EV Digest 5025
Topics covered in this issue include:
1) Re: Loading wrong frequency (was RPM matching)
by Lee Hart <[EMAIL PROTECTED]>
2) Re: Contactor identification, potbox without a pot?
by Lee Hart <[EMAIL PROTECTED]>
3) Electric car for sale -- immediate bids invited by December 30
by "Lewis Weiss" <[EMAIL PROTECTED]>
4) Re: potbox without a pot
by Ryan Bohm <[EMAIL PROTECTED]>
5) Re: Electric RCs are taken seriously
by Aaron NMLUG-EV <[EMAIL PROTECTED]>
6) Re: Loading wrong frequency (was RPM matching) Comments
by "Bob Rice" <[EMAIL PROTECTED]>
7) Charging batteries
by paul wiley <[EMAIL PROTECTED]>
8) Re: Charging batteries
by "David Roden" <[EMAIL PROTECTED]>
9) RE: Clutchless shift with rpm-matching?
by Cor van de Water <[EMAIL PROTECTED]>
10) Festiva or Metro
by [EMAIL PROTECTED]
11) Re: Loading wrong frequency (was RPM matching)
by Victor Tikhonov <[EMAIL PROTECTED]>
12) Re: Loading wrong frequency (was RPM matching)
by Victor Tikhonov <[EMAIL PROTECTED]>
13) RE: Festiva or Metro
by "Roger Stockton" <[EMAIL PROTECTED]>
14) Re: Festiva or Metro
by Andrew Letton <[EMAIL PROTECTED]>
15) Re: potbox without a pot?
by James Massey <[EMAIL PROTECTED]>
16) RE: Festiva or Metro
by "Don Cameron" <[EMAIL PROTECTED]>
17) Re: gathering info about AC conversion
by Electro Automotive <[EMAIL PROTECTED]>
18) RE: Festiva or Metro
by Bob Bath <[EMAIL PROTECTED]>
19) RE: Festiva or Metro
by "David Roden (Akron OH USA)" <[EMAIL PROTECTED]>
--- Begin Message ---
Victor Tikhonov wrote:
> Lee wrote that loading in wrong frequency and banging it in in right next
> CPU cycle will effectively stall an AC motor (synchronous is discussed).
> I want to understand this better, as I haven't experimented with this
> first hand, and hopefully Lee, you can elaborate.
Driving a synchronous motor is like pedalling a tricycle (pedals directly
connected to the wheel; no gears or one-way ratchets). If you press on the
pedals at the right times, you go forward. At a different time, you go
backward. Pedal at the wrong times, and you go NOWHERE! You just rock back
and forth in place.
With a synchronous motor, it is the PHASE that matters; not the frequency. To
continue the pedal analogy, if you step on a pedal just after it passes top
dead center, you create positive torque that tries to speed you up and move
you forward. If you step on a pedal just before top dead center, you create
negative torque that tries to slow you down, or can even push you backwards.
> I think all depends on how you define "wrong" frequency. If I'm running
> the motor at 300 Hz and banging 301 Hz to it (technically, "wrong"
> frequency, but by 0.3% only), I don't see why the motor will stall.
At the instant you change frequency, nothing actually happens. The motor can
only tell that the frequency has changed a short time later, by noticing that
the phase is changing. For example, the next zero crossing will arrive early.
The motor tries to speed up so the zero-crossings of its back emf match the
zero-crossings of the applied voltage. Can it do so? That depends on a) how
fast the frequency is changing, and b) how much inertial load is on the
motor.
Let's consider the phase angle between the stator's rotating magnetic field
(created by the AC voltage applied to its windings), and the rotating
magnetic field from the permanent magnets in the rotor. At zero torque (no
load on the motor), this angle is 0 degrees. At peak torque, this angle is 90
degrees. At lighter loads, it will be some angle between 0 and 90. If the
phase angle is less than 0 deg, the motor is acting as a generator; its
torque is negative and it is pushing power back into the supply. At angles
greater than 90 deg, the torque is falling off (and reaches zero torque again
at 180 deg).
When you change the frequency, this phase angle starts increasing. Suppose the
rotor was running at half-torque; about 30 degrees since sin(30)=0.5. After 1
revolution at the new frequency, the rotor is 1.2 degree behind.
Sin(31.2)=0.518, so the torque increased about 3.6%. This tries to speed up
the rotor; to catch up with the new applied frequency. If this small torque
increase is enough, all is well; the motor leaps ahead to the new speed.
But suppose the load on the motor is very heavy, with lots of inertia (like a
1-ton car). In one revolution (1/300th of a second at 300hz), the speed can't
measurably change at all. So for another rotation, the rotor and stator
frequencies are still off, 301hz vs 300hz. The phase error increases with
each revolution; 1.2 deg. after 1 rev, 2.4 deg. after 2, 12 degrees after 10
revolutions, etc. As the angle gets larger, sin(angle) gets larger, too. The
motor is producing more torque as the rotor falls farther behind.
Again, if the torque can get high enough fast enough, all is well. The rotor
will lag back a bit more, but eventually catch up. A mechanical analogy would
be if you're pulling a wagon with a rubber band. When you start pulling
quickly, the wagon takes a while to start moving; the rubber band stretches.
But as long as you don't stretch the rubber band to the breaking point, the
wagon eventually starts moving and catches up.
But what if the frequency changes too much, too fast? We started at 30 deg.
and can't go past 90 deg; so the rotor can't lag behind by more than 60 deg
or our magnetic "rubber band" will break! At 1.2 deg/revolution, it only
takes 60/1.2 = 50 revolutions of the motor after the frequency change before
the rotor is a full 90 degrees behind the stator. 50 revolutions / 300 hz =
0.0166 seconds.
Once the rotor lags by more than 90 degrees, things get bad fast. The torque
is actually *falling* as you go past 90 degrees, so instead of speeding up,
the rotor will slow down. This makes the phase angle lag even greater,
causing further reductions in torque. Eventually, it reaches 180 deg, and the
rotor begins acting as a generator, and slows the load down! The phase keeps
right on increasing, from 180-360 degrees which is back to zero.
What you would observe when this happens is that the motor suddenly begins to
vibrate violently, rapidly pulsating forward/backward/forward/backward. It's
average torque per revolution falls to almost zero. The inverter had better
have some very good current limiting, or it will be destroyed by the current
and voltage transients.
This phenomenon is all too familiar to anyone who has tried to build a stepper
motor controller. Steppers are in fact PM synchronous AC motors. You can only
change the step rate (frequency) up/down at a certain rate, or they will lose
their position, and the effect is strongly dependent upon mechanical loading.
With a high-inertia load, the motor can become unusable. The "spring" action
of the magnetic field combines with the mass of the rotational inertia to
form a mechanically resonant system; it oscillates!
> So the question is, will it stall at 1% frequency difference?
Yes, it CAN stall, even with a 1% frequency change, if the mass is large and
the motor was already near maximum torque (near 90 deg phase angle).
--
Lee A. Hart 814 8th Ave N Sartell MN 56377 [EMAIL PROTECTED]
--- End Message ---
--- Begin Message ---
James Massey wrote:
> The other thing I found and did a double-take when I took the cover off
> it is the potbox. Well... The traction cable lays across the top of it
> and a magnet is on the arm inside. There is an electrical component
> (2-wire) in between the cable and the magnet. The magnet moves away
> from the cable, and switches on the outside select forward/reverse
> (double-acting potbox). Anyone know what this is?
Could be several things. It could be hall effect IC, in which case there will
be a DC voltage on the two wires, and it draws a variable current depending
on the strength of the magnetic field (i.e. how close the magnet is).
It could be a simple coil with an iron core, and the magnet biases its
magnetic field. In this case, there would be an AC signal on the two wires,
and the frequency or duty cycle changes depending on the magnet's proximity.
Other possibilities are a GMR (Giant Magneto Resistive sensor), a Rogowski
coil, magneto-optical detectors, Wiegand wires, or several reed switches that
select resistors in a stepwise fashion, or a strain gauge with an iron
armature that bends it from the magnetic field, etc.
--
Lee A. Hart 814 8th Ave N Sartell MN 56377 [EMAIL PROTECTED]
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--- Begin Message ---
Electric car for sale -- immediate bids invited by December 30
===================================================
Dear EV Enthusiasts,
Here is info on our Electricar for sale. Visit http://www.lewisweiss.com to
see detailed info and photos.
We will entertain the best bid up to December 30.
Please spread the word.
Thanks much.
Lewis Weiss
direct line: 828 264 3623
[EMAIL PROTECTED]
------------------------------------------------------------------------
FOR SALE: 1995 US Electricar
Color: Brown
Location: Boone, North Carolina
Base Vehicle: 1995 Geo Prizm
VIN # 1Y1SK5267SZ023206
Motor: 3-phase 50,000-watt motor controlled by 50 KW Hughes Dolphin controller
Drivetrain: Transmission is locked into 2nd gear, as appropriate for an
electric car.
Controller: Hughes 50 KW AC Dolphin Vector control (the controller currently
installed does not work, but we are willing to also provide an extra controller
which also does not work in order to help provide parts which might complete a
working controller).
Batteries: 50 Hawker Genesis absorbed glass mat (AGM) 26 AH battery modules
under floor in 2 parallel strings of 25 each, for 300 volts and 52 amp-hours.
Battery pack weight 1150 pounds.
The battery under the hood that runs the Accessories will need to be replaced.
System voltage: 300 volts
Charger: On-board Dolphin for 110/220 volts built-in
Heater: Hot water-based heater, 2 KW
DC/DC Converter: Dolphin DC-DC, 1 KW
Instrumentation: E-meter, telemetry from controller
Top speed: 81 MPH (according to test data; our car is not currently working)
Acceleration: Fast as a normal car (according to test data; our car is not
currently working)
Range: 30-45 miles
Seating capacity: 5 adults, full trunk access (batteries are under car, not
in trunk)
This vehicle is very similar to the car purchased in January, 2001 by Jon
Mauney and driven daily by him.
This Geo Prizm US Electricar, when working, is quite quick, drives like a nice
solid Ford Taurus, and with the battery weight underneath the car, it is
extremely stable. Also, since there are no batteries in the passenger
compartment or in the trunk, it has just as much space as a regular Geo
Prizm/Toyota Corolla.
This car is being sold by a non-profit organization that wanted a non-polluting
vehicle to drive short distances in the mountains of North Carolina. It was
purchased in March, 2001 from the State of Oregon, trucked to North Carolina,
but it has never been driven since then, as we got it with the wrong batteries
installed.
The Hawker Genesis absorbed glass mat (AGM) batteries which are being provided
with this car were installed in a different car and used for only 3-4 months
for a short 1-mile trip once a day. Due to no technician being available, they
were never installed in this car, and therefore they are still in good charge
condition. These batteries were tested about 2 months ago and they were
determined to be working fine and holding a good charge. These batteries could
be useful installed in other electric cars as well.
The body and interior are in excellent shape. The car is being sold as-is.
Although this is an excellent car for an electric car enthusiast to enjoy a
real state-of-the-art electric car, it will require some trouble-shooting to
get this car running again. Also, we understand that this car is a prime
candidate to be convered over to a DC system, because it has the brake system,
heating system etc. already set-up and approved.
The car will be supplied with the 50 Hawker Genesis absorbed glass mat (AGM)
battery assembly in holder, the 2 (two) Hughes 50 KW AC Dolphin Vector
controllers as well as an extra water pump motor and water pump housing, as the
water pump with the car may not work, and a separate charger power supply
board. These parts (batteries, 2 controllers, water pump motor, water pump
housing, power supply board) will be provided along with the Geo Prizm itself,
but not installed, so that the purchaser can determine the working condition of
these parts.
Also, there is a LOT of valuable written documentation that will be supplied
with this car, including US Electricar Technical Training Course documentation,
circuit diagrams and manual documentation not easily available elsewhere.
All interested parties are invited to investigate this car, and to make an
offer for the purchase of the complete package before December 31, 2005. For
more information please call Lewis Weiss at 828 264 3623 or email [EMAIL
PROTECTED]
--- End Message ---
--- Begin Message ---
Hi all,
James said:
The other thing I found and did a double-take when I took the cover
off it is the potbox. Well...um, can you call it that when it doesn't
have a pot? The traction cable lays across the top of it and a magnet
is on the arm inside. There is an electrical component (2-wire) in
between the cable and the magnet. The magnet moves away from the
cable, and switches on the outside select forward/reverse
(double-acting potbox). Anyone know what this is?
Someone might have already answered this (I'm on digest), but I'd
venture to guess this is a Hall-effect throttle unit. My conclusion
from using both a pot and a Hall-effect assembly is that the latter is
superior. Since it's not a physical connection, it won't wear out.
Dirt and dust won't affect it. The performance won't degrade over
time. And in the case of unit with the sensor embedded in the pedal
assembly (like the one sold with Zillas), you don't have to worry about
the throttle cable. When I first installed a potbox, it was a pain to
arrange everything around the physical cable. Running an electrical
cable in the case of the Hall-effect pedal assembly was a piece of cake.
-Ryan
--
- EV Source <http://www.evsource.com> -
Free Shipping on *all* items in our store for December!
Includes Zilla, PFC Chargers, and WarP Motors
E-mail: mailto:[EMAIL PROTECTED]
Toll-free: 1-877-215-6781
--- End Message ---
--- Begin Message ---
On Fri, 2005-12-23 at 03:45, Philippe Borges wrote:
> Purchase single cells !
>
> 3.7V4Ah lipoly capable of 10C continuous are actually at 20$
> so make your 160$ own pack
My RC planes are all in the 4oz to 2lb range. (around 150g to 750g)
Mostly "park flyers".
LiPoly packs for these tend to run in the $15-$45 range.
350mAh to about 1.8Ah, 2-3 cell series packs.
There are many little brushless motors out there,
costing $30-$80 (add a $50 controller)
weighing less than an ounce (say 25g) which produce
10-11oz (300g) thrust at around 7A, perhaps 35-45W.
Around 2-3x the cost of simpler brushed motors,
but well worth it IMOHO.
I'm not tempted to get into larger, more expensive
airframes and battery packs.
--
Aaron Birenboim \ I have an inferiority complex,
Albuquerque, NM, USA \ but its not a very good one.
aaron at birenboim.com \
http://aaron.birenboim.com \
--- End Message ---
--- Begin Message ---
----- Original Message -----
From: "Lee Hart" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Sunday, December 25, 2005 11:03 PM
Subject: Re: Loading wrong frequency (was RPM matching)
Hi All;
Snip a bit
> Victor Tikhonov wrote:
> > Lee wrote that loading in wrong frequency and banging it in in right
next
>
Hi All;
Lee gives a great explanation above on AC motors. As applied to RR
locomotives, all the above is very noticable running the AC and DC lokies. A
DC engine will give you glassy, silky, movement right off the line, one of
those " Oh we're moving" type of starts that us train drivers strive to
do.AC ? Well, it's a crapshoot as to a smooth start.You almost always get a
bit of the above "Cogging"or a BAM at start. Sometimes spinning the wheels a
bit. Other times under severe load, like trying to drag two cars away from a
bridge with their brakes on, it just sits there and hums like hell!A DC
machine woulda just pulled those cars away, as I had hoped, so we could
reconnect the brake pipes clear of the no- foot- walk bridge and the abis,
in the dark. Emded up shinnying out there to reconnect everything
anyhow.Never ran any AC Diesel lokies to have any reports on. All Amtrak's
are DC drive with gobs of off the line torque. Trains, the AC designers were
betting on, the trains sheer mass, to smooth away the cogging effect.
I have been lucky to have driven the EV-1 and was blown away by the
beautiful, smooth power. The GM Guyz did ALL their homework on this
one!Well,whatdoyaexpect, some of the best auto guys on the planet did this
one! Move it two inches or blast down the strip, full bore! You are in
command! Smooth, cool, gear sounds, and just LOVE that regen! Ah! Regen,
that's why we go through the hassle and expense of AC, anyhow.Well, no
brushes is nice, too.
Would be fun to see a White Zombie , vs T Zero shootout! Ha Ha!
EVerybody is direct drive, even playing field.IF there was still an EV
Project at GM, A EV-2 in the lineup, too.Had GM spent the money they did
FIGHTING thre EV laws in CA we would be running against and cheering them
on. Gees! In my Perfect World there would be a GM EV racing team out there
kicking ass, BIG time. Traveling about the USA with their Hybrid semi
carrying the latest in EV Racing iron. EVen Dennis would have his hands full
running these guyz. But they would have deeper pockets,than any of us, and
that's sure what you need to race anything.
Battery Beach Burnout is coming up, less than a month.!
Seeya there!
Bob
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--- Begin Message ---
Just a quick question before i order a charger. Is it better to charge AGM
batts in series (i have 48 volts) or with 4, 12 volt chargers?
Thanks,
Paul
---------------------------------
Yahoo! for Good - Make a difference this year.
--- End Message ---
--- Begin Message ---
On 26 Dec 2005 at 10:25, paul wiley wrote:
> Just a quick question before i order a charger. Is it better to charge AGM
> batts in series (i have 48 volts) or with 4, 12 volt chargers?
A much debated topic here, some years back.
The danger of "modular charging" (multiple 12v chargers) is that the chance
of failure is 4 times the chance with a sirngle series charger, and if one
charger fails its battery is likely to be reversed (damaged or destroyed)
the next time you use the EV. Also, modular chargers usually weigh more and
may cost more (or less ;-). Finally, EV batteries usually need high power
charging for utility and lifespan reasons, and this is more common in large
high voltage chargers than in small 12 volt ones.
The advantage is that the battery pack is more evenly charged. The closer
to the cell level you charge, the better balanced the battery remains.
If you get reasonably high power chargers (C/10 to C/5) and have some means
of confirming that all batteries are actually charged before using the EV, I
think the potential problems with modular charging are minimized and it's
preferable. Others may have different views and I'm sure you'll hear from
them!
David Roden - Akron, Ohio, USA
EV List Assistant Administrator
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--- Begin Message ---
I do not understand why everyone is so fixed on frequency control,
as to my opinion there is only one parameter that is of importance
to a smooth AC motor control: phase.
The frequency is a resultant from applying a certain phase (-difference)
over a certain time.
Acc pedal only needs to drive a certain phase setting for the motor,
when its fully depressed you want to achieve close to 90 deg phase
advancement for a max torque, when the acc pedal is fully released
you may want a little negative phase for braking, when the brake is
lightly engaged you go up to 90 deg negative in phase.
The same holds for the RPM control for clutchless shift:
- determine the frequency difference
- apply a phase shift until the frequencies match
You cannot force a frequency on an AC motor, the RPMs are the
result of the electrical and mechanical forces.
(Lee Hart already explained that a frequency step of even 1 Hz can
lead to almost ZERO torque when you cross the 90 deg PHASE point)
You can measure the RPM and drive the motor to achieve the RPM
that you want and the phase difference you apply determines how fast,
given the other parameters such as inertia and frequency difference.
Hope this helps,
Cor van de Water
Systems Architect
Email: [EMAIL PROTECTED] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [EMAIL PROTECTED]
Tel: +1 408 542 5225 VoIP: +31 20 3987567 FWD# 25925
Fax: +1 408 731 3675 eFAX: +31-87-784-1130
Proxim Wireless Networks eFAX: +1-501-641-8576
Take your network further http://www.proxim.com
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Arthur W. Matteson
Sent: Tuesday, December 20, 2005 2:46 PM
To: [email protected]
Subject: Re: Clutchless shift with rpm-matching?
On Mon, 2005-12-19 at 09:03 +0200, Osmo Sarin wrote:
> To help to shift on the fly: when the clutch pedal (without a clutch)
> or a hand switch is pressed, or gear is shifted to neutral, the
> controller would ignore the acc pedal signal and set motor rpm to same
> as gearbox rpm. Maybe the speedometer sensor signal could be used to
> give the gearbox rpm?
A speedometer reading would be a useful thing for an EV controller. I
was going to add a tachometer and "shift-suggester" to my Renault, or at
least had the idea in the works. The controller would learn the
efficiency of the system at different speeds and suggest when it would
be a good time to shift up or down with a small arrow, in order to best
use the energy in the batteries. The current gear would have a box
around it on the screen, as well. This idea of course requires
knowledge of the motor RPM which is provided by two 90-degree
out-of-phase optosensors in my case (I use sensored field-oriented
control for my AC system).
> Would it be very complicated construction? Easier in AC or DC system?
The construction would be simple, but the implementation challenging.
Many AC drives already have FOC, so adding this would be complicating
things by 25-50% more. Integral control wouldn't be appropriate because
it's mainly useful for setting the speed closely over a long period of
time. A mix of proportional and differential control would be best
because of the small reaction time. It isn't critical that the speeds
are exactly equal, but it needs to get within 10% quite quickly.
Basically the only way to do this for a DC motor is to have RPM
feedback. An AC motor would be somewhat more predictable because you
can directly control the speed by changing the input frequency, but
without FOC it would still be sloppy. Driving an AC car with a V/Hz
control is quite a trip, anyway - not something you'd want to invest in
for the long run!
As suggested, I built my Renault's AC electronics and software
completely from scratch. The car has a moderately-well-working FOC but
much still needs to be done. By changing the rotor time constant I saw
much varied performance and response, as well as the loop constants.
Tuning your (future?) system correctly to work in all gear transitions,
Osmo, would be the brunt of the work. You might find that some constant
settings would work well in some gears but much worse in others. Of
course, anything can be fixed in software, and a small table-lookup of
constants would allow you to tune the constants separately for each
gear!
The issue with the DC motor is that it only has one independent
variable: torque. The slope of current is a function of the voltage you
give it and the speed it's going. Increasing the voltage simply
increases the slope of current...and as the motor speeds up this factor
then cancels back out.
Let me explain myself. Without any feedback, we can compare the
necessary waveforms to increase the speed of an AC/DC motor:
- Provided your open-loop AC motor has sufficient torque to do so
(which it most likely does), the velocity input to your cosines -
cos(w*t), cos(w*t+pi/3), cos(w*t+2*pi/3) - will merely be a unit step
scaled to the appropriate size. This step will be the same no matter if
you have a big or small motor. Your voltage will scale accordingly,
simply being multiplied by the *applied* velocity. This sudden change
in commanded velocity will not hurt the motor, and it will not draw
infinite current because of its limited size. Mathematically this
frequency change is simple and could technically be done with the
throttle, with a setup like the one I had on June 6, 2004.
- A DC motor has a somewhat more complex relationship between current
input and speed, since torque is reasonably proportional to current.
Without a closed loop, the current waveform you have to give it - or
duty cycle as the case may be - is dependent on its inertia, its extra
loads (such as a pump), and its own electrical characteristics. Much
like force equals mass times acceleration and velocity equals
acceleration times time for straight-moving objects, you need to
integrate the sum of your torques to get your speed. Working backwards
to get torque, we find that we need to apply a unit impulse of current
to get the motor to come to the right speed! Infinite current is
impossible to provide, and the unit impulse needs to be "rectangulated"
based on the situation's characteristics in order to provide decent
acceleration. In contrast, the AC motor will respond to a speed change
without the unit step function being slope-limited at all, even though
doing so may speed up the response.
My conclusion is that I believe the AC motor would be easier to adjust
without a closed-loop, but this is somewhat irrelevant since the only
good implementation would be closed-loop for both motor types.
Preferably this system would be in software; it would be more reliable
and easier to tune in this way.
I hope this answers your question, Osmo.
- Arthur
http://mywebpages.comcast.net/awmatt
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--- Begin Message ---
If you were converting a "small car" today, would you rather used a late
model Ford Festiva or Geo Metro. I looked at both cars earlier today and I
believe the Festiva to be a superior conversion candidate. But, I am
interested in
what others have to say, and why other people aren't choosing the Festiva.
In my opinion, advantages of the Festiva:
There is at least 2.75" more length to fit a motor which opens up a lot more
options than the 8" ADC.
- You could even easily fit a Warp 9" for some serious performance.
Battery mounting appears to be easier, especially if you take out the rear
seat, which is very easy
Currently, you may be able to get a donor car pretty inexpensively
In my opinion, disadvantages of the Festiva:
No off the shelf kit, as far as I know
Few examples to work from
Parts availability - 5 years from now - is questionable
The cars are generally older and more difficult to find in low mileage
Stock brakes seem a little small - from what I could tell from the
disassembled car
I would like to know what others think, and why they decided to go with the
Metro rather than the Festiva. I think the Festiva with the 9" motor and 14 x
12 V AGM batteries and a 1k Zilla controller locked in 2nd gear would make a
great car. I think better than a comparable Metro which would be limited to a
8" ADC and 12 x 12 V batteries (I've heard space issues). Anyone need to
correct me?
--- End Message ---
--- Begin Message ---
Thanks Lee, you didn't have to go so much in depth of
basics, but I guess it woo benefir many on the list.
Lee Hart wrote:
So the question is, will it stall at 1% frequency difference?
Yes, it CAN stall, even with a 1% frequency change, if the mass is large and
the motor was already near maximum torque (near 90 deg phase angle).
Effect of going "out of phase" can be easily demonstrated by
unplugging starting capacitor of single phase appliance AC motors:
it will hum but not move - if you spin it in any direction,
it will pick up the speed and rotate, but with little
torque, you may be able to "stall" it by hand.
The question was about particular circumstances where you totally unload
3 phase the motor in order to shift, so no load. Phase margin
is wide enough (has to be tested though) and inverter power is
sufficient to slow down/lurch it forward rather than stall.
Victor
--- End Message ---
--- Begin Message ---
Thanks Lee, you didn't have to go so much in depth of
basics, but I guess it woo benefit many on the list.
Lee Hart wrote:
So the question is, will it stall at 1% frequency difference?
Yes, it CAN stall, even with a 1% frequency change, if the mass is large and
the motor was already near maximum torque (near 90 deg phase angle).
Effect of going "out of phase" can be easily demonstrated by
unplugging starting capacitor of single phase appliance AC motors:
it will hum but not move - if you spin it in any direction,
it will pick up the speed and rotate, but with little
torque, you may be able to "stall" it by hand.
The question was about particular circumstances where you totally unload
3 phase the motor in order to shift, so no load. Phase margin
is wide enough (has to be tested though) and inverter power is
sufficient to slow down/lurch it forward rather than stall.
Victor
--- End Message ---
--- Begin Message ---
[EMAIL PROTECTED] wrote:
> I think the Festiva with the 9" motor and 14 x 12 V AGM
> batteries and a 1k Zilla controller locked in 2nd gear
> would make a great car. I think better than a comparable
> Metro which would be limited to a 8" ADC and 12 x 12 V
> batteries (I've heard space issues).
> Anyone need to correct me?
Sure. ;^>
Have a look at this Metro conversion by Canadian Electric Vehicles:
<http://www.canev.com/Conversions/Geo/Geo.html>
ADC 9", Auburn MPC 600 controller, and 192V pack of Optima G31s. Tranny
locked in 2nd.
You may still prefer the Festiva, but be aware that the Metro is capable
of accepting the same sort of performance bits that you envision.
In favour of the Metro/Swift might be that you ought to be able to find
parts easier, expecially performance-oriented things like stiffer sway
bars, shocks/springs, heavier duty clutches, etc.
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
OK, I'll take the counterpoint and list some advantages to the Metro:
(FYI, the Metro is designed/built by Suzuki and has existed under
various names since about '85, including Suzuki Swift, Pontiac Firefly,
Chevy Sprint, Geo Metro, Chevy Metro, and has been sold in 2-door and
4-door hatchback as well as 4-door sedan and 2-door convertable models.)
- For the '89-'94 versions, there is a pocket rocket version sold as the
Suzuki Swift GT/GTi which has 14" wheels, disc brakes all around, "sport
suspension", and some aerodynamic/styling add-on bits. There are
performance parts available, including springs, struts, strut tower
braces, anti-roll bars, etc. Very Fun Cars!
- I believe that the 4-cylinder models (some '89+ Swifts as well as some
'95+ Metros) will fit a 9" ADC motor (without tailshaft), but don't take
this as gospel - find and measure one!
- Both Electro Automotive and Canadian EV offer Geo Metro kits and have
experience with many conversions.
- At least in the USA, I believe that there are far more Metro variants
on the road than Festivas, so replacement and salvage-yard parts should
be more available.
- Not sure about the Festiva, but on the Metros, the rear struts are not
located inside the rear coil springs, so it is easy to add air-bag
helpers to the rear suspension. (I can look up the Air-Lift bag p/n if
you need it; I've put them in two different 'zukis.)
- The Suzuki Swift GTi has an (aero drag) CdA of 6.15 ft^2, compared to
the Festiva's of 7.3 ft^2. (Std '92 Geo Metro's is 6.78 ft^2) See:
http://www.mayfco.com/tbls.htm
- I've known Geo's with as many as 20 golf cart batteries. Not
recommended, but doable. (Yes, it uses up the back seat area, but the
back seats are hardly usable in either of these cars anyway, if the
front seat passengers are tall.) 16 is a better number and gives a car
with a pretty solid 60 mile range.
- I think that the limiting factor in either of these cars will be the
transmission/clutch, not the size of motor you can fit between the
tranny and the wheelwell. An 8" ADC motor will kill either of these
transmissions and smoke their clutches, given enough amps.
Hope that helps your decision; let me know if you have any specific
Suzuki (variant) questions.
cheers,
Andrew (...with close to half a million (mostly ICE) miles in 'Zuki
variants.)
[EMAIL PROTECTED] wrote:
If you were converting a "small car" today, would you rather used a late
model Ford Festiva or Geo Metro. I looked at both cars earlier today and I
believe the Festiva to be a superior conversion candidate. But, I am interested in
what others have to say, and why other people aren't choosing the Festiva.
In my opinion, advantages of the Festiva:
There is at least 2.75" more length to fit a motor which opens up a lot more
options than the 8" ADC.
- You could even easily fit a Warp 9" for some serious performance.
Battery mounting appears to be easier, especially if you take out the rear
seat, which is very easy
Currently, you may be able to get a donor car pretty inexpensively
In my opinion, disadvantages of the Festiva:
No off the shelf kit, as far as I know
Few examples to work from
Parts availability - 5 years from now - is questionable
The cars are generally older and more difficult to find in low mileage
Stock brakes seem a little small - from what I could tell from the
disassembled car
I would like to know what others think, and why they decided to go with the
Metro rather than the Festiva. I think the Festiva with the 9" motor and 14 x
12 V AGM batteries and a 1k Zilla controller locked in 2nd gear would make a
great car. I think better than a comparable Metro which would be limited to a
8" ADC and 12 x 12 V batteries (I've heard space issues). Anyone need to
correct me?
--- End Message ---
--- Begin Message ---
At 11:20 PM 25/12/05 -0500, Lee Hart wrote:
James Massey wrote:
> The other thing I found and did a double-take when I took the cover off
> it is the potbox. Well... The traction cable lays across the top of it
> and a magnet is on the arm inside. There is an electrical component
> (2-wire) in between the cable and the magnet. The magnet moves away
> from the cable, and switches on the outside select forward/reverse
> (double-acting potbox). Anyone know what this is?
<snip> It could be a simple coil with an iron core, and the magnet biases its
magnetic field. In this case, there would be an AC signal on the two wires,
and the frequency or duty cycle changes depending on the magnet's proximity.
Hi Lee - and all
It measures 4.5 ohms, and when I 'jit' the throttle arm back and forward it
affects the reading as I'd expect from an inductor in a magnetic field (I
should have measured it before posting yesterday). So there is an [aparent]
inductor sitting in a pair of magnetic fields, one for the throttle
request, the other from the traction cable as feedback.
Now one of the things that Lansing Bagnall did is to build up the control
circuit of their SCR controllers with a bunch of plug-in modules -
multivibrator, pulse selector, pulse shaper, trigger circuit, con. hold
circuit. Each in their own module, a little bigger than a matchbox,
plugging into a set of sockets. But there is another anonymous module,
unfortunately I already stripped off the loom before discovering that
intriguing throttle sensor (so I don't know where the wires went), although
it was at the other end of the assembly to the throttle and the other modules.
Does this provide more clues to how this worked?
Doesn't matter if not, since I'm not going to use it as it is anyway, but
it is interesting to know.
Regards
James
--- End Message ---
--- Begin Message ---
Nothing wrong with blazing a new trail. My New Beetle EV is only one of
three in the world.
What is nice about the Metro is that there is a lot more expertise available
if you want parts or advice. Before I did the New Beetle conversion, I
purchased a 96 Metro, and it has enough room to accommodate a 9" ADC motor.
good luck.
Don
Victoria, BC, Canada
See the New Beetle EV Conversion Web Site at
www.cameronsoftware.com/ev/
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of [EMAIL PROTECTED]
Sent: December 26, 2005 1:36 PM
To: [email protected]
Subject: Festiva or Metro
If you were converting a "small car" today, would you rather used a late
model Ford Festiva or Geo Metro. I looked at both cars earlier today and I
believe the Festiva to be a superior conversion candidate. But, I am
interested in what others have to say, and why other people aren't choosing
the Festiva.
In my opinion, advantages of the Festiva:
There is at least 2.75" more length to fit a motor which opens up a lot more
options than the 8" ADC.
- You could even easily fit a Warp 9" for some serious performance.
Battery mounting appears to be easier, especially if you take out the rear
seat, which is very easy Currently, you may be able to get a donor car
pretty inexpensively
In my opinion, disadvantages of the Festiva:
No off the shelf kit, as far as I know
Few examples to work from
Parts availability - 5 years from now - is questionable The cars are
generally older and more difficult to find in low mileage Stock brakes seem
a little small - from what I could tell from the disassembled car
I would like to know what others think, and why they decided to go with the
Metro rather than the Festiva. I think the Festiva with the 9" motor and 14
x
12 V AGM batteries and a 1k Zilla controller locked in 2nd gear would make a
great car. I think better than a comparable Metro which would be limited to
a 8" ADC and 12 x 12 V batteries (I've heard space issues). Anyone need to
correct me?
--- End Message ---
--- Begin Message ---
At 06:59 AM 12/24/05 -0700, you wrote:
I intend to build an EV using AC. So far, I've found electroauto and metric
mind. Are there others?
ElectroAuto sells Solectria stuff. Isn't Solectria out of business? Has
anyone bought this system?
Solectria is not out of business. They merged with a Canadian company, and
changed their name to Azure Dynamics. The same people are staffing the
same location in Massachussetts, producing the same line of components.
Shari Prange
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 ---
I'd still say the 92-95 Honda Civics are a far
superior candidate to either of the rigs mentioned.
It simply has a huge spare tire well that shrieks,
"I'm MADE for flooded USBatts!" I also consider it a
safer roll cage in the event of accident, and the fact
is, there were, and still are, 20-25,000 running off
the line PER MONTH. You will have spare parts,
aftermarket parts, etc. for a _very_ long time.
The biggest hassle (as is with other cars, too), is
yanking the heater core, and swapping the power rack
for a manual one.
Newbies, if you're interested, inquire about the
DVD/VHS.
I'd start making a kit available, (contactor mount,
controller mount, throttle mount, motor/vac. pump
mount, heater relay mount), but I'm just not convinced
there is a market at the ready, yet. And I use DCP
DCDC converter and controller, which don't quite exist
anymore.
peace,
--- Don Cameron <[EMAIL PROTECTED]> wrote:
> Nothing wrong with blazing a new trail. My New
> Beetle EV is only one of
> three in the world.
>
> What is nice about the Metro is that there is a lot
> more expertise available
> if you want parts or advice. Before I did the New
> Beetle conversion, I
> purchased a 96 Metro, and it has enough room to
> accommodate a 9" ADC motor.
>
>
> good luck.
> Don
>
>
>
>
> Victoria, BC, Canada
>
> See the New Beetle EV Conversion Web Site at
> www.cameronsoftware.com/ev/
>
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] On
> Behalf Of [EMAIL PROTECTED]
> Sent: December 26, 2005 1:36 PM
> To: [email protected]
> Subject: Festiva or Metro
>
> If you were converting a "small car" today, would
> you rather used a late
> model Ford Festiva or Geo Metro. I looked at both
> cars earlier today and I
> believe the Festiva to be a superior conversion
> candidate. But, I am
> interested in what others have to say, and why other
> people aren't choosing
> the Festiva.
>
> In my opinion, advantages of the Festiva:
> There is at least 2.75" more length to fit a motor
> which opens up a lot more
> options than the 8" ADC.
> - You could even easily fit a Warp 9" for
> some serious performance.
> Battery mounting appears to be easier, especially if
> you take out the rear
> seat, which is very easy Currently, you may be able
> to get a donor car
> pretty inexpensively
>
>
> In my opinion, disadvantages of the Festiva:
> No off the shelf kit, as far as I know
> Few examples to work from
> Parts availability - 5 years from now - is
> questionable The cars are
> generally older and more difficult to find in low
> mileage Stock brakes seem
> a little small - from what I could tell from the
> disassembled car
>
> I would like to know what others think, and why they
> decided to go with the
> Metro rather than the Festiva. I think the Festiva
> with the 9" motor and 14
> x
> 12 V AGM batteries and a 1k Zilla controller locked
> in 2nd gear would make a
> great car. I think better than a comparable Metro
> which would be limited to
> a 8" ADC and 12 x 12 V batteries (I've heard space
> issues). Anyone need to
> correct me?
>
>
'92 Honda Civic sedan, 144V (video or DVD available)!
www.budget.net/~bbath/CivicWithACord.html
____
__/__|__\ __
=D-------/ - - \
'O'-----'O'-'
Would you still drive your car if the tailpipe came out of the steering wheel?
Are you saving any gas for your kids?
__________________________________________
Yahoo! DSL Something to write home about.
Just $16.99/mo. or less.
dsl.yahoo.com
--- End Message ---
--- Begin Message ---
They are both cheap cars, with all that implies.
The Kia Pride (Ford Festiva) was in production for its home market (S. Korea)
until the early 2000s and many examples were sold worldwide, so I would
expect spares to be as widely available as for the Metro (Swift, etc.) and for
about as long. It is a fairly sturdy and substantial chassis and though I
don't
have personal experience I would think that the squared-off lines would make
underhood battery placement more flexible. Again, I haven't tried it, but you
may find that suspension and/or brake parts for the later Kia Avella (Ford
Aspire) and Kia Rio interchange or can be adapted. These cars are the
stablemates and direct descendents of the Pride.
OTOH, the Metro is a nicer looking car, IMO. It's been converted more often,
so there will probably be more collective wisdom to help out in case of
problems.
--- End Message ---
