EV Digest 6847
Topics covered in this issue include:
1) RE: 95 BMW 525i conversion
by Jim Waite <[EMAIL PROTECTED]>
2) Re: 95 BMW 525i conversion
by Victor Tikhonov <[EMAIL PROTECTED]>
3) RE: 95 BMW 525i conversion
by "Roger Stockton" <[EMAIL PROTECTED]>
4) Re: Energy loss in an EV and range now- rolling resistance
by GWMobile <[EMAIL PROTECTED]>
5) Re: Energy loss in an EV and range
by GWMobile <[EMAIL PROTECTED]>
6) Re: EV's are less maintenance?
by [EMAIL PROTECTED]
7) RE: Anybody tried battery switching from parallel strings to series
=?UTF-8?B?c3RyaW5ncz8=?=
by Tim Humphrey <[EMAIL PROTECTED]>
8) High Speed Electric Winch
by "shoredrivevb" <[EMAIL PROTECTED]>
9) Re: Energy loss in an EV and range
by GWMobile <[EMAIL PROTECTED]>
10) High Speed Electric Winch
by trev scribby <[EMAIL PROTECTED]>
11) Re: Anybody tried battery switching from parallel strings to series
strings?
by "Marty Hewes" <[EMAIL PROTECTED]>
12) RE: Anybody tried battery switching from parallel strings to series
strings?
by "Dale Ulan" <[EMAIL PROTECTED]>
13) Re: 95 BMW 525i conversion
by Lee Hart <[EMAIL PROTECTED]>
14) Re: Quickest ET ever on lead acid
by Lee Hart <[EMAIL PROTECTED]>
15) Re: Quickest ET ever on lead acid
by MIKE WILLMON <[EMAIL PROTECTED]>
16) Re: 95 BMW 525i conversion
by Tehben Dean <[EMAIL PROTECTED]>
17) TdS Report #5: Hot West Philly High School sports car, the "Hybrid Attack"
comes to NJ
by [EMAIL PROTECTED]
18) RE: 95 BMW 525i conversion
by "Roger Stockton" <[EMAIL PROTECTED]>
19) Re: AC vs DC performance (was: 95 BMW 525i conversion)
by "Zeke Yewdall" <[EMAIL PROTECTED]>
--- Begin Message ---
FWIW....
--<Roger wrote>--
I don't know that a 144V flooded pack is even an option anyway: can it
physically fit? Remember, floodies have to be installed vertically, and
must be accessible from above for watering and cleaning, etc. Even
cramming the engine bay and trunk full may not be enough without
tossing the rear seat and stuffing more where it used to be.
--<snip>--
There should be plenty of room (and w/o removing the rear seat).
The 3-Series had Six Group 31's in the trunk;
http://austinev.org/evalbum/popupimg.php?446
and Six under the bonnet;
http://austinev.org/evalbum/popupimg.php?447
(the two you can't see are underneath the top four at each end with
just enough access to check cells & re-tighten connections.)
[Note: Plexiglas safety covers and web/strap tie-downs were removed for
the photos]
--- End Message ---
--- Begin Message ---
Miami, http://www.proev.com/C1Cont.htm has his phone and addresses info.
Victor
Guy Stockwell wrote:
Where is Cliff located?
--- End Message ---
--- Begin Message ---
Jim Waite wrote:
> There should be plenty of room (and w/o removing the rear seat).
>
> The 3-Series had Six Group 31's in the trunk;
> http://austinev.org/evalbum/popupimg.php?446
>
> and Six under the bonnet;
> http://austinev.org/evalbum/popupimg.php?447
> (the two you can't see are underneath the top four at each end with
> just enough access to check cells & re-tighten connections.)
I'm not familiar enough with the dimensions of the 5-series vs the
3-series to say if there will be enough room or not, but judging by the
space consumed by 12 group 31's in these pictures, it looks to me like
it would absolutely be necessary to ditch the rear seat to fit 24-6Vs in
a 3-series.
The 6Vers are taller than a group 31, so stacking them 2 high under the
bonnet is unlikely to be an option. 2 6Vers also have a larger
footprint than a single 12V group 31, so you can't even fit 8 of them up
front (the equivalent of the 4 upper group 31's). Maybe 6: 2 rows of 3
is a bit longer, wider and taller than the 4 group 31's. That leaves 16
6Vs to squeeze into the rear where 6 group 31's fit comfortably... Ain't
likely to happen. ;^>
Don't forget that 24 T105s is almost exactly 2x the weight of 12 group
31's. It's a lot of battery to squeeze into any car, right at the limit
of what is possible and probably in excess of what is reasonable and
safe with respect to observing the GVWR.
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
This ratio of weight to rolling resistance to wind resistance was one of
the reasons I asked about the energy cost of an extra 10 pounds in city
driving.
On Wed, 6 Jun 2007 6:12 am, Phil Marino wrote:
From: Dan Frederiksen <[EMAIL PROTECTED]>
Reply-To: ev@listproc.sjsu.edu
To: ev@listproc.sjsu.edu
Subject: Energy loss in an EV and range
Date: Wed, 06 Jun 2007 07:50:28 +0200
this might have been covered many times before here but I was talking
energy loss with my (filthy gas car owning :) friend the other day and
we arrived at the conclusion that loss through rolling resistance (and
thus car wieght) was insignificant at highway speeds compared to the
wind resistance. as little as 1 percent.
Can you tell me what data (and/or calculations? led you to this value
of 1 % ?
The US Department of Energy ( as quoted in Transportation Research
Board Specail Report 286 : "Tires and Passenger Vehicle Economy" )
presents this data for "late model mid-sized passenger cars" :
The percentage of energy loss due to rolling resistance is 31 % for
urban driving and 35% for highway driving. Quite a bit higher than
1%.
For a typical ev ( with higher weight than the typical ICE) the rolling
resistance numbers would likely be a bit higher than this.
Phil Marino
Assuming this is not entirely wrong, wouldn't this mean that a very
heavy yet small wind profile car could go just as long on a given
battery amount. and that further this high weight could be used for
many more batteries...
in other words that some elongated vehicle with a normal car
windprofile could be loaded up with a lot of lead acid and thus
achieve well past 100 mile range?
not only that but benefit further from the lower internal loss of the
battery because the discharge rate is less per battery
that perhaps some sleek estate car could be made to break the 200mile
barrier on lead acid : )
volvo, bmw, audi might have some estates with a nice wind profile
or even just a regular long but narrow sedan since you probably wont
need to stack them so high that you need the estate boot anyway.
it would have to be a 2 seater only then but wouldn't it be an
interesting challenge? : )
it presumably wouldn't be a great dragster but we don't really need
drag racing as much as range.
lead acids are so relatively cheap that it should be doable. and there
are batteries outthere that claim over 50Wh/kg but don't really know
if they are lying or not
Dan
_________________________________________________________________
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www.GlobalBoiling.com for daily images about hurricanes, globalwarming
and the melting poles.
www.ElectricQuakes.com daily solar and earthquake images.
--- End Message ---
--- Begin Message ---
Lets just run out the formula for total energy to move a car.
Its components are
Acceleration.
Aerodynamic drag
Climbing ( and decling which will be a negative result of climbing)
And frictional loss
A.Tire road
B.Coasting drivetrain
C.Wheel axle
(drivetrain, wheel/tire road friction, axle friction whihc I'd prefer
to see spearate form drivetrain so we can easily discount transmission
less vehicles.)
F=m x a (squared?) is the acceleration part
Aerodynamic drag is somewhere on the net
Climbing is the same as lifting a weight a height which is=
Frictional is what anyone have the formula?
Put a plus sign between them and I'l put them in a spreadsheet so I can
start getting typical numbers
For weight vs size aerodrag
For typical cases like
Flat city stop and go
Rolling hill cruisng
Flat hwy cruising
It would be good to have such a formula.
On Wed, 6 Jun 2007 6:12 am, Peter VanDerWal wrote:
This would be (mostly) true, if you alway ran at a constant speed on a
perfectly flat road.
However, in real life, you have hills (even small ones) and
acceleration
to consider. The energy needed to climb even a shallow grade (1%)
makes
aerodynamic drag insignificant even in normal weight EVs.
Plus, making a car longer also increases it's drag, though not at the
same
rate as making it wider.
this might have been covered many times before here but I was talking
energy loss with my (filthy gas car owning :) friend the other day and
we arrived at the conclusion that loss through rolling resistance (and
thus car wieght) was insignificant at highway speeds compared to the
wind resistance. as little as 1 percent.
Assuming this is not entirely wrong, wouldn't this mean that a very
heavy yet small wind profile car could go just as long on a given
battery amount. and that further this high weight could be used for
many
more batteries...
in other words that some elongated vehicle with a normal car
windprofile
could be loaded up with a lot of lead acid and thus achieve well past
100 mile range?
not only that but benefit further from the lower internal loss of the
battery because the discharge rate is less per battery
that perhaps some sleek estate car could be made to break the 200mile
barrier on lead acid : )
volvo, bmw, audi might have some estates with a nice wind profile
or even just a regular long but narrow sedan since you probably wont
need to stack them so high that you need the estate boot anyway.
it would have to be a 2 seater only then but wouldn't it be an
interesting challenge? : )
it presumably wouldn't be a great dragster but we don't really need
drag
racing as much as range.
lead acids are so relatively cheap that it should be doable. and there
are batteries outthere that claim over 50Wh/kg but don't really know
if
they are lying or not
Dan
--
If you send email to me, or the EVDL, that has > 4 lines of legalistic
junk at the end; then you are specifically authorizing me to do
whatever I
wish with the message. By posting the message you agree that your long
legalistic signature is void.
www.GlobalBoiling.com for daily images about hurricanes, globalwarming
and the melting poles.
www.ElectricQuakes.com daily solar and earthquake images.
--- End Message ---
--- Begin Message ---
Rich,
EV's ARE less maintenance. It sounds like yours had many repairs right at
the start. You said you paid $2500 for a junker. You get what you paid
for.
I paid $6,000 for my S10. I got what I paid for (but think I've been very
lucky). Only put out $500 for a motor brush and commutator job.
the other repairs less than $300 were due to negligence to keep the post
clamps tight and from shorting eachother thus starting a fire.
Every other dollar I've spent has been for upgrades and improvements, not
repairs.
If I compare my 10 year old gasoline car to my 10 year or more old EV, the
EV is my reliable car which I know will get me to work.
In 1 year and 10,000 EV miles, I've only had 2 tows, (one from the fire and
one from the motor needing repair). I repaired it each time.
In 1 year, the gas car had about 2 tows and 4 visits to the mechanic for
repairs and I never was the one who could repair it, so shelled out
$300-$1,000 each time to repair it.
GO EV!
--- End Message ---
--- Begin Message ---
Marty,
I think you missed the point.... The controller limits the current by varying
the pulsewidth. So essentially there is no difference between RMS and peak from
a current limiting perspective. The controller will constantly adjust the
pulsewidth to keep the RMS and peak near equal. Yeah, I know, from a waveform
perspective that sounds like a "stupid" answer. But, think about it for a
minute, the pulsewidth is constantly changing to try to provide a smooth ripple
free DC output. So RMS and peak should be near equal. Well, as near as
possible.
So yeah, it protects its devices and the motor.
Am I wrong? It won't be the first time.
--
Stay Charged!
Hump
I-5, Blossvale NY
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Marty Hewes
Sent: Wednesday, June 06, 2007 10:10 AM
To: ev@listproc.sjsu.edu
Subject: Re: Anybody tried battery switching from parallel strings to
series strings?
Thank you for the explanation Dale. What I'm wondering is if the
controller
is limiting peak current during on time to protect itself, resulting in
a
net loss of wattage delivered to the motor, before it limits RMS current
to
protect the motor? At anything less than 100% duty cycle, that peak
current
could get pretty high trying to provide the same power. If the
controller
limits based on peak current during the on time to protect itself, then
lowering battery voltage may result in more watts delivered to the motor
by
keeping the peak current out of controller protection current limiting?
When you say the motor current limit is 1000 amps, is that 1000 amps
RMS, to
avoid toasting the motor with heat, or 1000 amps peak, to avoid killing
the
controller's switching devices? Let's say it's a Zilla 1K. Is the
Zilla
limited to 1K peak during the on time to the motor, or 1K RMS to the
motor,
or something greater than 1K peak? If there is a limit to the peak
current
during on time, then there might be an advantage to keeping the battery
voltage down to avoid excessive peak currents. I'm thinking of my days
in
audio amp design, where there were two things to avoid, peak currents
and
heating effects in the output devices.
What I'm wondering is, if I'm drag racing, looking for maximum wattage
delivered to the motor, would I be better off with lower battery volts
until
RPM comes up to avoid controller peak current limiting? I'm concerned
that
if battery voltage is too high, then the current draw during on time
will be
cut back by the controller, limiting wattage applied to the motor.
Would I
be better off with lower voltage and wider pulse width to avoid the
controller limiting the on time current to protect itself? Or is a
Zilla
smart enough to increase frequency so that the current during on time is
limited by motor inductance and never ramps up enough to toast the
controller, in which case trying to match voltage applied to voltage
required would be a grand waste of time?
Thanks,
Marty
----- Original Message -----
From: "Dale Ulan" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Wednesday, June 06, 2007 12:25 AM
Subject: RE: Anybody tried battery switching from parallel strings to
series
strings?
> ....
>
> Normally a controller operates in 'continuous conduction mode' which
is
> to say that the motor current ramps UP during the switch-on time, and
> ramps DOWN during the switch-off time. The PWM frequency is chosen to
> maintain the ripple current at a reasonable amount. So the pulse
widths
> being relatively short should be fine. A freewheeling diode maintains
> the current through the motor with the MOSFET off.
>
> For motor vs. battery current limiting, you normally would set the
> motor current to some maximum (say, 1000 amps so you don't fireball
> the thing), and then limit battery current to some value so you
> don't cook that end of things. The current setpoint will be set to
> the lower of:
> a. Motor maximum current
> b. Battery maximum current / duty cycle
>
> So if the controller is running a 30% duty cycle and your battery
current
> limit is 500A, the maximum allowed motor current from the battery
current
> limitation function will be 500A / 0.300 = 1666 amps. If the motor
current
> limit is 1000 amps, then the controller will current limit at 1000
amps.
> As the speed builds up, the duty cycle will ramp up to maintain the
> current
> at 1000 amps. Once the duty cycle exceeds 50%, the motor current will
then
> drop off. At a 60% duty cycle, the desired motor current will be 500A
/
> 0.600
> = 833 amps. Since this value is lower than the motor current limit of
> 1000A,
> the controller will current limit at 833 amps. You can measure battery
and
> motor voltage and achieve the same result - depends how the controller
> designer
> wanted to do it.
>
> Note that the peaks of the current waveform (from the battery) are at
833
> amps
> but since the current draw is combined with times where there is no
> current
> flowing, then the averaged current will be 500 amps.
>
> At the high end, when the duty cycle is equal to 100%, the motor takes
> only
> what it can from the battery - the controller is not current limiting
> any more. At this point, motor back-emf controls current.
>
> The same trick is used in quite a few of the current-controlling
circuits
> that I get to design.
>
> -Dale
>
>
--- End Message ---
--- Begin Message ---
I built a "winch" to tow wakeskaters in ponds, pools, creeks,
ditches, lakes, and any small body of water. Its a 9 hp gas motor
attached to a spool holding 550 ft. of waterski rope. Wakskating is
like surfing or waterskiing behind a boat. Boats are expensive, so i
built one of these. ITs a lot of fun, but sometimes hard to explain.
Check out www.winchskating.com and click on the forums. Then click
on Winchography to see all the winch's that people around the world
have built.
I would like to try things differently. Instead of using a gas
motor, i would like to use an electric motor. Making it super quiet.
a lot cleaner, and no one else has done it that i kow of.
I have seen electric go-carts on the internet, home built from
electric motors from other applications like forklifts, golf carts,
etc..
My question is, What would be the smallest electric motor that could
power a winch to pull a 200 lb. rider across a pond at about 23-25
mph.?
Would a golf cart motor and controller be sufficient? Or a golf cart
motor and some other controller, would that even make a difference?
Thanks!
Trevor Scribner
[EMAIL PROTECTED]
757.285.4469
--- End Message ---
--- Begin Message ---
Where is this calulator located?
On Wed, 6 Jun 2007 6:12 am, Peter VanDerWal wrote:
give me a rough estimate of the percentage for a sedan at 65mph
Uve's online EV calculator indicates that for the typical conversion
moving at 60 mph, approx 25% of the energy is used to overcome rolling
resistance.
Note: this is on flat ground and assumes an average Cd.
With a more streamlined vehicle, carrying more mass (which would
INCREASE
rolling resistance), this would probably increase to 50% or more.
--
If you send email to me, or the EVDL, that has > 4 lines of legalistic
junk at the end; then you are specifically authorizing me to do
whatever I
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legalistic signature is void.
www.GlobalBoiling.com for daily images about hurricanes, globalwarming
and the melting poles.
www.ElectricQuakes.com daily solar and earthquake images.
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--- Begin Message ---
But is that true? Maybe by the time the motor sees the waveform, it's
filtered enough to be, say 50% of battery voltage at 50% on time, and look
like DC with a triangle wave ripple, so yes, after the filter, RMS is more
or less equal to peak. But the semiconductors are still turned off for half
the time, so they must be seeing twice the current the motor sees during on
time before the filtering?
I'd argue that at 50% duty cycle, peak through the semiconductors is twice
RMS during the on time, with the excess current charging filter caps (and
motor windings), and zero during the off time, the filter caps (and back
EMF) hold up the voltage and drive the motor, no?
If the only limiting factor for the semiconductors is heat, it wouldn't
matter much what the battery voltage or duty cycle are. But if
instantaneous current is a factor and is protected against, then running
excess battery voltage would cause high instantaneous currents during the
short on time and current limiting may prevent you from reaching your target
power output.
This should be answerable by observation. Can a Zilla 1K really put out 1K
motor amps at near zero motor RPM when battery voltage is high and duty
cycle is very short?
Marty
----- Original Message -----
From: "Tim Humphrey" <[EMAIL PROTECTED]>
To: "EV" <ev@listproc.sjsu.edu>
Sent: Wednesday, June 06, 2007 12:28 PM
Subject: RE: Anybody tried battery switching from parallel strings to series
strings?
Marty,
I think you missed the point.... The controller limits the current by
varying the pulsewidth. So essentially there is no difference between RMS
and peak from a current limiting perspective. The controller will constantly
adjust the pulsewidth to keep the RMS and peak near equal. Yeah, I know,
from a waveform perspective that sounds like a "stupid" answer. But, think
about it for a minute, the pulsewidth is constantly changing to try to
provide a smooth ripple free DC output. So RMS and peak should be near
equal. Well, as near as possible.
So yeah, it protects its devices and the motor.
Am I wrong? It won't be the first time.
--
Stay Charged!
Hump
I-5, Blossvale NY
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Marty Hewes
Sent: Wednesday, June 06, 2007 10:10 AM
To: ev@listproc.sjsu.edu
Subject: Re: Anybody tried battery switching from parallel strings to
series strings?
Thank you for the explanation Dale. What I'm wondering is if the
controller
is limiting peak current during on time to protect itself, resulting in
a
net loss of wattage delivered to the motor, before it limits RMS current
to
protect the motor? At anything less than 100% duty cycle, that peak
current
could get pretty high trying to provide the same power. If the
controller
limits based on peak current during the on time to protect itself, then
lowering battery voltage may result in more watts delivered to the motor
by
keeping the peak current out of controller protection current limiting?
When you say the motor current limit is 1000 amps, is that 1000 amps
RMS, to
avoid toasting the motor with heat, or 1000 amps peak, to avoid killing
the
controller's switching devices? Let's say it's a Zilla 1K. Is the
Zilla
limited to 1K peak during the on time to the motor, or 1K RMS to the
motor,
or something greater than 1K peak? If there is a limit to the peak
current
during on time, then there might be an advantage to keeping the battery
voltage down to avoid excessive peak currents. I'm thinking of my days
in
audio amp design, where there were two things to avoid, peak currents
and
heating effects in the output devices.
What I'm wondering is, if I'm drag racing, looking for maximum wattage
delivered to the motor, would I be better off with lower battery volts
until
RPM comes up to avoid controller peak current limiting? I'm concerned
that
if battery voltage is too high, then the current draw during on time
will be
cut back by the controller, limiting wattage applied to the motor.
Would I
be better off with lower voltage and wider pulse width to avoid the
controller limiting the on time current to protect itself? Or is a
Zilla
smart enough to increase frequency so that the current during on time is
limited by motor inductance and never ramps up enough to toast the
controller, in which case trying to match voltage applied to voltage
required would be a grand waste of time?
Thanks,
Marty
----- Original Message -----
From: "Dale Ulan" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Wednesday, June 06, 2007 12:25 AM
Subject: RE: Anybody tried battery switching from parallel strings to
series
strings?
....
Normally a controller operates in 'continuous conduction mode' which
is
to say that the motor current ramps UP during the switch-on time, and
ramps DOWN during the switch-off time. The PWM frequency is chosen to
maintain the ripple current at a reasonable amount. So the pulse
widths
being relatively short should be fine. A freewheeling diode maintains
the current through the motor with the MOSFET off.
For motor vs. battery current limiting, you normally would set the
motor current to some maximum (say, 1000 amps so you don't fireball
the thing), and then limit battery current to some value so you
don't cook that end of things. The current setpoint will be set to
the lower of:
a. Motor maximum current
b. Battery maximum current / duty cycle
So if the controller is running a 30% duty cycle and your battery
current
limit is 500A, the maximum allowed motor current from the battery
current
limitation function will be 500A / 0.300 = 1666 amps. If the motor
current
limit is 1000 amps, then the controller will current limit at 1000
amps.
As the speed builds up, the duty cycle will ramp up to maintain the
current
at 1000 amps. Once the duty cycle exceeds 50%, the motor current will
then
drop off. At a 60% duty cycle, the desired motor current will be 500A
/
0.600
= 833 amps. Since this value is lower than the motor current limit of
1000A,
the controller will current limit at 833 amps. You can measure battery
and
motor voltage and achieve the same result - depends how the controller
designer
wanted to do it.
Note that the peaks of the current waveform (from the battery) are at
833
amps
but since the current draw is combined with times where there is no
current
flowing, then the averaged current will be 500 amps.
At the high end, when the duty cycle is equal to 100%, the motor takes
only
what it can from the battery - the controller is not current limiting
any more. At this point, motor back-emf controls current.
The same trick is used in quite a few of the current-controlling
circuits
that I get to design.
-Dale
--- End Message ---
--- Begin Message ---
or less equal to peak. But the semiconductors are still turned off for half
the time, so they must be seeing twice the current the motor sees during on
time before the filtering?
No, the motor is an inductive filter so it filters CURRENT and not voltage.
The peak current of the semiconductor is equal to the average current at
the motor plus one-half the ripple current magnitude.
The capacitors are on the battery side of the controller, not the motor
side.
-Dale
--- End Message ---
--- Begin Message ---
Guy said:
"I'm considering a 144 volt DC system (24 T125's), but am wondering
if an AC system is a better choice. I need a 60mi+ range and would
appreciate any suggestions?"
Tehben Dean wrote:
for an AC system you will need at least a 300v pack of preferably AGM
batteries. That would be between 25 and 27 batteries which could be
smaller then the batteries in a 144v pack. When measuring the amount
of total energy there is a ah and volt tradeoff i.e. more volts less
ah and more capacity lower volts... something like that anyway
Here's how I suggest looking at it.
An electric motor by itself has a torque-speed curve -- but it is
largely meaningless unless you include the controller. What matters is
the controller+motor's torque-speed curve.
For both AC and DC systems, the torque-speed curve looks the same -- a
broad constant torque region from 0 to some RPM, then a downward-sloping
region, and finally a cutoff point at the motor's maximum allowable RPM.
Using ASCII art (view with a fixed width font):
torque
|______________
| \
| \
| \
| |
|_________________|____RPM
Torque is proportional to current. RPM is proportional to voltage.
Horsepower is torque x RPM.
DC systems tend to be lower voltage (because a DC motor's commutator
limits the maximum RPM) and higher torque. AC systems tend to be higher
voltage (because AC motors can stand higher RPM) and lower torque. As
long as you pick motors+controllers with the same product of torque and
speed, you have the same horsepower; thus they will perform the same in
a given vehicle (when the gearing and other details are equivalent).
whenever you talk about AC and compare it to DC are you assuming the
AC system is 300v?
Almost all the available AC systems are built for about 300v. They work
with less, but of course you get less horsepower. There are a few low
voltage AC systems (Solectria built some for 144v, and there are a few
72v systems for forklifts), but they are generally lower power than what
people want for a road-going EV.
It is perfectly possible to design a 100kw 144v AC system -- but no one
has done so yet. No one wants to pay for the six 1000 amp switches it
would require.
even with the AC system, he still won't have the amount of torque as
his old ICE? When his 3-phase AC motor is revved up around 9,000rpm's
and it is coupled to the transmission, surely there is going to be
some serious torque at the wheels?
Exactly. The horsepower is all there; but at higher rpm and lower
torque. You just need a gear reducer. Maybe it can be the old
transmission; just leave it in 2nd or 3rd gear. But most normal car
transmissions aren't built for 13,000 RPM. There are questions about how
long they would hold up. Most AC EVs have therefore used custom gear
reducers that *are* designed for these speeds.
--
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in -- Leonard Cohen
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
--- End Message ---
--- Begin Message ---
The Ford/Autolite "Lead Wedge" was built as a high-speed streamliner in
the 1970's, but I remember it touring the country and making runs at
various drag strips. It was geared down for best 1/4-mile times, and
running ordinary Autolite lead-acid starting batteries. Anyone know what
kind of times it was turning in?
--
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in -- Leonard Cohen
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
--- End Message ---
--- Begin Message ---
Here's a nice article with images of the Lead Wedge
http://www.brianharney.net/wheels/hotrod/hr692044.htm
----- Original Message -----
From: Lee Hart <[EMAIL PROTECTED]>
Date: Wednesday, June 6, 2007 2:17 pm
Subject: Re: Quickest ET ever on lead acid
To: ev@listproc.sjsu.edu
> The Ford/Autolite "Lead Wedge" was built as a high-speed
> streamliner in
> the 1970's, but I remember it touring the country and making runs
> at
> various drag strips. It was geared down for best 1/4-mile times,
> and
> running ordinary Autolite lead-acid starting batteries. Anyone know
> what
> kind of times it was turning in?
>
> --
> Ring the bells that still can ring
> Forget the perfect offering
> There is a crack in everything
> That's how the light gets in -- Leonard Cohen
> --
> Lee A. Hart, 814 8th Ave N, Sartell MN 56377,
> leeahart_at_earthlink.net
>
--- End Message ---
--- Begin Message ---
Lee A. Hart wrote:
even with the AC system, he still won't have the amount of torque as
his old ICE? When his 3-phase AC motor is revved up around 9,000rpm's
and it is coupled to the transmission, surely there is going to be
some serious torque at the wheels?
Exactly. The horsepower is all there; but at higher rpm and lower
torque. You just need a gear reducer. Maybe it can be the old
transmission; just leave it in 2nd or 3rd gear. But most normal car
transmissions aren't built for 13,000 RPM. There are questions
about how long they would hold up. Most AC EVs have therefore used
custom gear reducers that *are* designed for these speeds.
So can't you just use the stock transmission and shift gears to keep
the rpm's below 7,000 or something. Heck I like driving a stick-
shift! ;D
I guess you would have to make sure you don't get clutch happy with
all that torque from the electric motor waiting to grind it to
bits... :P
Tehben Dean
-Lithium batteries are totally <accent>sweeet!</accent>... but
don't think about them, its bad for your morale-
--- End Message ---
--- Begin Message ---
TdS Report #5: Hot West Philly High School sports car, the "Hybrid Attack"
comes to NJ
The 21st Century Automotive Challenge, 9 June 2007, Westampton NJ
Student-Built Cars in Competition
On Saturday June 9th math teacher and auto club advisor of West Philadelphia
High School, Simon Hauger, brings the club students and their snazzy-looking
car to the campus of the Burlington County Institute of Technology (BCIT) to
defend the school's title at the annual Tour de Sol alternative fuel
transportation championship. Several Burlington County College students have
determined to out-drive and out-perform the West Philadelphia "Hybrid Attack",
but, it will be difficult for anyone to beat the car and team from West Philly,
who welcome all challengers. The obstacle course testing driving skills and
car handling characteristics will be run in the late afternoon.
Methacton High School, BOCES from Middletown, New York, and St Marks Episcopal
Academy will also have student built entries. Methacton and St Marks are
schools who collect energy from solar panels to store in the vehicle batteries.
The "Hybrid Attack", West Philly's top performing biodiesel sports car, won
acclaim at the recent Philadelphia Auto Show and has been featured on the
Discovery Channel Future Cars special.
This event, called "The 21st Century Automotive Challenge" has attracted
leaders in the alternative energy field such as David Goldstein, president of
the Electric Vehicle Association of Greater Washington DC (EVA/DC) and Robert
Wills, the technical director of the Tour de Sol for the past 19 years.
Hybrid-Electric Cars in Competition
Al Walker is an expert on the Toyota Prius Hybrid. He will compete in the 150
mile "Drive to the Shore", against several other hybrid car drivers, to see who
can achieve the most efficient, fuel-saving drive.
Al will also answer Prius questions for both participants and the public
(complete with computer demos of how the car works) Saturday evening after the
event at BCIT and Sunday at the Earth Fair on the Delaware River in Burlington
NJ.
The Tour de Sol: Then, Now, and in the Future
The Tour de Sol is in transition, as it alway has been, in a day and age when
drivers of all cars are facing tough times at the gas pump. The Tour started
as a solar-power-only car race. It changed over time to include
plug-in-charged battery-power-only cars and trucks, then hybrid-electric cars
that used fuel, and plug-in power, and sometimes solar energy to drive down the
road. Eventually, it included many variatons on the theme "sustainable
transportation", ranging from electric scooters to full-size hybrid-electric
city transit buses.
Nancy Hazard, the director of the Tour de Sol for 18 consecutive years, now
runs her own sustainability consulting firm. Nancy will address participants,
volunteers, and the welcomed public at the award and student presentations
ceremonies at the Burlington County Emergency Services Training Center
adjoining the BCIT campus, about 7pm Saturday evening. Her topic will provide
an historical perspective of the Tour de Sol and answer some of the questions
as to where did we come from, where are we, and where do we go from here?
Public Display on Sunday, 10 June 2007, Burlington NJ
Sunday the cars will be on display at the annual Burlington County Earth Fair
at Historical Smithville Park in Burlington. The Boyertown Museum of Historic
Vehicles will have an old operational Detroit Electric in mint condition on
display. A promotion firm from New York City will have a classic Checker Taxi
on display.
For more information contact
Mr. Oliver H.Perry
609 268 0944
609 922 7275
[EMAIL PROTECTED]
Sponsored by the Eastern Electric Vehicle Club
http://www.EEVC.info
http://www.EEVC.info/eevc_html_events.html
- - - -
The 2007 TdS Reports are actually about the "21st Century Automotive
Challenge" hosted by the The Eastern Electric Vehicle Club (EEVC).
The complete set of Tour de Sol Reports for 2007 can be found at:
http://www.AutoAuditorium.com/TdS_Reports_2007
The complete set of past Tour de Sol Reports can be found at:
http://www.FovealSystems.com/Tour_de_Sol_Reports.html
- - - -
The above is Copyright 2007 by Michael H. Bianchi.
Permission to copy is granted provided the entire article is presented
without modification and this notice remains attached.
For other arrangements, contact me at +1-973-822-2085 .
- - - -
For more on the "21st Century Automotive Challenge", see the web page at
http://www.EEVC.info
--- End Message ---
--- Begin Message ---
Tehben Dean wrote:
> So can't you just use the stock transmission and shift gears to keep
> the rpm's below 7,000 or something. Heck I like driving a stick-
> shift! ;D
Of course you can! Also note that the AC drives you can actually buy
don't spin to 13000+RPM anyway, browsing the Metricmind site it appears
that 9000-10000RPM max is more common (although there is one motor
listed that almost gets there with a max of 12500).
Just because the motor is capable of running at 10000RPM doesn't mean
you have to let it spin that high. Set the inverter to rev limit at
6000-7000RPM to be compatible with your ICE tranny and relax knowing
that it isn't even close to flying apart (unlike our common DC motors
that really are at risk at spontaneous dissassembly if operated much
above 5500RPM (give or take) unmodified).
A 4-banger ICE will redline at 6000RPM or more, so you know the stock
flywheel, clutch and tranny will take it, even if the tranny does wear
faster if operated continuously at this sort of speed. "Faster" is
relative anyway; a 4-banger that redlines at 6000-6500RPM might be
turning 4000RPM cruising on the highway and still get 100K+ miles out of
the tranny.
> I guess you would have to make sure you don't get clutch happy with
> all that torque from the electric motor waiting to grind it to
> bits... :P
More of a risk with the DC system actually, since you don't need to use
the clutch to start off and the DC system will typically have greater
stall torque than available AC drives.
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
Thanks. You are right about the controller availability. At least so
far, the largest one I've found is about 400amps, 72 volts....
I didn't realize the difference in nomenclature between separately
excited and shunt motors. Another thing that my EE degree didn't
bother to point out (they were more into training powerplant and
transmission line engineers, which was not my thing).
Z
On 6/5/07, Jeff Major <[EMAIL PROTECTED]> wrote:
Hi Zeke,
I'll take a shot at a couple of your questions.
--- Zeke Yewdall <[EMAIL PROTECTED]> wrote:
<snip>
> My question is about the DC systems. I assume that
> all of these
> discussions have been referring to series DC motors.
> What type of
> characteristics can I expect from a separately
> excited DC motor?
All depends on how you control it. It is possible to
pretty much emulate the series motor characteristic
(speed torque map) with a separately excited motor,
having the same armature, with the proper control.
The advantage with the separately excited system is
more control with the field making reversing, speed
limiting and regeneration easier. Possible
disadvantages are a more complex control, lower
inductance in the armature circuit and commutation
issues (brush arcing). It is possible that a 13" GE
sepex has interpoles which will aid commutation.
> I've
> got one of the 13" GE separately excited motors
> (21HP rated at 96
> volts), with a base rpm of 1,000 at 96 volts.
> Planning on running it
> at 144 or 120 volts I think. It's rated for a
> maximum of 144 volts I
> believe.
>
> I sort of assumed that the torque of the series
> motor was better for
> DC applications -- otherwise why would everyone use
> them instead of
> the shunt motors.
My guess is that the series motors are more readily
available as well as controllers for series motors, in
the size and price range for EVers. There has been a
number of golf carts and forklifts switch from series
to sepex.
> However, I did price out a new
> version of my motor
> and found that they are now about $6,000 from GE.
That is probably service replacement pricing.
Equivalent series and sepex motors should cost about
the same. Same amount of steel and copper.
Differences may arise in production volume or special
features in the motor, such as interpoles.
<snip>
> FYI, the reason I went through the trouble to find a
> used shunt motor
> was that I need regenerative brakes.
Now you say shunt motor whereas before you said sepex.
Sepex motors generally have lower voltage field
windings than shunt motors which infer the field
voltage will be equal to the nameplate voltage. With
a shunt motor, it will be difficult to emulate series
motor performance, namely starting torque.
Realize that regenerative braking will require
control.
<snip>
>
> Comments?
>
> Zeke
Good luck,
Jeff
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--- End Message ---
