EV Digest 6272
Topics covered in this issue include:
1) RE: direct drive (basic questions)
by "Dale Ulan" <[EMAIL PROTECTED]>
2) Re: Surplus Capacitors - Was: Joe Sixpack Geo: best controller...
by "Bruce" <[EMAIL PROTECTED]>
3) Re: direct drive (basic questions)
by "Tom Shay" <[EMAIL PROTECTED]>
4) Re: Unsafe Controllers
by Electro Automotive <[EMAIL PROTECTED]>
5) Re: Circuit Breaker and Contactor
by Jack Murray <[EMAIL PROTECTED]>
6) RE: Unsafe Controllers
by "Roger Stockton" <[EMAIL PROTECTED]>
7) Re: direct drive (basic questions)
by GWMobile <[EMAIL PROTECTED]>
8) Re: Proprietary "pot" required for Curtis 1204-410
by "Darin - MetroMPG.com" <[EMAIL PROTECTED]>
9) Re: Unsafe Controllers
by "Rush" <[EMAIL PROTECTED]>
10) RE: Circuit Breaker and Contactor
by "Roger Stockton" <[EMAIL PROTECTED]>
11) Re: direct drive (basic questions)
by "Kaido Kert" <[EMAIL PROTECTED]>
12) Re: New Sentra , WAS new EV business
by GWMobile <[EMAIL PROTECTED]>
13) Re: New Sentra , WAS new EV business
by GWMobile <[EMAIL PROTECTED]>
14) Re: direct drive (basic questions)
by GWMobile <[EMAIL PROTECTED]>
15) RE: Unsafe Controllers
by "Dale Ulan" <[EMAIL PROTECTED]>
--- Begin Message ---
If you are putting that gearbox (or the motor, for that matter) on the
wheel, you are adding a significant amount of unsprung weight (which you
normally try to minimize).
As for a gear-drive axle, one of the John Deere tractors I used to drive had
a planetary gearbox in each wheel so the torque on the CV joints would be
much less. But a tractor does not have a traditional suspension system, nor
the same efficiency/weight requirements that a typical EV has.
-Dale Ulan
Calgary, Alberta, Canada.
--- End Message ---
--- Begin Message ---
Both of those surplus places had interesting web sites. Thanks for the
links Lawrence.
Electronic Goldmine has 10,000uF - 10V radial electrolytic caps in a package
of 100 for $35. That's $3.50 per Farad-Volt.
http://www.goldmine-elec-products.com/prodinfo.asp?number=G4417A
They also have 680uF - 200V electrolytic caps for $1 each. That's $7.35 per
Farad-Volt.
http://www.goldmine-elec-products.com/prodinfo.asp?number=G9448
And they have .047F - 5.5V super caps also at $8 for quantity 10. That
comes out to $3.09 per Farad-Volt.
http://www.goldmine-elec-products.com/prodinfo.asp?number=G1399
Excess Solutions has 13,000uF - 25V Nippon caps for $3 each. That's $9.23
per Farad-Volt.
http://www.excesssolutions.com/cgi-bin/item/ES3463
And they also have 430mF - 125VAC Mallory caps for $6 each. That's only
$0.11 per Farad-Volt. This one seems to be a better deal than the others,
but I wondered about the 125VAC rating. Does this mean that it won't work
with DC? http://www.excesssolutions.com/cgi-bin/item/ES2353
Can anyone find better deals on capacitors than these?
_______________________________________________________________
Lawrence Rhodes wrote:
> I'm glad you asked Bruce. http://www.excesssolutions.com/ Excess
Solutions
> is my favorite place to go hunting parts. On top of a great wearhouse
they
> are also on line. If you can't find what you want there I'm sure you can
> find something elsewhere like Electronic Goldmine.
--- End Message ---
--- Begin Message ---
This might be a great way to build an EV if suitable motor-wheel
assemblies were available at reasonable prices. But they aren't
available. Motors built into the wheel hub are available for
bicycles and some are brushless and gearless. Maybe someday hub
motors for a VW sized vehicle will be available but not yet.
----- Original Message -----
From: "Jonathan Perret" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Thursday, January 04, 2007 7:43 AM
Subject: direct drive (basic questions)
I'm curious to understand how much work is involved in
converting an ICE car (VW Beetle for instance) into an electric vehicle
that has the wheeels driven directly by motors on each wheel
rather than via the existing transaxle...
for example how do you mate the motor shaft to the wheel hubs for say the
front wheels which previously (as an ICE car) weren't driven, just rolled.
thanks,
Jonathan
--- End Message ---
--- Begin Message ---
At 09:07 AM 1/4/2007, you wrote:
I find it interesting that a DC motor controller is so unsafe that
it must be completely disabled every time you release the go
pedal. That really says something.
Which controllers have failed several times?
Jack
The deadman switch does not mean the controller is "so unsafe". As I
said, we have had it happen ONCE to a customer. Since Curtis sells
hundreds of thousands of these every year, I doubt it is a frequent
problem. However, wise engineers build in safety redundancies and
"fail safes", and try to "idiot-proof" systems as much as
possible. Unfortunately, somewhere there is always a bigger idiots out there.
As an example, does it mean that gas cars are "so unsafe" because gas
pumps post warnings not to use your cell phone, not to get back in
the car while pumping, and to rest gas cans on the ground while
filling? I see people on their cell phones, and getting in and out
of cars while pumping all the time. When was the last time you heard
about one blowing up from a cell phone spark or static
electricity? Nevertheless, the warning is there because it COULD happen.
It's not that it happens so often, just that IF it does, the results
would be very bad.
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 certainly agree safety is very important, the issue is HOW TO DO IT.
I understand most of you do or have done things a certain way for years,
and think doing something different must be wrong, but you have blinders on.
Disconnecting the battery pack on every throttle lift seems a poor brute
force method. I did not suggest using the breaker in this manner, and
agree it would fail under those conditions.
What would make more sense to me is having the on/off controller monitor
the throttle, when it goes up or the brakes go on, if the current
doesn't drop it THEN can shutdown the power.
I note that using a contactor to disconnect constantly prevents regen.
I do expect to see 1000amps draw during runs, and if that blows out a
contactor it isn't going to be big enough. Sw200 info says 250amp
continuous, 340amp intermittent.
The surplus breakers may not be big enough either.
Jack
Cor van de Water wrote:
As others have pointed out: breakers wear out fast.
Once you start using a breaker as contactor, it is
no more reliable than a contactor - if the contactor
welds shut due to accidental switching under load, so
will a breaker in the same operation.
This defeats the whole purpose.
The SW200 is plenty for all but racing EVs.
Note that the max rating is usually the continuous
rating and no EV should draw more than 360A continuous
or else it will have a disappointing range and you
better find what sucks up all your energy.
My truck at freeway speeds draws 55A (60 MPH constant),
so I am not worried about the 100A max continuous
ON/OFF switch that was mounted in the battery box by
the conversion company US Electricar.
You can look in the archives, but I recall at least 6 or so
stories of different people with a runaway EV in the last
year, that is why it is good to have an additional safety
to kill the motor, in addition to the normal contactor that
is your first line of safety, but due to its daily operation
can weld shut in case of an error in your system. You do
not want to be left without safety due to the error in your
car, because the error can be the runaway situation.
Having a separate contactor and breaker means that the
breaker just sits there, waiting for either an over-current
situation or you pulling the wire to throw it OFF, so it
will never weld shut as it is never switched ON under load.
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
Take your network further http://www.proxim.com
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Jack Murray
Sent: Tuesday, January 02, 2007 7:09 PM
To: [email protected]
Subject: Re: Circuit Breaker and Contactor
yes indeed I am eliminating the contactor by using electromechanics to
turn on/off the breaker. This is basically moving the precharge safety
check out of the controller itself and putting it in the on/off switch.
I'll have a microprocessor which gets an on/off signal (from the key
switch), and it does the automated checking, it turns on the precharge
and confirms there is not a short or load before it turns on the
breaker, perhaps turn on some leds to indicate stop, precharge, go.
It seems to me the breaker should never weld shut, it is designed
specifically not to fail in that way, otherwise, its value as a safety
device is rather diminished. A second breaker could be used for a
backup manual emergency off switch.
I've looked at the contactors available at evparts.com, and the SW200
just doesn't seem big enough with 360amps max, the SW201 at 450amps
seems OK, but it is $255, that seems rather expensive if it can be
eliminated, and it consumes 12v power while on (how much?) Of course
the electromechanics to turn on/off the breaker add cost, but its
something I can build. And using the surplus $30 breakers, the setup
would end up rather inexpensive as I see it.
Jack
Cor van de Water wrote:
Hi Jack,
You are trying to re-design a contactor with built-in breaker?
Note that the functions of breaker and contactor are quite
different, the contactor being an electrically controllable
HV switch and the breaker being an automatic safety disconnect
in case of overload, to protect wiring and other circuitry
from destruction.
I know several EV'ers who strung a wire through the breaker's
handle eyelet, so from the dashboard you could open the breaker
manually as an added security feature.
The issue not yet addressed is the safety that is provided
by using a combination of contactors and pre-charge, which can
be used by your controller to avoid runaway conditions:
1. Before even closing any contactors, the controller can sense
is there is HV on its input, which would indicate a welded
contact, so the controller can refuse to start the motor, as
it has no backup to break the current.
(This can be mildly annoying if your controller is prone to
faulting out or shutting the motor control off before the
contactors drop, so the capacitors will stay charged for
a while - I must wait 30 sec before I can re-start my EV)
2. After pre-charge contactor closing, the controller senses
the voltage to see if it rises high enough to indicate the
HV bus is not unexpectedly loaded, which can indicate one
of the power components has failed. This will avoid a high
current when the main contactor is closed, so it should
never weld shut, allowing it to break in emergencies.
3. Controller *could* include a crow-bar feature, which will
deliberately short-circuit the HV bus and rely on blowing
the breaker or fuse open, if it detects a serious failure,
such as a continuing current draw even after the contactor
was dropped (indicating a weld-shut and runaway).
Note that all these require the use of sensing and deciding
to take a next step, which is best automated. It is possible
to do this manually (as with a breaker) but it would be very
prone to operator faults, you would need a kind of
"pre-flight inspection list" to do the same as most modern
controllers provide built-in.
THe risk is that the driver will learn that simply throwing
the breaker makes the car go, without going through the
safety list, so better automate it, even if it occasionally
can be annoying to see a fault detected - better avoid
driving than encountering a runaway...
Just my 2 contactor's worth,
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
Take your network further http://www.proxim.com
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Jack Murray
Sent: Sunday, December 31, 2006 10:21 AM
To: [email protected]
Subject: Circuit Breaker and Contactor
I've been looking at contactors, fuses, and circuit breakers, and had
the idea of using a circuit breaker as a contactor by creating a setup
that can switch the breaker on and off. This would eliminate the
contactor as well as reduce the continuous power draw of the coil to it.
I'm surprised this hasn't been done before or is offered as a product,
so there must be some downside to it.
It would turn on-off much slower than a contactor, so my guess is that
might be an issue in general, but for a car, I don't see that as a
problem.
In fact, I see a combination of a power-turn-on device that does a
pre-charge to the controller and once complete will turn on the breaker.
The breaker will still break if over-current, but then can be turned off
electrically.
Is there some issue I'm missing?
Thanks,
Jack
--- End Message ---
--- Begin Message ---
Nick Viera wrote:
> I think one very important thing to understand about DC motor
> controllers used in hobbyist EV conversions is that while some
> were designed explicitly for on-road EV use (i.e. Zilla,
> Raptor/T-Rex) many DC controllers used over the years were
> *never* designed for or intended to be used in this application
> (i.e. Curtis *, GE EV-1).
> Perhaps a more realistic statement would be "I find it
> interesting that a DC motor controller **used out of its
> intended application** is so unsafe that it must be
> completely disabled every time you release the go pedal."
I don't think that this is actually as important as you make it out to
be. For instance, while the Curtis may (or may not) have been designed
for or intended for on-road use, it is designed and intended to be wired
such that the potbox microswitch disables it every time one's foot is
removed from the throttle. That is, this is not a safety feature that
we on-roaders have invented or added on as a bandaid to restore safety
due to our mis-application of the product.
Likewise, although the GE EV-1 is an older design and uses old
technology, it has *more* built in safety features than a modern Curtis
series motor controller. For instance, the logic checks that the main
SCR has turned off each time it is supposed to (i.e. every single
switching cycle), and if it is ever found to be on when it isn't
supposed to be, the logic will drop out the main contactor. Similarly,
the controller includes logic to control a bypass contactor, and it will
only pull in the bypass when certain conditions are met, and will drop
it out if other conditions are met (e.g. overcurrent); it checks to
confirm that the bypass has opened, and if it hasn't, the controller
drops out the main contactor. In fact, the first thing the logic does
when the controller powers up is to test the commutating capacitors to
ensure that they are going to be capable of turning off the main SCR; if
they are found lacking, it will lock itself out so that the main SCR
cannot be turned on. Despite all of this, it also is designed and
intended to be wired such that the main contactor (FWD/REV contactors in
lift truck applications) open each time the throttle is released (or the
driver leaves the seat, etc.).
The Zilla has the distinction of having the reputation for being about
the most reliable series motor controller in on-road use, but every
other modern series controller make (e.g. Curtis, DCP, Auburn, etc.) has
certainly experienced failures though I have no way of knowing how many
have been of the run-away type.
Some time (years?) ago, Bill Dube described an interesting "failure"
mode with his modern controller (Auburn?): I think he described it as a
"walk away". Basically, the controller was fine, but the throttle did
not return completely to the off position for some reason, and this
modern controller had sufficient current multiplication that the motor
torque was so great that Bill could not stop the car even standing on
the brakes. Since there was no fault condition (the controller cannot
know if you meant to creep forward or not), the system did not shut down
on its own, and stopping the car was only possible because Bill had
provided some manual means of interrupting traction power.
With the possible exception of the Zilla (due to its proven reputation
for reliability), I would suspect that there is a very real possibility
that controllers designed for on-road use are likely to be *less* safe
simply because they tend to be designed by small companies (often just
one or two individuals) and may omit features that are present in
industrial controllers because they are deemed unnecessary, or even
simply because these designers aren't aware of them. It isn't that
these designers are any less skilled than the designers of the
industrial controls, but rather than the industrial designers have the
benefit of *years* of experience designing traction controls, and of
having *thousands* of units in the field in all sorts of applications.
Over time they will have seen a variety of failure modes and will have
refined their designs to protect against them. Without the benefit of
such experience, designers of on-road controls might not appreciate the
value/benefit of a feature (e.g. opening the contactor each time the
throttle is released), and will not include it in their design (for
instance because the clack/clack is deemed annoying, etc.).
Finally, bear in mind that despite the impressive reliability of the
Zilla controller, and the fact that it includes a microprocessor (the
hairball) whose main responsibility seems to be keeping an eye on the
contactors and ensuring they turn on and off only when appropriate
(which is apparently deemed adequate to eliminate the need to open a
main contactor each time the throttle is released), the 'key' input line
is still designed to provide a means of manually removing power from the
main contactor in the event of the unthinkable.
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
People are winding their own generators with rare earth magnets for home
windmills. (And the process is lowcost and plans are easily available on
the net.
Why couldn't he same be done for a wheel for a conversion for an ev'er?
Make the wheel hub the actuall armature of the motor so size is minimal
and bearing are needed for only one axle.
(don't build a small motor into the wheel.
Instead put a tire on the outside of the large radius homebuilt motor).
On Thu, 4 Jan 2007 2:54 pm, Tom Shay wrote:
This might be a great way to build an EV if suitable motor-wheel
assemblies were available at reasonable prices. But they aren't
available. Motors built into the wheel hub are available for
bicycles and some are brushless and gearless. Maybe someday hub
motors for a VW sized vehicle will be available but not yet.
----- Original Message ----- From: "Jonathan Perret" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Thursday, January 04, 2007 7:43 AM
Subject: direct drive (basic questions)
I'm curious to understand how much work is involved in
converting an ICE car (VW Beetle for instance) into an electric vehicle
that has the wheeels driven directly by motors on each wheel
rather than via the existing transaxle...
for example how do you mate the motor shaft to the wheel hubs for say
the front wheels which previously (as an ICE car) weren't driven, just
rolled.
thanks,
Jonathan
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 ---
An update so this may slip into the archive properly "closed" (and
potentially useful to searchers in the future)...
Roger Stockton looked at the schematic for this controller in the Club
Car application (link in earlier message) and determined that a standard
off-the-shelf potentiometer will work in place of the Club Car's 5-wire
proprietary unit.
Here's what he suggested, which I tried last evening. Happy to report
the 1204-410 does work with this setup (which means I now have two
different low end controllers to play with in the Joe Sixpack Geo -
thanks Roger) ...
From the diagram, connect (terminal #s per the diagram you linked to):
- pack +ve via the keyswitch, etc. to terminal #1 on the controller.
This is the controller "KSI" input, and is what enables/powers up the
> logic. You must have the pot connected and set to
a resistance corresponding to 0 speed before applying power to this
connection.
- the pot wiper connects to terminal #2 on the controller.
- one end of the pot (the wide-open throttle end, I believe) connects to
terminal #3 on the controller.
- the other end of the pot (the idle end, I believe) connects to pack
-ve. This connection is usually not present on a Curtis installation,
but perhaps it is required by the Club Car controller flavour.
It is possible that the CC controller uses a 5k-0 pot; the Curtis is
available configured for either 0-5k or 5k-0, and may also be available
in a flavour that accepts a voltage input (which could explain the pack
-ve connection to one end of the pot in the CC diagram).
The only difference I noted in trying this is that this controller
doesn't have the high-pedal lockout feature.
Darin
--- End Message ---
--- Begin Message ---
Jack wrote -
>I find it interesting that a DC motor controller is so unsafe that it
> must be completely disabled every time you release the go pedal. That
> really says something.
You are the only one that has said that controllers are "unsafe",
And nobody has said that they are "so unsafe" that when the accelerator is in
the unpushed position, that the contactor HAS to be in the off position
For me, and many others on this list, it is just a safety precaution... Since
the motor is not being used for propulsion, there is no reason why the power to
the controller can not be turned off.
Here is an email from Lee Hart on the subject -
----- Original Message -----
From: "Lee Hart"
To: <[email protected]>
Sent: Saturday, December 17, 2005 12:16 PM
Subject: Re: Failure Modes (was Re: Motor control for direct drive setup)
> Steve Clunn wrote:
>>> I can remember thinking, "My this car has good pick up even
>>> with me pushing as hard as I can on the brakes!"
>
> Bob Rice wrote:
>>> And STANDING on the brakes to ease it into a telephone pole to STOP
>>> it and amid tire smoke trying and disconnecting the nearest power
>>> cable! Wow! What A fireball when I did! Don't try this at home!
>
> Nick Viera wrote:
>> Reading stuff like this is disconcerting and makes me want to know more
>> about the specifics of the systems involved and why there was no way to
>> cut power immediately (or if there was, why/how it failed).
>
> Beginners tend to assume that things will never go wrong. They leave out
> fuses
> or circuit breakers, use undersized contactors, and take other short cuts to
> save money. Obviously, this is OK when everything works.
>
> The trouble begins when something goes wrong. And with electric motors, they
> are as likely to fail FULL THROTTLE as they are off! There are many tragic
> examples of what can happen if a car fails "full throttle" and the driver
> can't react fast enough or remember what to do to stop it.
>
>> My Jeep still doesn't have a manual mechanical disconnect in the High
>> Voltage system, but I do have a clutch.
>
> But if the controller fails, will you remember to push the clutch? Would your
> wife?
>
>> I'd like to know is if it is reasonable to assume that a full-on
>> controller failure situation could be stopped safely through the use
>> of the main contactors (even if it blows the crap out of them)?
>
> If you size the contactors so they are barely big enough to handle the normal
> load current, they may be too small to reliably open in case of a worst-case
> fault.
>
> Contactors have several sets of voltage and current ratings; continuous duty,
> short-term (like for 5 minutes), and one-time emergency disconnect. For
> example, the Albright SW200 with magnetic blowouts is rated:
>
> 96vdc at 250 amps continuous
> 450 amps for 5 minutes
> 1000 amps for 1 minute
> 1500 amps maximum one-time
>
> If you use flooded batteries, their short-circuit current is probably less
> than 1500 amps; thus this contactor could safely break even a dead short. But
> if you use high-performance AGMs, their short circuit current could easily be
> 2000-3000 amps; this contactor could fail "on" if asked to break such a load!
>
> Fuses and circuit breakers are usually a better choice for reliably breaking
> high currents. It's not uncommon for them to be able to safely break even
> 10,000 amps. They also operate automatically, and so don't depend on some
> external circuit to tell them when to turn off. You normally size them at
> around 200% of your normal current; if your EV draws 100 battery amps
> steady-state, you would use a 200 amp fuse or circuit breaker.
>
> But of course a fuse or circuit breaker won't automatically trip unless the
> current is well above normal. If you're driving at 60 mph when the controller
> fails, the motor keeps right on drawing 100 amps. If you slam on the brakes
> and drag the car down to 30 mph, the motor current may rise to 300 amps but
> it just keeps right on pulling. A 200amp fuse or breaker at 300amps may take
> up to a minute to finally open. That's going to be the most exciting minute
> of your life!
>
> The safest setup is to use a switch on the accellerator pedal that turns off
> the main contactor when you release it. This is the first thing the driver
> will do. The contactor won't wear out early; they are built for hundreds of
> thousands of operations like this.
>
> But some people object to the "click-clack" every time you press and release
> the accellerator. An alternative that's almost as good is to put a switch on
> the brake pedal that drops the contactor each time you step on the brakes.
> That's the second thing a driver is likely to do in an emergency.
>
> Finally, you can wire the contactors through the keyswitch, so they turn off
> if you turn off the key. This works, but is not as good because it may take a
> driver a long time to think of turning off the key. And if he does, there is
> a risk of locking the steering wheel as well!
>
> There are some automated methods as well. The Zilla controllers sense a
> controller failure, and drop the contactors for you. John Wayland worked out
> a way to wire the contactor to turn off if the accellerator switch turns off
> and the controller is still on.
>
> The "runaway failure mode" is easy to deal with. You just have to be aware
> that it exists, and wire things to prevent it!
> --
> Lee A. Hart 814 8th Ave N Sartell MN 56377
Hope this helps,
Rush
Tucson AZ
www.ironandwood.org
www.Airphibian.com
--- End Message ---
--- Begin Message ---
Jack Murray wrote:
> I do expect to see 1000amps draw during runs, and if that blows
> out a contactor it isn't going to be big enough. Sw200 info
> says 250amp continuous, 340amp intermittent.
The SW200 will survive higher currents; Otmar uses them in his EV (and
has used both his Z1K and Z2K controllers in there, I believe). Rod
Wilde has used them in the Maniac Mazda... at just a "bit" ;^> more than
1000A.
Kilovac's offerings may be a better choice if you want something rated
to safely interrupt the voltage and currents present in your system in
the event of a fault, but the attraction of the Albright is that you can
inspect the contacts for wear and inexpensively replace the contacts as
required.
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
The industrial permanent magnet AC servos have fixed torque over
1:10000 RPM range, with appropriate FOC control algorithms. These are
used for industrial robot arms for instance.
I believe people have gotten very good fixed torque ranges with modern
control algorithms out of squirrel-cage AC motors as well, but the
mass-produced "inverter rated" ones that i know of are not designed
for low weight.
Even Tesla had to use a gearbox to go at speeds appropriate for a Roadster :)
-kert
On 1/4/07, GWMobile <[EMAIL PROTECTED]> wrote:
People are winding their own generators with rare earth magnets for home
windmills. (And the process is lowcost and plans are easily available on
the net.
Why couldn't he same be done for a wheel for a conversion for an ev'er?
Make the wheel hub the actuall armature of the motor so size is minimal
and bearing are needed for only one axle.
(don't build a small motor into the wheel.
Instead put a tire on the outside of the large radius homebuilt motor).
On Thu, 4 Jan 2007 2:54 pm, Tom Shay wrote:
> This might be a great way to build an EV if suitable motor-wheel
> assemblies were available at reasonable prices. But they aren't
> available. Motors built into the wheel hub are available for
> bicycles and some are brushless and gearless. Maybe someday hub
> motors for a VW sized vehicle will be available but not yet.
> ----- Original Message ----- From: "Jonathan Perret" <[EMAIL PROTECTED]>
> To: <[email protected]>
> Sent: Thursday, January 04, 2007 7:43 AM
> Subject: direct drive (basic questions)
>
>
>> I'm curious to understand how much work is involved in
>> converting an ICE car (VW Beetle for instance) into an electric vehicle
>> that has the wheeels driven directly by motors on each wheel
>> rather than via the existing transaxle...
>>
>> for example how do you mate the motor shaft to the wheel hubs for say
>> the front wheels which previously (as an ICE car) weren't driven, just
>> rolled.
>>
>> thanks,
>>
>> Jonathan
>>
>>
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 ---
There is an important point here.
The value of having an electric will continue to rise as gas and all
other materials demanding by the growing behemoth china continue to
dwarf any rises in the past.
And when those cost have risen so will the cost of converting an
electric.
We know lead and copper and gas and things will rise in price. Therefore
justify your conversion not on todays savings but on tomorrows and the
savings on the cost of converting tomorrow.
Also an electric car gives you independence in a catatrope if you have
some self generation capacity. Even minor self generation capicity
allowing you to recharge totally only every 3 or for days means you can
hit the road when others can't if an iran war causes gas to be limited
like during the 70's.
.
On Thu, 4 Jan 2007 12:59 pm, Cor van de Water wrote:
Hi Bob,
No - controllers in parallel don't play nice, unless they are
designed to do so, but I have not seen any that have a
master/slave or synchronisation control to fire at the same time.
All battery prices have been raised last year due to the
price of raw lead going through the roof...
My supplier sent me a nice reminder before raising prices, so
I was warned in case I were ready to buy - at the old price.
No new battery purchase planned here, but I forwarded the
warnings to the list, in case others were ready and would like
to avoid the price hike.
Soon our batteries will be more valuable than when we bought
them ;-) - invest in a lead sled now - grin.
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
Take your network further http://www.proxim.com
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Bob Rice
Sent: Thursday, January 04, 2007 8:12 AM
To: [email protected]
Subject: New Sentra , WAS new EV business
Hi EVerybody;
Stealing the thread here, as I have a EVer growing yard full of EV
wannabees. Looking for a bit of feedback on doing a 97 Sentra, which I
have
a clean example in the garage. I'm fitting it with a Warp 9" Impulse
motor,
the shortened 9" job.Was thinking of a 72 volt system with Alltrax'es
BIGGEST 450 amp controller. I don't want to make a Lead Sled out of it,
or a
tire schorcher. Somewhere in between? 72 volts on a 9" motor it should
be
able to loaf along, limited only by the Alltrax amps. By using all the
gears
all the time, It should be able to keep up with off- Turnpike traffic?
Alltrax controllers are a here now, thing, call then and it's a "
How
many would ya like?" thing. He, Steve, there said that guyz are going
with
TWO motors and controllers, for 900 amps, enoughh to break any
battery's
back!Anybody here doing this?Could you hook two Alltrax up to the same
motor
for more amps, like I guess paralleling them? Would they play well
together,
fed the same signals from two pots?Or one?This would be cheaper1000k or
so
than a Curset or Zilla.
OK Sports fans; Slipping inyto my flame proof suit, what do ya
think? A
72 volt Sentra, as above?Only 12 batteri, at replacement time, sounds
good.
Gees! I was quoted about 80 bux for a T-105 equivelent. Batterey prices
are
going through the roof! Anybody gotten any at Sam's Klub for 40,
lately??
Seeya at BBB?
Bob
----- Original Message -----
From: "Roger Stockton" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Wednesday, January 03, 2007 8:55 PM
Subject: RE: new EV business
Gary wrote:
SNIP
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 ---
Because recyclers can choose to sell the recylced lead on the open
market rather than stick it back into batteries.
On Thu, 4 Jan 2007 12:59 pm, Don wrote:
RE: Battery price hike. It's been said that car batteries are the most
successfully recycled item to date. How can the price of lead (if
recycled)
affect the cost of batteries? Inflation is inevitable, but....
Don Davidson
[EMAIL PROTECTED]
www.elecars.spaces.live.com
----- Original Message -----
From: "Cor van de Water" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Thursday, January 04, 2007 12:36 PM
Subject: RE: New Sentra , WAS new EV business
Hi Bob,
No - controllers in parallel don't play nice, unless they are
designed to do so, but I have not seen any that have a
master/slave or synchronisation control to fire at the same time.
All battery prices have been raised last year due to the
price of raw lead going through the roof...
My supplier sent me a nice reminder before raising prices, so
I was warned in case I were ready to buy - at the old price.
No new battery purchase planned here, but I forwarded the
warnings to the list, in case others were ready and would like
to avoid the price hike.
Soon our batteries will be more valuable than when we bought
them ;-) - invest in a lead sled now - grin.
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
Take your network further http://www.proxim.com
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Bob Rice
Sent: Thursday, January 04, 2007 8:12 AM
To: [email protected]
Subject: New Sentra , WAS new EV business
Hi EVerybody;
Stealing the thread here, as I have a EVer growing yard full of EV
wannabees. Looking for a bit of feedback on doing a 97 Sentra, which I
have
a clean example in the garage. I'm fitting it with a Warp 9" Impulse
motor,
the shortened 9" job.Was thinking of a 72 volt system with Alltrax'es
BIGGEST 450 amp controller. I don't want to make a Lead Sled out of
it, or
a
tire schorcher. Somewhere in between? 72 volts on a 9" motor it
should be
able to loaf along, limited only by the Alltrax amps. By using all the
gears
all the time, It should be able to keep up with off- Turnpike traffic?
Alltrax controllers are a here now, thing, call then and it's a "
How
many would ya like?" thing. He, Steve, there said that guyz are going
with
TWO motors and controllers, for 900 amps, enoughh to break any
battery's
back!Anybody here doing this?Could you hook two Alltrax up to the same
motor
for more amps, like I guess paralleling them? Would they play well
together,
fed the same signals from two pots?Or one?This would be cheaper1000k
or so
than a Curset or Zilla.
OK Sports fans; Slipping inyto my flame proof suit, what do ya
think? A
72 volt Sentra, as above?Only 12 batteri, at replacement time, sounds
good.
Gees! I was quoted about 80 bux for a T-105 equivelent. Batterey
prices
are
going through the roof! Anybody gotten any at Sam's Klub for 40,
lately??
Seeya at BBB?
Bob
----- Original Message -----
From: "Roger Stockton" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Wednesday, January 03, 2007 8:55 PM
Subject: RE: new EV business
> Gary wrote:
SNIP
>
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 ---
Which of course is exactly the idea I proposed before.
How the hell did someone patent that?
On Thu, 4 Jan 2007 1:38 pm, Jack Murray wrote:
A way to acheive this is to have an outer ring gear and multiple
smaller motors that drive the ring gear, and thus you can gear them to
get the torque needed and have room because they are small motors on
the perimeter of the axle.
So you attach this to the axle which is fixed to not move, and the
wheel bolts to the ring gear. Jack's patent number
8287732332343234432234
Available in 2008 for $2,500 each, only $10,000 per car, three wheelers
get a 25% off sale. :)
And btw, I recall a guy in the AZ desert built a gas powered version of
this, where the ring gear was inverted and essentially acted as
pistons, simpler but similiar to a radial motor without a crankshaft
which I believe was his inspiration.
Jack
Peter VanDerWal wrote:
The hard part isn't mating the motor to the wheels, the hard part is
finding a motor that will work.
This application requires a low RPM motor with HUGE torque. I'm not
aware
of anyone that sells a motor like this for less than $10,000 a pop (not
including controller)
If you are going to be spending that much money, you might as well go
with
an NGM wheel motor (motor is inside the wheel). It's only a little bit
more expensive.
I'm curious to understand how much work is involved in
converting an ICE car (VW Beetle for instance) into an electric vehicle
that has the wheeels driven directly by motors on each wheel
rather than via the existing transaxle...
for example how do you mate the motor shaft to the wheel hubs for say
the
front wheels which previously (as an ICE car) weren't driven, just
rolled.
thanks,
Jonathan
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 ---
>I find it interesting that a DC motor controller is so unsafe that
>it must be completely disabled every time you release the go
>pedal. That really says something.
It is prudent to have two ways of shutting off a safety-critical device. In
a power supply, the primary way is turning off the MOSFET, the secondary way
(in the case of a MOSFET short) is a power fuse that will blow quickly. In a
'standard' DC motor drive, a single point failure (MOSFET) will almost
always result in a short circuit, and a stuck on motor, and releasing your
foot does not cause it to turn off. Any prudent design engineer would build
in some kind of redundancy.
To EV's, I'm pretty new (worked with a couple AC systems about 12 years
ago), but I design electronic engine controllers as my day job - mostly for
use on natural-gas powered busses. They are almost all throttle-by-wire.
This is a quick view of the safety logic built in to most (perhaps all)
throttle-by-wire ICE systems:
There is a switch on the accelerator pedal that acts as a redundant signal
to the engine controller so that an accelerator pedal potentiometer fault
can be sensed. An addition, brake and clutch switch inputs are used to
determine if the driver does not desire engine power now. These are natural
responses to the driver, so they are used in logic to determine whether the
accelerator signal is valid. Note that cruise control and other features
make things more complicated but not by much.
On the engine, intake manifold pressure is compared to the commanded value,
and two throttle position sensors report the controlled throttle motor
position. If any of those don't make sense, the vehicle enters some sort of
limp-home mode if possible. If the throttle is stuck open, no limp mode is
possible and the vehicle is turned off by disabling fuel delivery. Note that
the safety is there if a fault is detected, but stays out of the way when
things are normal. This sort of safety system undergoes extensive safety
testing, and we have a procedure where another person tests the systems
independantly of me (the designer and programmer). On an ICE, you can't
activate the redundant shutoff (the engine would stall instead of idle)
unless you really mean it.
This being said, a fully integrated safety system would include logic to
disable the contactor if the commanded accelerator pedal position is zero -
or the brake is on - AND motor current is not what is commanded for more
than maybe 1/4 second or so. Then the main contactor drops. Otherwise, the
contactor doesn't cycle with accelerator pedal motion. Any system like that
requires extensive testing.
An AC drive is 'better' in this regard. A fast vehicle acceleration does not
occur, and a safe controller should detect a shorted IGBT and turn off all
of the other devices, causing the motor to freewheel. This falls apart if
multiple IGBT's blow at once, but so does it if the crankshaft flys out of
an ICE, or a driveshaft falls off - the brakes can lock up. Saw it on a dyno
once. Twisted off the dyno shaft. I was at the controls, but it went by so
fast that I didn't have time to hit the E-stop.
As for using a breaker in place of a contactor, it has been done but you
must precharge the controllers (especially capacitors) before turning it on.
Some AC controllers can accept power all of the time and have either
contactors or other safety circuitry built in, and on those vehicles I have
seen no-contactor electrical systems. Some breakers also have an emergency
'trip' solenoid that will trip them, which you could use as a safety
shutdown, but you'd really need to test this out well. But you must
precharge before closing a breaker because the contacts will not last past
maybe 50 closures. I've seen that on one of those vehicles that I have
worked on in the past.
-Dale Ulan
Calgary, Canada
--- End Message ---
