400A rms @120C.
>
> You can get diodes a lot bigger than this if needed!
> Look at
> International Rectifer's website.
Lee,
How big of diodes would you need for momentary
surges of say 600 amps peak with a normal running of
say 150 amps? where is a good place to buy them cheap
either new or surplus?
Or would you use them where they would normally only
be used in parallel thus only need to be 1/2 as large
and not all the time for cruising?
I worry about them shorting but would simplify
things with their use.
How much over the pack voltage do you need to make
up for voltage spikes?
Can you use diode logic to do contactor settings,
combo's reliably using 3 amp diodes?
Can you use then back to back on C coils to reduce
their contact wear?
I'm thinking about one still for the Freedom EV as
a low cost option.
>
> > At full voltage the 2 diodes still in circuit
> could be bypassed
>
> There shouldn't be any diodes in the circuit at full
> voltage -- just
> contacts and batteries.
>
> > While you don't get current multiplication like
> PWM at low motor
> > voltage at 1/4 battery voltage you do have 4
> batteries in parallel
> > so 4 times the current available so the effect is
> similar.
>
> Right. It multiplies current; just not the same way
> as a PWM controller.
> But the consequences are the same (1/4th voltage
> means 4 times the
> current).
>
> > I'd love to hear how a contactor car is driven.
> I.E. When travelling
> > at speed would battery voltage vary between full
> and off or full
> > and half to maintain speed. Accelerating through
> voltage steps and
> > gears.
I just use my pedal as on/off with voltage steps
on switches like trans shifting though for others,
the 3 step pedal would be better as prevents full
power starts which can be exciting ;-)). Not to
mention, breaks stuff.
>
> You've pretty much got it. To drive at a given
> speed, you need a
> particular value of torque. This requires a
> particular motor current,
> which in turn requires a particular motor voltage.
>
> With a contactor controller, you can only set the
> motor voltage in
> discrete steps. If you want something in between,
> then you have to cycle
> back and forth between steps. For instance, if 55
> mph requires 55v, and
> your contactor controller only provides 24v, 48v, or
> 96v, then you cycle
> back and forth between 48v and 96v steps.
1/4-1/2 Field weakening is good for these
inbetween steps so less cycling is needed. This allows
speed changes without the ineff of full field
weakening so keep it as low as you can and get the
desrired effect.
>
> With a PM motor (Lynch, Lemco, Etek, etc.), you'd
> get rather abrupt
> lurches in speed as you switched voltages. This is
> because a PM motor
> fights to run at exactly the speed commanded by the
> voltage. A 2:1
> voltage change can cause a 100:1 current change, and
> this causes drastic
> changes in torque. It would be like driving a normal
> ICE car where you
> could only operate the gas pedal as an on/off switch
> -- drastic
> accelleration followed by drastic engine braking.
Not to mention can melt the commutator like happened
to my E-tek!!! And that was on 36vdc and a resistor in
series!!!
Yet no problem with a series motor rated at 1/2 the
E-tek's power at the same voltage!!
>
> But with a series motor, the steps are quite
> gradual. A 2:1 voltage
> change only produces about a 2:1 torque change. This
> is only enough to
> cause mild accelleration and mild decelleration.
> Thus with a series
> motor, you only need to switch the voltage up/down a
> few times a minute.
Series really is the way to go for so many reasons.
Thanks,
Jerry Dycus
> --
> "The two most common elements in the universe
> are hydrogen and stupidity." -- Harlan Ellison
> --
> Lee A. Hart 814 8th Ave N Sartell MN 56377
> leeahart_at_earthlink.net
>
>
__________________________________________________
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--- End Message ---
--- Begin Message ---
Given all the differences in motors available and the ever growing field of
controllers available I have a very simple question which I hope gathers
several different answers for consideration....
Within reasonable monetary expenses (less than $5K) what are some good
alternatives for motor/controller combinations that would produce average
"get up and go" as well as good efficiency for distance?
Some specs...
Motor should be in the 8 - 9 inch diameter range but a larger motor with
good specs could be considered.
Batts would be in the 144 to 192 volt range with 40 to 65 ah (probably
Intimidators at 55 ah and 45 lbs.)
Glider would be VW Cabriolet or like size.
Could you include some web links with answers.
Thanks
Jeff "newbie" need-to-get-my-grin-on Wilson
--- End Message ---
--- Begin Message ---
I saw them for sale on a website. I know they'll need forced air cooling which
I planned on taking advantage of but other than that are they truely clones of
the Etek even though they nameplate at 36 volts?
I also saw that alot of people overvoltage eteks. Is that safe to do on long
term as long as you keep the motor amps down and the heat down or is it just
for racing?
Thanks,
Mark Hastings
[EMAIL PROTECTED] wrote:
Given all the differences in motors available and the ever growing field of
controllers available I have a very simple question which I hope gathers
several different answers for consideration....
Within reasonable monetary expenses (less than $5K) what are some good
alternatives for motor/controller combinations that would produce average
"get up and go" as well as good efficiency for distance?
Some specs...
Motor should be in the 8 - 9 inch diameter range but a larger motor with
good specs could be considered.
Batts would be in the 144 to 192 volt range with 40 to 65 ah (probably
Intimidators at 55 ah and 45 lbs.)
Glider would be VW Cabriolet or like size.
Could you include some web links with answers.
Thanks
Jeff "newbie" need-to-get-my-grin-on Wilson
--- End Message ---
--- Begin Message ---
It looks like they are using the half shafts as one of
the suspension links like the old corvette system. So
the camber and toe in would be adjusted with the lower
links. It's not a system I would feel comfortable at
high speed with gobs of power. If you should break a
half shaft, that wheel will do whatever it wants.
These systems have worked well in vehicles were you
have known amounts of power, but are not pretty when
they fail.
Gadget
--- Joe Smalley <[EMAIL PROTECTED]> wrote:
> I looked at the photos and wonder how the camber is
> controlled. There were
> no photos of the bottom of the shock. Is it being
> used as a strut to control
> the camber?
>
> It is very important to make sure all the lateral
> struts (including the half
> shafts) are parallel and the same length to control
> the geometry. If they
> are not, the camber will change as the wheel moves
> up and down relative to
> the frame, or the half shaft will bind. There are
> some ways the designer can
> get around these limitations but just putting a
> motor outboard of the brake
> and moving the inner U-joint a few inches outboard
> will make it bind. The
> inner suspension pivots must be moved to compensate.
>
> Joe Smalley
> Rural Kitsap County WA
> Fiesta 48 volts
> NEDRA 48 volt street conversion record holder
> [EMAIL PROTECTED]
>
> ----- Original Message -----
> From: "Christopher Robison" <[EMAIL PROTECTED]>
> To: <[email protected]>
> Sent: Wednesday, April 27, 2005 9:51 PM
> Subject: Re: IRS Replacement
>
>
> > Probably not the answer you were looking for, but
> I just had to share
> > this... I have seen a few IRS setups you can buy
> and retrofit into your
> > car, but this is by far the most gorgeous one I've
> come across, made by
> > Wayland's friends at Dutchman Motorsports (from
> whom I'll be buying much
> > of my driveline, as it turns out -- thanks for the
> tip, John!!):
> >
> > http://www.dutchmanms.com/1_irsnav.html
> >
> > If you were wanting to build something, you might
> take some inspiration
> > from how this is designed. Note the inboard brakes
> (maybe more obvious
> > from the side view), making the wheels very
> lightweight. This would be
> > critical if you were going to use wheel motors.
> You'd want a design very
> > much like this, but instead of the differential in
> the center, you'd have
> > the brakes there, very close together but not
> connected to each other.
> > Just outside of the brakes you'd have your wheel
> motors. All of this would
> > be mounted to the frame. Then you'd have your
> half-shafts going to the
> > wheels. Dutchman sells the wheel hub carriers and
> half shafts separately,
> > and I figure they'd probably be willing to work a
> deal with you, if you
> > just wanted to buy the brakes, support arms and
> other framework stuff.
> > It'd be up to you to design the center structure
> (motor-brake-brake-motor)
> > such that the mounting points would be compatible.
> >
> > Dunno ... just a thought. For what it's worth, I
> think this would be
> > *really* cool.
> >
> > --chris
> >
> >
> >
> > Bill Dennis said:
> > > Is there some place on the web I can read about
> how to replace the
> > > Independent Rear Suspension on a car to have
> wheel motors (or hydraulic
> > > motors, as Lee Hart recently suggested)? Rear
> suspension on the car is
> > > currently just the simple old: Strut, Control
> Arm, Suspension Arm and
> > > Suspension Knuckle.
> > >
> > > Thanks.
> > >
> > > Bill Dennis
> > >
> > >
> >
>
>
visit my website at www.reverendgadget.com
--- End Message ---
--- Begin Message ---
Ryan Stotts wrote:
> Isn't there some devious way to construct an all or nothing type
> inverter? And cheaply?
Yes. As has been pointed out, it's a commutator! It was invented for us
over 100 years ago, and has been thoroughly perfected for you.
Quin Pendragon wrote:
> OK, here's a crazy idea - how about an AC motor with attached
> commutator?
That is exactly what a normal DC brushed motor is! An AC motor with a
mechanical switch for an inverter.
Rod Hower wrote:
> It's not possible! All of the current must go through the
> semiconductor switches that create a sinusoidal waveform from
> the DC battery pack.
If you don't want semiconductors, then the commutator (mechanical
switch) is your only practical choice. The other alternatives are worse.
For instance, the homopolar motor, which has slip rings instead of
brushes but requires a few volts at tens of thousands of amps. Or you
can use ignitrons (vacuum tube equivalents to transistors), but you'd
need a 1000+volt pack. Or a rotary converter with a flywheel for energy
storage.
Another alternative is to do it with semiconductors, but get rid of all
the complexity and finesse that usually comes with AC inverters. The
cheapest power semiconductor (most watts per dollar) is the SCR. Use
them to build a simple 6-step 3-phase inverter.
Nick Viera wrote:
> what if you built a hybrid AC/DC drive system EV? Hybrid in the
> sense that you have two motors and controllers -- one smaller AC
> motor + inverter and one smaller Series DC motor + PWM controller
This makes some sense. Use an AC drive that is optimized for low-speed
and low-power operation. It produces just barely enough power for normal
cruising, and it is optimized for efficiency and range. It also provide
mild regen capabilities.
Then add a big series motor and contactor controller. It provides the
brute force, neck-snapping, tire-burning accelleration.
By coordinating the two drives, you get the best features of both!
--
"Never doubt that the work of a small group of thoughtful, committed
citizens can change the world. Indeed, it's the only thing that ever
has!" -- Margaret Mead
--
Lee A. Hart 814 8th Ave N Sartell MN 56377 leeahart_at_earthlink.net
--- End Message ---
--- Begin Message ---
Mark Hastings wrote:
I saw them for sale on a website. I know they'll need forced air cooling which
I planned on taking advantage of but other than that are they truely clones of
the Etek even though they nameplate at 36 volts?
I also saw that alot of people overvoltage eteks. Is that safe to do on long
term as long as you keep the motor amps down and the heat down or is it just
for racing?
Thanks,
Mark Hastings
I suppose you can call them Eteks - the one I bought from EVparts also
says 36V, made in China. It looks similar to the ones offered on eBay a
while ago with integrated adapter for a cooling pipe, no mention of Etek
or B&S anywhere. I think there are manufacturers in China who have just
copied the design and sell them a bit cheaper than the "original"...
As for overvolting, if the motor is well balanced it can be revved
higher than nominal rpm. But with these low priced motors, there is
naturally no guarantee that they last if taken much higher than what the
manufacturer suggests.
Another thing is that the supposedly well built PermMotor PM 132 that I
have is not too well balanced and it vibrates with 24 V. It is nominal
72V, i.e. 3240 rpm... well. At least it is not as loud as the a.m
Etek-version.
Pekka
--- End Message ---
