EV Digest 2665
Topics covered in this issue include:
1) RE: CalCars - A non-profit way to get EV's rolling
by "Chris Tromley" <[EMAIL PROTECTED]>
2) RE: getting OT, Segway
by "Crabb, David" <[EMAIL PROTECTED]>
3) Re: Motor, surprise!
by Peter VanDerWal <[EMAIL PROTECTED]>
4) OT? - Stationary Solar charging Low voltage EV?
by [EMAIL PROTECTED]
5) Re: Motor, surprise!
by Peter VanDerWal <[EMAIL PROTECTED]>
6) RE: Motor, surprise!
by "Andre Blanchard" <[EMAIL PROTECTED]>
7) RE: getting OT, Segway
by Peter VanDerWal <[EMAIL PROTECTED]>
8) Re: Motor, surprise!
by Lee Hart <[EMAIL PROTECTED]>
9) Re: OT? - Stationary Solar charging Low voltage EV?
by "Roy LeMeur" <[EMAIL PROTECTED]>
10) Motors from another universe
by Peter VanDerWal <[EMAIL PROTECTED]>
11) RE: Motors from another universe
by Humphrey Timothy H Contr AFRL/IFEC <[EMAIL PROTECTED]>
12) RE: Motors from another universe
by Peter VanDerWal <[EMAIL PROTECTED]>
13) Re: Bearing grease.
by "David Roden (Akron OH USA)" <[EMAIL PROTECTED]>
14) Re: Heibao, AC motors, wind your own, etc.
by "David Roden (Akron OH USA)" <[EMAIL PROTECTED]>
15) Re: getting OT, Segway
by "David Roden (Akron OH USA)" <[EMAIL PROTECTED]>
16) Re: CalCars - A non-profit way to get EV's rolling
by "David Roden (Akron OH USA)" <[EMAIL PROTECTED]>
17) Preferring idiot-proof solution (Re: Reality closing in)
by Victor Tikhonov <[EMAIL PROTECTED]>
18) RE: Reality closing in - LeSled wiring and universal input relays
by "David Roden (Akron OH USA)" <[EMAIL PROTECTED]>
19) Re: Non-profit would never fly (was RE: ZAP RAP FEVER: page to sell or trade your
EV)
by "David Roden (Akron OH USA)" <[EMAIL PROTECTED]>
20) Re: EVLN(RAV4 EV not canceled due to low demand, GM's vacuum tube thinking)
by "David Roden (Akron OH USA)" <[EMAIL PROTECTED]>
21) Re: ADC 8" testing
by "David Roden (Akron OH USA)" <[EMAIL PROTECTED]>
--- Begin Message ---
John RA Benson posted for Felix from CalCars:
> We hope to raise funds initially from up approximately 1000
> Charter Sponsors, at $95, sufficient to bring on 3 or 4
> consultants to move this initiative forward, including people
> with substantial industry expertise and credibility. We
> intend to advance this effort to the point where we can make
> a credible proposal (buttressed by the number of Sponsors who
> are demonstrably serious buyers) to one of the car companies
> that might retrofit their existing vehicles, most likely
> Toyota, Hyundai, Honda or Ford, see
> http://www.calcars.org/vehicles.html
Hi Felix,
I think you have taken on a noble quest. Allow me to provide some
insight from the perspective of the EV community. Every effort on the
part of the major automakers with respect to EVs has had the effect of
ensuring EVs never materialize as a real force in the market. Every
single one. It may be argued that merely producing vehicles like the GM
EV1 and Honda EV+ should advance the cause of EVs. However, the control
of those programs by the manufacturers was total. When the programs
were ended (as planned), the manufacturers complained loud and long
about how hard they tried, and still EVS were an utter failure in the
marketplace. Those closer to the programs could easily see that those
failures were at best managed with unbelievably high levels of corporate
incompetence, and at worst intentionally engineered to showcase the
"failure".
Even Toyota's RAV4 EV fits into this group. Granted, they are actually
available for sale to the public. But they were sold with a charging
system that is incompatible with any existing charging infrastructure
that currently exists, guaranteeing their utility is minimal. It would
have been an easy, no-cost change to outfit them to use existing
infrastructure. And then they discontinued the line, making the few
cars sold instant orphans.
No one knows why the automakers are so uniformly and vehemently against
EVs. (Although opinions are quite plentiful.) The inescapable
conclusion is that they will not be receptive to anything that promotes
EVs. I believe your notion to present an automaker with a small but
committed buyer pool and get a favorable response (never mind real cars)
is naive. A plug in hybrid will allow the public to experience pure
electric transportation, which many will prefer. They simply won't
produce one unless forced. I think your current approach is destined to
fail.
>From the very beginning, automakers have strenuously resisted having
what they build dictated to them by special interest groups. The only
way they have acted in a responsible manner is when forced by
government. That is where I suggest you focus your efforts. Do you
really believe we would have any of the safety features or smog control
we now take for granted without government intervention?
Chris
--- End Message ---
--- Begin Message ---
Not everyone can ride bikes.
Some are not able to bend over well.. some have knees that are not conducive
to repeated
bending.
This, however could be a good argument about using the segway on the way to
the gym..
provided you don't suffer the above maladies and are just going to work the
upper body
/swim, etc
this vehicle can't be everything to everyone.
perhaps there are not many, but people with one foot certainly might find it
useful..
and may draw smiles versus stares if they are in a wheelchair.
Andrew King wrote:
> Joseph
> I guess I'm still not seeing what I could do on a Segway that
> I couldn't
> do on my old 10 speed.
--- End Message ---
--- Begin Message ---
> "No, EMF stands for Electro Motive Force. It IS voltage not the magnetic
> force. The magnetic field created by the back EMF is a secondary product
> of the voltage flowing in the coils."
>
> OK EMF is driving the motor so back emf is what ...driving the motor
> too...nope, sorry back EMF is anti EMF if you like, if it was aiding the
> motor they would call it forward EMF.
Back EMF is the voltage created in a motor by the coils (which also
happen to be energized by the applied voltage) moving through the
magnetic field. This created voltage is in opposition to the applied
voltage.
The issue here is that in order for a motor to work you need a magnetic
field and an energized coil that pushes against that field. In order
for the motor to be useful it must turn, this turning means that our
energized coil must move through the magnetic field correct?? (hint the
answer is YES)
Whether it is energized or not, when you move a coil through a magnetic
field it creates a voltage, called back EMF. It is impossible to move
our coil through a magnetic field without creating this voltage
>
> "It does if you disconnect the battery. He was pointing that out to show
> that Back EMF does not resist the turning of the motor by itself. It is
> not a loss. It is simply a property of motors (and generators since
> they are both the same thing)."
>
> Yes I se that point here but mine is equally valid that there is never a
> time when power is applied to a motor that there is not a closed circuit and
> therefore there is always back EMF.
>
Huh? There is back EMF in a motor that is turning (assuming at least a
residual magnetic field) whether there is closed circuit or not.
I often have power applied to my motor when there is no closed circuit.
It's called coasting, I let my foot off the throttle and the motor
contactor opens. The power in this case is being applied to the motor
via the wheels and transmission.
Besides what is you point? The Back EMF does not slow the motor down
until it is higher than the applied voltage. This only happens in
vehicles with Regen braking and is a desirable feature.
> "Current is only actually flowing in one direction. Which direction
> depends on whether the Back EMF is higher or lower than the applied
> voltage."
>
> Yup I will agree with this one my point here is how much current is flowing,
> when the switch turns on and you comprehend what im saying here you will see
> that I am not trying to get more out than in, im simply trying to say that
> you can get more out from what you put in.
Again Huh? At any case you are wrong. People have built motors (with
back EMF) that run close to 98% efficient, how exactly are you going to
get more power out than that? The 2% is going up in friction and
windage losses and a tiny bit in magnetic losses.
One more time since you seem to keep missing it: Back EMF is NOT A
LOSS!!! it's just a fact of life.
>
> "A motor can switch to being a generator by simply forcing it to spin
> faster than it wants to with the applied voltage, for example going down
> hill with a PM motor. It works as a motor going up the hill and as soon
> as you go down hill, and pick up some speed, it works as a generator and
> slows you down."
>
> Yes precisely, but if you remove the back EMF, it will no longer generate
> when it is being over run.
>
Except you can't remove the back EMF. If you could it would be a race
to see whether the motor self destructed from over reving or melting
down.
Besides the better EV motor/controllers use Back EMF for Regen which is
highly desirable.
--- End Message ---
--- Begin Message ---
Well my 72 volt EV Rabbit may just hit the road soon, with lots of work,
help and hospitality from Bob Rice and Jack Gretta. Since it's only going to
be a station car I think it would be cheapest to leave it as is:
Curtis 72 volt controller, 6.7" Advanced DC motor, 6vdc batteries, no DC/DC
It will be going <8 miles a day on one road with a 25mph speed limit.
Sitting at an uncovered lot at the train station for 12-15 hours after ~4
miles mostly down a slight grade then going 4 miles back up.
I might put in a small solar panel to keep the 12 volt up during the day but
I have reservations about dragging some around with me to charge the car, in
addition to effectiveness reasons I fear someone breaking the expensive
panels. I have already gotten my plain EV blazer defaced a bit while it was
parked there in the last couple weeks, if not I may have gotten one just for
"show" and to trickle the pack a bit during the long day.
So I would like to have some panels at home charge some batteries so that I
can charge the rabbit when I get home. I don't know how easy it would be to
dump charge them and would rather not babysit it everyday if possible. Are
there DC input chargers or ones that work off of the cheaper modified sine
wave inverters though it seems silly to go through an inverter to get it to
AC just to have the charger DC it.
Note: Grid intertie is expensive in my city time consuming and a nightmare
:-(
Mark Hastings
'83 S-10 EV Blazer
www.geocities.com/evblazer
--- End Message ---
--- Begin Message ---
> "Very few here would be surprised we put current backwards through our
> batteries every time we recharge them. You might be surprised how fast
> reversed current flow can damage a fully charged battery."
>
> This is one of those things that I call "misinterpretation by assumption".
>
> Because we have all charged batteries and discharged them we know that we
> put the power in and take it out and from this we assume that it comes out
> one way and goes back in the other, this is of course not true.
>
> You can prove this for yourself by taking a motor, a battery and its battery
> charger and connecting the motor to the battery, if you now note the
> direction of the rotation of the motor and which wires are connected to
> positive and which are connected to negative and then remove the battery and
> replace it with the battery charger, so that the battery charger has
> positive going to the wire that the batteries positive terminal was
> connected to and also the negative to the wire that the batteries negative
> terminal was connected to and check the direction of rotation you will see
> that they are the same.
>
> What this shows is that a battery does not charge by having current forced
> into it in the opposite direction to the current that came out, but rather
> that it is in parallel with the charger and a cascade effect is the cause of
> charge as the energy "cascades" into the battery so that it comes up to the
> same level as the charger.
>
You have just proved the point that you are trying to disprove. Again
you misunderstand what is happening and YOU make a false assumption.
The charger is indeed the same polarity as the battery. The difference
is that the charger is a higher potential( higher voltage) than the
battery so current flows INTO the battery instead of out of it. Current
flow through the battery does indeed reverse when charging, that is
fundamental to how batteries operate.
You can see this by leaving one side of the motor connected to the
positive side of the battery and connecting the positive side of the
charger to the other side of the motor. The motor will now run in the
opposite direction (assuming a permanent magnet motor) showing that
current flow has reversed.
Of course if it's a series wound motor it runs in the same direction
regardless of current flow.
Making up silly words (like "cascade effect") doesn't change the nature
of it.
> You can further test this by placing a flat battery in line with a charged
> battery and leaving them over night, the following morning you will have 2
> half charged batteries as the charged one has cascaded into the flat one
> until equilibrium has been reached.
Again the charged battery is at a higher potential than the discharged
battery. Current flows out of the charged battery and into the
discharged battery. Put a motor between them and you will see it
turning. Current flow is reversed in the discharged battery.
> Isn't this exactly what I said "that the shaft output of a motor can be
> defined as a/v in, minus a/v out, minus resistance" ?
>
Actually it's minus losses. Resistance is only part of one of the
losses. These is also friction, windage, and magnetic losses.
> I can see that you all seem to be able to grasp that back emf is in one way
> or another, slowing your motors yet you all seem to think this is a good
> thing.
It is a good thing. It prevents huge currents from flowing and
destroying the motors.
--- End Message ---
--- Begin Message ---
Have you tried putting an amp meter in series with the batteries? Try it
and you will find that when charging the current is indeed flowing in the
opposite direction.
I think you are having problems with the concepts of voltage, current, and
power. I suggest that you get some basic books on the subject and do some
studying.
What your experiment below shows is that batteries do charge by forcing
current through them backwards.
Andre' B. [EMAIL PROTECTED]
If something cannot be defined, it does not exist.
Isaac Newton
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of garry
Sent: Friday, March 21, 2003 9:10 AM
To: [EMAIL PROTECTED]
Subject: Re: Motor, surprise!
Hi Andre,
"Very few here would be surprised we put current backwards through our
batteries every time we recharge them. You might be surprised how fast
reversed current flow can damage a fully charged battery."
This is one of those things that I call "misinterpretation by assumption".
Because we have all charged batteries and discharged them we know that we
put the power in and take it out and from this we assume that it comes out
one way and goes back in the other, this is of course not true.
You can prove this for yourself by taking a motor, a battery and its battery
charger and connecting the motor to the battery, if you now note the
direction of the rotation of the motor and which wires are connected to
positive and which are connected to negative and then remove the battery and
replace it with the battery charger, so that the battery charger has
positive going to the wire that the batteries positive terminal was
connected to and also the negative to the wire that the batteries negative
terminal was connected to and check the direction of rotation you will see
that they are the same.
What this shows is that a battery does not charge by having current forced
into it in the opposite direction to the current that came out, but rather
that it is in parallel with the charger and a cascade effect is the cause of
charge as the energy "cascades" into the battery so that it comes up to the
same level as the charger.
You can further test this by placing a flat battery in line with a charged
battery and leaving them over night, the following morning you will have 2
half charged batteries as the charged one has cascaded into the flat one
until equilibrium has been reached.
"I think you have the concept here but there is only one current flowing and
it can only flow in one direction at any one time. Its direction is
determined by the greater EMF that of the motor/generator or that of the
battery. The amount of current is determined by the magnitude of the
difference between the motor/generator and battery EMFs and the resistance
in the path of the current."
Isn't this exactly what I said "that the shaft output of a motor can be
defined as a/v in, minus a/v out, minus resistance" ?
I can see that you all seem to be able to grasp that back emf is in one way
or another, slowing your motors yet you all seem to think this is a good
thing.
Garry Stanley
Cable.net.nz
--- End Message ---
--- Begin Message ---
Standard electric scooters can be equally useful, lighter, and a whole
lot cheaper.
On Fri, 2003-03-21 at 08:32, Crabb, David wrote:
> Not everyone can ride bikes.
> Some are not able to bend over well.. some have knees that are not conducive
> to repeated
> bending.
>
> This, however could be a good argument about using the segway on the way to
> the gym..
> provided you don't suffer the above maladies and are just going to work the
> upper body
> /swim, etc
>
>
> this vehicle can't be everything to everyone.
>
> perhaps there are not many, but people with one foot certainly might find it
> useful..
> and may draw smiles versus stares if they are in a wheelchair.
>
>
>
> Andrew King wrote:
>
> > Joseph
> > I guess I'm still not seeing what I could do on a Segway that
> > I couldn't
> > do on my old 10 speed.
>
>
--
EVDL
--- End Message ---
--- Begin Message ---
Lee Hart wrote:
>> The coils in a motor are all in pairs... The equivalent electric
>> circuit is a bunch of 1.5v batteries, all in series, with half of
>> them facing one way, and half facing the other. The net current
>> is zero, because the voltages of the two halves are identical and
>> cancel out.
Garry Stanley wrote:
> The problem is that if this is true then, when spun by an external
> means with a closed circuit your motor can not make any power
This was Edison's mistake, too. But in fact, it DOES work if you arrange
things right.
Suppose you connect a pair of flexible wires to one coil, so you can
watch its voltage as you turn the motor. The voltage will be zero, then
rise to a positive peak as the coil passes the North field pole, then
fall to zero, then fall to a negative peak as the coil passes the South
field pole, and back to zero again. The waveform is called a sine wave.
Here are the voltages for one revolution of a 12v motor.
shaft angle volts
----------- -----
0 deg. 0v
30 deg. 6v
60 deg. 10v
90 deg. 12v
120 deg. 10v
150 deg. 6v
180 deg. 0v
210 deg. -6v
240 deg. -10v
270 deg. -12v
300 deg. -10v
330 deg. -6v
360=0 deg. 0v
With a pair of slip rings, you could bring out this coil's voltage and
you'd have an AC generator (called an alternator). You could also apply
AC to this coil, and it would run as a synchronous motor. The coil
positions itself in the fixed magnetic field so the shaft angle matches
the coil voltage.
Now, let's look at the simplest DC motor; the little toy motors that
only have 3 windings and only 3 commutator bars. Notice that the coils
are spaced 120 degrees apart. Therefore, the sinewave voltages they
produce are the same, but coil 2 is shifted by +120 degrees, and coil 3
by -120 degrees.
shaft angle coil 1 coil 2 coil 3 sum of coil 1-3 voltages
----------- ------ ------ ------ ------------------------
0 deg. 0v -10v 10v 0v
30 deg. 6v -12v 6v 0v
60 deg. 10v -10v 0v 0v
90 deg. 12v -6v -6v 0v
120 deg. 10v 0v -10v 0v
150 deg. 6v 6v -12v 0v
180 deg. 0v 10v -10v 0v
210 deg. -6v 12v -6v 0v
240 deg. -10v 10v 0v 0v
270 deg. -12v 6v 6v 0v
300 deg. -10v 0v 10v 0v
330 deg. -6v -6v 12v 0v
360=0 deg. 0v -10v 10v 0v
Each coil produces its own sinewave. You could have a slip ring for
each, and have 3 separate AC alternators or motors. You could power all
three at once, with sinewaves separated by 120 degrees; this is called a
3-phase motor or alternator.
But... notice the last column. The sum of the three coil voltages just
happens to be zero at every point! That means the 3 coils can be
connected in series, and the voltages always cancel. There will never be
any circulating current around the loop.
Now let's add a commutator. It is a switch, that connects to two points
on opposite sides. Here is an illustration showing the armature, its
three coils (1 2 3), the three commutator bars (A B C), and the + and -
brushes. The armature is rotating clockwise, and the brushes remain at
the top and bottom.
positive brush
==============
+ coil 1 -
A __________ B
\ /
- \ / +
coil 2 \ / coil 3
+ \ / -
\/
C
==============
negative brush
shaft angle coil 1 coil 2 coil 3 + brush - brush voltage
----------- ------ ------ ------ ------- ------- -------
0 deg. 0v -10v 10v A & B C 10v
30 deg. 6v -12v 6v A C 12v
60 deg. 10v -10v 0v A B & C 10v
90 deg. 12v -6v -6v A B 12v
120 deg. 10v 0v -10v C & A B 10v
150 deg. 6v 6v -12v C B 12v
180 deg. 0v 10v -10v C A & B 10v
210 deg. -6v 12v -6v C A 12v
240 deg. -10v 10v 0v B & C A 10v
270 deg. -12v 6v 6v B A 12v
300 deg. -10v 0v 10v B C & A 10v
330 deg. -6v -6v 12v B C 12v
360=0 deg. 0v -10v 10v A & B C 10v
Even though each coil has only AC voltage and current (and zero DC
voltage and current), the brushes "pick off" the voltage of each coil
when it is at its postive peak. Thus, you have a DC voltage at the
brushes, and can draw a DC current from them (generator) or push current
into them (motor).
There is a considerable ripple voltage on the DC; it varies 2v (between
10v and 12v). But, that's still pretty good for such a simple motor.
Quality motors have more coils and more commutator segments, which
reduces the ripple even further.
Note that the brush is wide enough to short each coil as it crosses over
the commutator segments. But, the brush is positioned so the coil being
shorted just happens to be at zero volts. Thus, there is no wasteful or
damaging short circuit. Again, this just barely works in such a simple
motor; better motors have lots more commutator segments to improve this
effect.
> To use your own analogy here if you take 3 batteries of 2 volts
> and wire them so that one is facing opposite the other 2, then
> measure the voltage you will find you only have 2 volts...
Right! Two of the 2v cells would be discharging, and charging the one 2v
cell. There is a circulating current in this loop. This is bad; you'll
wind up with 2 dead cells and one overcharged cell. Since the energy
from 2 cells won't fit into one, the excess is burned up as heat.
But in the case of a motor, the 3 "batteries" are constantly changing
their voltage, as described above, so the circulating current is always
zero.
> The current flowing in a wire is the sum of any currents flowing
> in said wire and the direction will always be that of the greater
> voltage
Yes; this is a correct statement of the "superposition" principle. But
it is not literally true; it is one of those nice little analogies to
simplify calculation.
The superposition principle says that when you have a complex circuit
with more than one path, you can calculate the voltages and currents in
each path independently, and then add up the results to find the total
currents and voltage at each point. So if you have a 1-amp load on a
battery, and also have a 10-amp charger connected to that battery, the
battery's total current is +10amps (from the charger) -1amp (to the
load) = +9amps (charging the battery). But this does *NOT* mean that
there are literally two separate +10amp and -1amp currents flowing in
the battery wires.
--
Lee A. Hart Ring the bells that still can ring
814 8th Ave. N. Forget your perfect offering
Sartell, MN 56377 USA There is a crack in everything
leeahart_at_earthlink.net That's how the light gets in - Leonard Cohen
--- End Message ---
--- Begin Message ---
Mark Hastings wrote:
----------------------------------
So I would like to have some panels at home charge some batteries so that I
can charge the rabbit when I get home. I don't know how easy it would be to
dump charge them and would rather not babysit it everyday if possible. Are
there DC input chargers or ones that work off of the cheaper modified sine
wave inverters though it seems silly to go through an inverter to get it to
AC just to have the charger DC it.
----------------------------------
Though you can bulk charge pretty easy with dump charging, it would be
difficult to get proper finish charging or equalization this way.
Rich Rudman's PFC line of chargers accept AC or DC input, down to about 60V
or less IIRC.
Or maybe you could dump charge with a pack of the same nominal voltage as
the car's pack then finish charge with your existing charger.
HTH
Roy LeMeur Seattle WA
My Electric Vehicle Pages:
http://www.angelfire.com/ca4/renewables/evpage.html
Informative Electric Vehicle Links:
http://www.angelfire.com/ca4/renewables/evlinks.html
_________________________________________________________________
MSN 8 helps eliminate e-mail viruses. Get 2 months FREE*.
http://join.msn.com/?page=features/virus
--- End Message ---
--- Begin Message ---
Ok let's pretend we live in a universe where it is possible to build
motors without any Back EMF.
If you don't want to play along, just delete this message.
Let's calculate how powerful such a motor could be shall we?
We will start with some assumptions. First of all we will assume that
Ohm's law still applies so:
E=I*R
where E represents voltage, I represent current and R represents
resistance.
Further P=I*E
where P= Power (in watts)
This also means that P=I*I*R (via substitution)
Finally we will assume an EV size motor with an internal resistance of
0.1 ohm, only difference from reality is that this motor developes zero
Back EMF.
So what happens when we apply 10V to this motor?
In real life the motor will start spinning and back EMF will come up to
about 8.5V and the motor will draw about 15 amps.
But we are not talking about real life here, we are talking about a
universe where Back EMF doesn't exist.
So we apply 10V to our motor and the only thing limiting current flow is
the motor's internal resistance (0.1 Ohm)
Input power will therefor be 1,000 watts.
I=E/R or I=10V/0.1Ohm = 100 amps.
100 Amps * 10V = 1,000 watts.
Cool, now let's figure out our losses and then see how much power
actually ends up turning the motor shall we?
Let's see resistive losses equals the power burned up in the motors
resistance. That would be I*I*R or 100 amps * 100 amps * 0.1 Ohms =
1,000 watts.
So 1,000 watts in minus 1,000 watts in I2R losses equals zero watts to
move the motor. So the motor runs at zero percent efficiency, doesn't
turn and just generates a lot of heat.
That's no good, maybe if we applied 20V ??
20V / 0.1Ohm = 200 amps...yeah that's the ticket. Now we are putting
4,000 watts in.
Let's see I2R losses equal 200*200*0.1 = 4,000 watts
Hmm, still no movement only the motor is getting really hot now. I
think we need a fan over here...
You know what? I don't like this universe, I'm going back to reality,
see ya.
--
EVDL
--- End Message ---
--- Begin Message ---
Didn't you just describe "locked rotor".
-----Original Message-----
From: Peter VanDerWal [mailto:[EMAIL PROTECTED]
Sent: Friday, March 21, 2003 2:35 PM
To: EV
Subject: Motors from another universe
Ok let's pretend we live in a universe where it is possible to build motors
without any Back EMF. If you don't want to play along, just delete this
message.
Let's calculate how powerful such a motor could be shall we?
We will start with some assumptions. First of all we will assume that Ohm's
law still applies so: E=I*R where E represents voltage, I represent current
and R represents resistance. Further P=I*E where P= Power (in watts) This
also means that P=I*I*R (via substitution) Finally we will assume an EV size
motor with an internal resistance of 0.1 ohm, only difference from reality
is that this motor developes zero Back EMF.
So what happens when we apply 10V to this motor?
In real life the motor will start spinning and back EMF will come up to
about 8.5V and the motor will draw about 15 amps. But we are not talking
about real life here, we are talking about a universe where Back EMF doesn't
exist.
So we apply 10V to our motor and the only thing limiting current flow is the
motor's internal resistance (0.1 Ohm) Input power will therefor be 1,000
watts.
I=E/R or I=10V/0.1Ohm = 100 amps.
100 Amps * 10V = 1,000 watts.
Cool, now let's figure out our losses and then see how much power actually
ends up turning the motor shall we?
Let's see resistive losses equals the power burned up in the motors
resistance. That would be I*I*R or 100 amps * 100 amps * 0.1 Ohms = 1,000
watts. So 1,000 watts in minus 1,000 watts in I2R losses equals zero watts
to move the motor. So the motor runs at zero percent efficiency, doesn't
turn and just generates a lot of heat.
That's no good, maybe if we applied 20V ??
20V / 0.1Ohm = 200 amps...yeah that's the ticket. Now we are putting 4,000
watts in. Let's see I2R losses equal 200*200*0.1 = 4,000 watts Hmm, still no
movement only the motor is getting really hot now. I think we need a fan
over here...
You know what? I don't like this universe, I'm going back to reality, see
ya.
--
EVDL
--- End Message ---
--- Begin Message ---
Yup pretty much.
Since Back EMF * Current = power applied to turn the shaft. No Back EMF
means no power at the shaft.
> Didn't you just describe "locked rotor".
>
> -----Original Message-----
> From: Peter VanDerWal [mailto:[EMAIL PROTECTED]
> Sent: Friday, March 21, 2003 2:35 PM
> To: EV
> Subject: Motors from another universe
>
>
> Ok let's pretend we live in a universe where it is possible to build motors
> without any Back EMF. If you don't want to play along, just delete this
> message.
>
> Let's calculate how powerful such a motor could be shall we?
>
> We will start with some assumptions. First of all we will assume that Ohm's
> law still applies so: E=I*R where E represents voltage, I represent current
> and R represents resistance. Further P=I*E where P= Power (in watts) This
> also means that P=I*I*R (via substitution) Finally we will assume an EV size
> motor with an internal resistance of 0.1 ohm, only difference from reality
> is that this motor developes zero Back EMF.
>
> So what happens when we apply 10V to this motor?
> In real life the motor will start spinning and back EMF will come up to
> about 8.5V and the motor will draw about 15 amps. But we are not talking
> about real life here, we are talking about a universe where Back EMF doesn't
> exist.
>
> So we apply 10V to our motor and the only thing limiting current flow is the
> motor's internal resistance (0.1 Ohm) Input power will therefor be 1,000
> watts.
> I=E/R or I=10V/0.1Ohm = 100 amps.
> 100 Amps * 10V = 1,000 watts.
> Cool, now let's figure out our losses and then see how much power actually
> ends up turning the motor shall we?
>
> Let's see resistive losses equals the power burned up in the motors
> resistance. That would be I*I*R or 100 amps * 100 amps * 0.1 Ohms = 1,000
> watts. So 1,000 watts in minus 1,000 watts in I2R losses equals zero watts
> to move the motor. So the motor runs at zero percent efficiency, doesn't
> turn and just generates a lot of heat.
>
> That's no good, maybe if we applied 20V ??
> 20V / 0.1Ohm = 200 amps...yeah that's the ticket. Now we are putting 4,000
> watts in. Let's see I2R losses equal 200*200*0.1 = 4,000 watts Hmm, still no
> movement only the motor is getting really hot now. I think we need a fan
> over here...
>
> You know what? I don't like this universe, I'm going back to reality, see
> ya.
>
> --
> EVDL
>
--
EVDL
--- End Message ---
--- Begin Message ---
On 19 Mar 2003 at 15:21, Lawrence Rhodes wrote:
> Is there a good synthetic bearing grease that would work well in EVs.
I use Amsoil. Seems to work fine.
http://www.amsoil.com/products/ghd.html
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1991 Solectria Force 144vac
1991 Ford Escort Green/EV 128vdc
1970 GE Elec-trak E15 36vdc
1974 Avco New Idea rider 36vdc
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On 19 Mar 2003 at 20:30, Seth wrote:
> For fun, go here:
>
> http://www.brusa.li/products/e_motor_gt20_t181.htm
>
> squint and repeat after me: "swimming pool pump motor, swimming pump
> pool motor, swimming pump pool motor" ;)
Hey, that's my motor! Are you saying I should fill up the Force with water
and let the dog do laps? <g>
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David Roden - Akron, Ohio, USA
1991 Solectria Force 144vac
1991 Ford Escort Green/EV 128vdc
1970 GE Elec-trak E15 36vdc
1974 Avco New Idea rider 36vdc
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On 20 Mar 2003 at 0:43, Andrew wrote:
> if you
> want to ride any distance it makes more sense to me to have something that
> can go faster out in the street even if it can't make a U-turn in it's own
> length
Not to mention something you can SIT on.
Reminds me of "sitting buses" and "standing buses" in Seoul. Sitting buses
have more seats, but you pay more to sit. With a Segway, you pay more to
stand. Eh?
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David Roden - Akron, Ohio, USA
1991 Solectria Force 144vac
1991 Ford Escort Green/EV 128vdc
1970 GE Elec-trak E15 36vdc
1974 Avco New Idea rider 36vdc
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They're only interested in doing SUVs, no cars. Too bad.
.
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David Roden - Akron, Ohio, USA
1991 Solectria Force 144vac
1991 Ford Escort Green/EV 128vdc
1970 GE Elec-trak E15 36vdc
1974 Avco New Idea rider 36vdc
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I've heard somewhere a computer manufacturer opinion
that if you make it such that even a idiot can use it, then
only an idiot will use it. IMHO, applies to an EV as well.
A car assumes traces of intelligence in an operator's brains.
You probably won't see a label near radiator fan blades
"Don't Stick Your Fingers Here". But an idiot will, and moreover,
will sue the manufacturer (in this case may be YOU) later.
Just make it simple and obvious for unfamiliar people with common
sense and don't let to drive all others.
A determined idiot *will* find a way to damage an idiot proof thing.
I always have a brief interview with a person I'm about to let take
my car for a spin.
My 2 mm.
Victor
1sclunn wrote:
>
> >
> > Yeah, but I prefer an idiot-proof solution. I'd like to be able to lend
> > the car to someone with no EV experience and be confident they can't
> > hurt themselves.
> >
> Be sure to till them not to put gas in it .
> There were a lot of good ideas from different people . I lend my ev's to
> different people and worry about all the little things that could go wrong
> but feel that it's inportant for people to see what could be. Making them
> idiot proof is a good goal .
>
> Steve Clunn
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On 20 Mar 2003 at 16:26, Chris Tromley wrote:
> Still, if the power supply fails, the
> interlock fails without any indication.
If you use the 12v output for other "house power," you'll know if it fails.
For example, use it to light a "plugged in" indicator in the rear window
(just an LED in a box) or on the dash. Power your battery box fans with it.
Use it to pull in an relay that connects the heater to AC power. There are
lots of uses for 12v that's active only when the car is plugged in.
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David Roden - Akron, Ohio, USA
1991 Solectria Force 144vac
1991 Ford Escort Green/EV 128vdc
1970 GE Elec-trak E15 36vdc
1974 Avco New Idea rider 36vdc
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The Subject of this post, "Non-profit would never fly," could be misleading.
Your argument is correct for the rather obvious case that a for-profit
company can't build a product that doesn't turn a profit. And, similarly, a
nonprofit company can't build a product that doesn't show a revenue return.
Also, it has to take in enough revenue to continue product development for
the future. But that's no reason that "non-profit would never fly."
There are significant differences between a nonprofit and a for-profit.
A nonprofit need not pay its shareholders a dividend. It enjoys tax
advantages. It can solicit and accept more types of grants to fund its
operations. All these can be significant advantages in producing something
that has a limited market. That's one reason that public broadcasting (to
name only one endeavor) is operated by nonprofits.
Don't get me wrong, there are disadvantages to nonprofits too. One is that
you can't reward your investors when you succeed.
But let's not confuse things. Nonprofit organizations are NOT for-profits
that fail to make a profit.
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David Roden - Akron, Ohio, USA
1991 Solectria Force 144vac
1991 Ford Escort Green/EV 128vdc
1970 GE Elec-trak E15 36vdc
1974 Avco New Idea rider 36vdc
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On 20 Mar 2003 at 17:39, Bruce EVangel Parmenter wrote:
> Martin of the Air Resources Board now
> acknowledges that battery technology has not worked out the
> way air regulators had hoped in the 1990s.
>
> "Quite frankly, it pretty much has stalled," he said.
>
What rubbish. CARB caved just at the moment advanced battery technology was
beginning to come online. Their change in position was based on politics,
not technology.
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David Roden - Akron, Ohio, USA
1991 Solectria Force 144vac
1991 Ford Escort Green/EV 128vdc
1970 GE Elec-trak E15 36vdc
1974 Avco New Idea rider 36vdc
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On 20 Mar 2003 at 21:33, Lee Hart wrote:
> Sure. It will take 20-30 amps though. A 10-amp charger will probably
> trip its circuit breaker.
I also recommend making the connection with a small contactor, not by
touching a cable to the terminal. There will be a good-sized arc. I damaged
the end of a Comuta-car motor terminal once that way, and had to cut it off
to put the nut on again.
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David Roden - Akron, Ohio, USA
1991 Solectria Force 144vac
1991 Ford Escort Green/EV 128vdc
1970 GE Elec-trak E15 36vdc
1974 Avco New Idea rider 36vdc
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