EV Digest 6273
Topics covered in this issue include:
1) Re: New Sentra , WAS new EV business
by "Phil Marino" <[EMAIL PROTECTED]>
2) Re: Unsafe Controllers
by "Michaela Merz" <[EMAIL PROTECTED]>
3) Re: direct drive (basic questions)
by "Chris" <[EMAIL PROTECTED]>
4) Re: Circuit Breaker and Contactor
by "Chris" <[EMAIL PROTECTED]>
5) Re: Surplus Capacitors - Was: Joe Sixpack Geo: best controller...
by Danny Miller <[EMAIL PROTECTED]>
6) Motor shaft taper
by [EMAIL PROTECTED]
7) Unsafe Controllers
by Bill & Nancy <[EMAIL PROTECTED]>
8) Re: Unsafe Controllers
by "Phil Marino" <[EMAIL PROTECTED]>
9) RE: Unsafe Controllers - Question ...
by "Michaela Merz" <[EMAIL PROTECTED]>
10) RE: Surplus Capacitors - Was: Joe Sixpack Geo: best controller...
by "Myles Twete" <[EMAIL PROTECTED]>
11) RE: Unsafe Controllers - Question ...
by "Roger Stockton" <[EMAIL PROTECTED]>
12) RE: Unsafe Controllers - Question ...
by Ray Wong <[EMAIL PROTECTED]>
13) Brake motor current switch (was: Unsafe Controllers - Question
...)
by Bill Dube <[EMAIL PROTECTED]>
14) Re: Circuit Breaker and Contactor
by Lee Hart <[EMAIL PROTECTED]>
15) Re: Unsafe Controllers - Question ...
by Lee Hart <[EMAIL PROTECTED]>
16) Re: Surplus Capacitors - Was: Joe Sixpack Geo: best controller...
by Lee Hart <[EMAIL PROTECTED]>
17) Re: Unsafe Controllers
by Lee Hart <[EMAIL PROTECTED]>
18) RE: Unsafe Controllers
by "Roger Stockton" <[EMAIL PROTECTED]>
19) Re: Unsafe Controllers - Question ...
by "Chris" <[EMAIL PROTECTED]>
20) RE: Unsafe Controllers - Question ...
by Cor van de Water <[EMAIL PROTECTED]>
21) KillaCycle web site - Updated (finally)
by Bill Dube <[EMAIL PROTECTED]>
22) RE: Surplus Capacitors - Was: Joe Sixpack Geo: best controller...
by Cor van de Water <[EMAIL PROTECTED]>
23) RE: Unsafe Controllers - Question ...
by Cor van de Water <[EMAIL PROTECTED]>
--- Begin Message ---
From: GWMobile <[EMAIL PROTECTED]>
Reply-To: [email protected]
To: [email protected]
CC: [EMAIL PROTECTED]
Subject: Re: New Sentra , WAS new EV business
Date: Thu, 4 Jan 2007 15:03:41 -0500
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.
This last point is only true if you have the capability to generate power
from sources other than gasoline - or diesil-powered generators. If you
have your own solar or wind-generation, then you, indeed, have some
independence from rising fossil fuel prices and reduced availability.
Phil
_________________________________________________________________
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--- End Message ---
--- Begin Message ---
> Jack Murray 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.
Lee Hart wrote:
> It's not that a controller is unsafe; it's just that the consequences of
> a failure can be very bad. Therefore, good design practice requires that
> you do things to make it fail "safe" (i.e. off, not on).
I respectfully disagree ;) If an electronic device like a controller
offers the remote possibility that a failure might end up in loss of life
(or injury, property damage) it should have to be redesigned to address
those issues. If necessary with an second, even external electronic
circuit that monitors the controller and cuts power if something smells
wrong (sort of a watchdog circuit).
I always have my foot on the clutch and put my car in neutral while
stopped whenever driving in city traffic. Not a good feeling. One of the
many flaws of old-fashioned DC technology.
Michaela (now hiding under the desk waitin' for the flames)
--- End Message ---
--- Begin Message ---
Hey Tom, wheel motors are available, if a little bit expensive.
a 5kW wheel motor costs abotu £1500, and a controller to drive it
about £2500, from PML flightlink
http://www.pmlflightlink.com/
But this is just their bottom end....go higher up in price and they
have wheel motors over 100kW with all drive and control electronics
built in.
If they were a tad cheaper I would be straight in.
Chris
--- In [EMAIL PROTECTED], "Tom Shay" <[EMAIL PROTECTED]> 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
> >
> >
>
--- End Message ---
--- Begin Message ---
There's something to be said for the old crowbar.....a contactor to
short the battery in case of runaway, which would blow your main fuse
_as long as you fit the fuse the right side of the crowbar_ !
--- In [EMAIL PROTECTED], Jack Murray <[EMAIL PROTECTED]> wrote:
>
> 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 ---
Farad-volt is a meaningless number because energy storage goes up with
the SQUARE of voltage. So a 1F 20V cap has twice the capacity of a 2F
10V. You need to use farad-volt^2, or more logically use the
conventional unit of Joules. Joules of energy is (capacitance*voltage^2)/2.
Danny
Bruce wrote:
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 ---
Can anyone tell me where to find the engineering specs of the taper on the
end of a GE motor. I am told the motor is 36V 4HP, looks like a typical golf
cart motor to me ?
Anyhow the output shaft has a keyed taper on it, with a helical gear fitted
to it. i want to fit a chain sprocket but need the taper spec before I start
ordering bits.
TIA
Chris
--- End Message ---
--- Begin Message ---
The discussion about using safety switches for your contactor is
appreciated. I am in the process of wiring my EV project now and was
going to ignore the safety micro on the throttle pot, but will hook it up.
Thanks,
Bill
( Bradley GTE with 1221C controller at 120 volts.)
--- End Message ---
--- Begin Message ---
From: "Michaela Merz" <[EMAIL PROTECTED]>
Reply-To: [email protected]
To: [email protected]
Subject: Re: Unsafe Controllers
Date: Thu, 4 Jan 2007 15:14:33 -0600 (CST)
> Jack Murray 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.
Lee Hart wrote:
> It's not that a controller is unsafe; it's just that the consequences of
> a failure can be very bad. Therefore, good design practice requires that
> you do things to make it fail "safe" (i.e. off, not on).
I respectfully disagree ;) If an electronic device like a controller
offers the remote possibility that a failure might end up in loss of life
(or injury, property damage) it should have to be redesigned to address
those issues. If necessary with an second, even external electronic
circuit that monitors the controller and cuts power if something smells
wrong (sort of a watchdog circuit).
I always have my foot on the clutch and put my car in neutral while
stopped whenever driving in city traffic. Not a good feeling. One of the
many flaws of old-fashioned DC technology.
Keeping the motor disengaged from the drive train when stopped sounds like a
good idea. But, if the transmission is in neutral, there's no need to
also keep the clutch disengaged ( pedal down). That could prematurely wear
out your throwout bearing.
And, if you have a setup that opens the main contactor ( either by lifting
your foot off the accelerator or by pressing on the brake pedal) - as you
should - you're already protected against a full-on controller failure while
you're stopped.
Phil
_________________________________________________________________
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--- End Message ---
--- Begin Message ---
Wouldn't it be possible to build a circuit that:
Disables the contractor whenever the brake lights come on AND there is
current (or voltage) on the motor? Wouldn't that clearly indicate the
drivers desire to stop even though there seems to be power delivered to
the motor?
Somebody able to draw up a quick circuit?
Michaela
--- End Message ---
--- Begin Message ---
Danny Miller offered:
> Farad-volt is a meaningless number because energy storage goes up with
> the SQUARE of voltage.
Sure, it's inappropriate, but it is not meaningless---a Farad-Volt is a
Coulomb, the basic unit of charge (Q=C*V), and definitely not meaningless.
> So a 1F 20V cap has twice the capacity of a 2F
> 10V.
You mean twice the stored ENERGY, not twice the capacity.
A 1F cap has 1 Farad of capacity, which is 1/2 that of a 2F cap, regardless
of the voltage rating of the cap or what is actually across the cap.
And if the 1F/20v cap and 2F/10v caps both have 10v applied to them, the 2F
cap wins BOTH on an energy (Joules) AND charge (Coulomb) measure.
Sure, if the 1F/20v cap is charged to 20v, it will have 2x the stored ENERGY
of the 2F cap with only 10v across it---after all, E = 1/2 * C * V^2 as you
point out.
But both would have the same charge (Q) in coulombs and the 2F cap would
still have greater "capacity".
-Myles Twete, Portland, Or.
--- End Message ---
--- Begin Message ---
Michaela Merz wrote:
> Wouldn't it be possible to build a circuit that:
>
> Disables the contractor whenever the brake lights
> come on AND there is current (or voltage) on the
> motor? Wouldn't that clearly indicate the drivers
> desire to stop even though there seems to be power
> delivered to the motor?
>
> Somebody able to draw up a quick circuit?
Yep; this is almost exactly what John Wayland proposed a few years ago.
I think his scheme used the potbox microswitch to detect that the
throttle was released, and if motor current is present at this time, it
would drop out the contactor.
I would not rely on the brake lights being on, but would instead use a
switch actuated by the brake pedal and/or the throttle microswitch so
that the safety system will work even if the brake lights don't ;^>
There should be a circuit in the archives somewhere (though I've never
really been very successful searching them for anything ;^).
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
Although my EV is far from finished, I was planning to add a mini PLC from
Keyence KV-16DR that is slightly larger than my mouse and cost $30 used on
ebay. It has 8 isolated inputs and 8 relay outputs, a visual display, LEDs,
override buttons. AC or 24vDC versions.
http://world.keyence.com/products/program/vkv/vkv.html
With a bit of ladder logic, the stand alone unit can monitor the EV for
faults and safety shutdowns. It even has high speed counters to monitor a
motor rpm sensor and shut down things, over temperature switch such as on an
ADC, etc.
You probably don't need this with a Zilla but it would certainly be a nice
addon to a Curtis to have programmable safety shutdowns that are completely
independent.
Ray
Michaela Merz <[EMAIL PROTECTED]> wrote:
Wouldn't it be possible to build a circuit that:
Disables the contractor whenever the brake lights come on AND there is
current (or voltage) on the motor? Wouldn't that clearly indicate the
drivers desire to stop even though there seems to be power delivered to
the motor?
Somebody able to draw up a quick circuit?
Michaela
__________________________________________________
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--- End Message ---
--- Begin Message ---
John Wayland figured out how to do this very cleverly several years ago.
As I recall John placed a magnetic reed switch right next to the
motor cable so that it would open when current was flowing to the
motor. He put this reed switch in parallel with a brake pedal switch
that would open when the pedal was pressed. This whole thing was
placed in series with the main contactor "seal in" circuit.
If there was a large current flowing to the motor, and you put your
foot on the brake, it would drop out the main contactor.
Quite clever, isn't it?
Bill D.
At 02:42 PM 1/4/2007, you wrote:
Wouldn't it be possible to build a circuit that:
Disables the contractor whenever the brake lights come on AND there is
current (or voltage) on the motor? Wouldn't that clearly indicate the
drivers desire to stop even though there seems to be power delivered to
the motor?
Somebody able to draw up a quick circuit?
Michaela
--- End Message ---
--- Begin Message ---
Chris wrote:
There's something to be said for the old crowbar.....a contactor to
short the battery in case of runaway, which would blow your main fuse
_as long as you fit the fuse the right side of the crowbar_ !
I'm building a solid state relay to control an EV heater. It offers a
small example of how such a system works.
The main switch is an IGBT, rated for about 3x the voltage and current
that the load normally uses.
There is a fuse in series, DC rated for the pack voltage, and with an
I^2T value smaller than that of the IGBT. This means that if the load
shorts, the fault current will blow the fuse before the IGBT fails.
If the IGBT fails "on", you could have a runaway heater that could start
a fire. So, there is also a SPDT relay in series with the fuse and IGBT.
The NO contact powers the heater. The NC contact *shorts* the heater
through a resistor that draws several times the fuse's rated current.
This NC contact is a "crowbar" circuit. If the IGBT is ever on when the
relay is off, it blows the fuse.
Normally, when you turn the heater on, the relay pulls in. A feedback
circuit verifies that the relay pulled in; this enables the temperature
control circuit.
The temperature control circuit measures temperature with a thermistor,
and cycles the IGBT on/off as needed to control temperature. The relay
remains on throughout this time. There are several safety circuits; the
IGBT and relay are turned off:
- if the heater temperature is too high
- if the IGBT heatsink is too hot
- if the wires to the thermistor are shorted or open
- if the temperature controller fails to cycle within 3 minutes
(for example, thermistor is connected but fell off the heater)
When you turn off the heater, it turns off the IGBT, then turns off the
relay.
The whole point of all this extra "stuff" is so that any failures I can
imagine will turn off the heater and/or blow the fuse so it can't be
used until it is fixed.
--
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 ---
Michaela Merz wrote:
Wouldn't it be possible to build a circuit that:
Disables the contractor whenever the brake lights come on AND there is
current (or voltage) on the motor? Wouldn't that clearly indicate the
drivers desire to stop even though there seems to be power delivered to
the motor?
My own EV is currently wired this way. When you step on the brake pedal
and it turns on the brake lights, it also drops the main contactor.
--
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 ---
Bruce wrote:
Both of those surplus places had interesting web sites.
For controller input filtering, don't buy based on microfarads; buy
based on ripple current and ESR rating. This will be harder, because
you'll have to do some research to find out each capacitor's ripple
current rating.
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
Probably less than 1 amp each.
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
This is probably a better part for the application.
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
These are worthless here; far too low a current and too high an ESR.
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
(I corrected the url). This is the most promising. The screw terminals
imply a high ripple current and low ESR rating.
And they also have 430mF - 125VAC Mallory caps for $6 each.
That's only $0.11 per Farad-Volt.
http://www.excesssolutions.com/cgi-bin/item/ES2353
This is worthless for your application. It is a motor starting
capacitor, only used for a second or so at a time. It has a high ripple
current rating, but bad ESR and will have an extremely short life.
--
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 Hart wrote:
It's not that a controller is unsafe; it's just that the consequences
of a failure can be very bad. Therefore, good design practice
requires that you do things to make it fail "safe" (i.e. off, not on).
Michaela Merz wrote:
I respectfully disagree ;) If an electronic device like a controller
offers the remote possibility that a failure might end up in loss
of life (or injury, property damage) it should have to be redesigned
to address those issues.
What do you disagree with? It sounds like you're saying the same thing I
did -- that you design out the dangerous failure modes.
If necessary with an second, even external electronic circuit that
monitors the controller and cuts power if something smells wrong
(sort of a watchdog circuit).
Yes; that is exactly what the external contactor and its control
circuitry is for. If the main controller ever fails "on", then this
backup system insures that it can still be turned off.
I always have my foot on the clutch and put my car in neutral while
stopped whenever driving in city traffic. Not a good feeling. One
of the many flaws of old-fashioned DC technology.
This is a manual backup method. What form of automatic safety shutdown
does your EV have on its own? I.e. if your controller fails "on", what
stops it if you DON'T press the clutch and put it in neutral?
--
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 ---
Michaela Merz wrote:
> I always have my foot on the clutch and put my car in
> neutral while stopped whenever driving in city traffic.
> Not a good feeling. One of the many flaws of
> old-fashioned DC technology.
This has little to do with 'old-fashioned' DC technology and more to do
with how well or poorly your controller has been designed and/or
installed.
If you are using a Curtis, and it is wired properly so that the
contactor opens when the throttle is released, then you can relax and
leave the car in gear when stopped; your manual actions are redundant.
If it isn't wired properly, blame the installer, not the technology (and
change the wiring so it operates as intended ;^).
If you are using some other controller and are unsatisfied with its
safety features, blame its designers and either add additional safeties
outside of it, or replace it with a better designed controller. Again,
it is not the technology but the implementation that should be blamed.
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
--- In [EMAIL PROTECTED], "Michaela Merz" <[EMAIL PROTECTED]> wrote:
>
>
> Wouldn't it be possible to build a circuit that:
>
> Disables the contractor whenever the brake lights come on AND there is
> current (or voltage) on the motor? Wouldn't that clearly indicate the
> drivers desire to stop even though there seems to be power delivered
to
> the motor?
>
> Somebody able to draw up a quick circuit?
>
> Michaela
>
Excellent idea.....take the live from the brake light circuit and
connect to a relay coil, the other side fo the relay coil connect to
the lowside of your motor, the side being switched to ground.
The NC contacts of the relay are wired into the main contactor coil
circuit. If you hit the brakes and the motor is switched to ground the
relay energises and drops the main contactor.
An additional pair of relay contacts can latch the relay on to another
positive supply, so should you take your foot off the brake the main
contactor is still locked off, until the system power gets reset.
Well done , nice idea !
--- End Message ---
--- Begin Message ---
No! do NOT build this circuit, as you are interconnecting
pack voltage and 12V aux battery voltage, which is wired
to chassis ground. With this circuit, it would become
dangerous to touch your batteries or charge them through
most chargers, as they may connect the grid voltage to the
outside of the car.
You want strict separation between pack and 12V aux circuit,
except maybe in some well-defined cases with low voltage and
isolated chargers.
Be safe!
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 Chris
Sent: Thursday, January 04, 2007 3:20 PM
To: Michaela Merz
Subject: Re: Unsafe Controllers - Question ...
--- In [EMAIL PROTECTED], "Michaela Merz" <[EMAIL PROTECTED]> wrote:
>
>
> Wouldn't it be possible to build a circuit that:
>
> Disables the contractor whenever the brake lights come on AND there is
> current (or voltage) on the motor? Wouldn't that clearly indicate the
> drivers desire to stop even though there seems to be power delivered
to
> the motor?
>
> Somebody able to draw up a quick circuit?
>
> Michaela
>
Excellent idea.....take the live from the brake light circuit and
connect to a relay coil, the other side fo the relay coil connect to
the lowside of your motor, the side being switched to ground.
The NC contacts of the relay are wired into the main contactor coil
circuit. If you hit the brakes and the motor is switched to ground the
relay energises and drops the main contactor.
An additional pair of relay contacts can latch the relay on to another
positive supply, so should you take your foot off the brake the main
contactor is still locked off, until the system power gets reset.
Well done , nice idea !
--- End Message ---
--- Begin Message ---
The KillaCycle web site has been updated! Check out:
http://www.KillaCycle.com
After several years of my neglect, I persuaded Dave Stensland to
revamp the KillaCycle web site. He has done an outstanding job as you
can see. (Way cool graphics and layout, don't you agree?)
Dave made it easy for me to alter the content. With the nifty control
panel, I can drag and drop photos, edit captions, add, edit, and
delete text. It is just perfect to keep pace with the constant
evolution of the KillaCycle. These days, with the help of the
KillaCycle team, Steve Ciciora, Derek Barger, Scot Colburn, and our
driver, Scotty Pollacheck, the KillaCycle evolves at an amazing pace!
You all will be able to see that evolution as it occurs, now that
Dave has built the new KillaCycle web site.
Bill Dube'
--- End Message ---
--- Begin Message ---
Lee wrote:
>Bruce wrote:
>> And they also have 430mF - 125VAC Mallory caps for $6 each.
>> That's only $0.11 per Farad-Volt.
>> http://www.excesssolutions.com/cgi-bin/item/ES2353
>
>This is worthless for your application. It is a motor starting
>capacitor, ...
Not only worthless, but pay attention: some manufacturers
incorrectly label their products, in this case the 430MFD
stands for microFarad, not the milliFarad Bruce assumed
or the MegaFarad that the capital M suggests.
it should have been marked uF with a greek 'mu' character
to indicate micro. Some write it with a slash: /u
The capacitor in question can be seen in use here, with the
correct mentioning of microFarad value in the text:
www.arraysolutions.com/images/Replacement%20of%20capacitor%20with%20a%20moto
r%20start%20capacitor.pdf
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 Lee Hart
Sent: Thursday, January 04, 2007 12:12 PM
To: [email protected]
Subject: Re: Surplus Capacitors - Was: Joe Sixpack Geo: best
controller...
Bruce wrote:
> Both of those surplus places had interesting web sites.
For controller input filtering, don't buy based on microfarads; buy
based on ripple current and ESR rating. This will be harder, because
you'll have to do some research to find out each capacitor's ripple
current rating.
> 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
Probably less than 1 amp each.
> 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
This is probably a better part for the application.
> 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
These are worthless here; far too low a current and too high an ESR.
> 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
(I corrected the url). This is the most promising. The screw terminals
imply a high ripple current and low ESR rating.
>
> And they also have 430mF - 125VAC Mallory caps for $6 each.
> That's only $0.11 per Farad-Volt.
> http://www.excesssolutions.com/cgi-bin/item/ES2353
This is worthless for your application. It is a motor starting
capacitor, only used for a second or so at a time. It has a high ripple
current rating, but bad ESR and will have an extremely short life.
--
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 ---
Dependent on whether you use regen or not (most DC systems
do not) there will still be a current in the motor for a
while after shutting the controller off, as it has the
path through the 'fly-back' diode, so do not draw a
conclusion too fast or you may have nuisance trips when
going from full throttle (building up a nice motor current)
to throttle released and start braking.
A reed-relay is a good and rugged and isolated sensor for
large motor current, it may not work so well for lower
power vehicles, possibly need to add magnetics to pick up
enough field to close with current and open with no current,
this can make the circuit impractical and unreliable.
The other issue is that the reed relay can carry only a tiny
current to avoid its sensitive magnetic contacts to be
welded or influenced by the self-induced current. It is also
closed on motor current, so you probably need a relay to
break the contactor control when the brake switch closes
AND the reed relay is closed.
An alternative is to measure the current into the controller
(at the battery current shunt) which usually is a 50mV signal,
use an opamp to multiply it about 100 times and send this
into an opto-coupler (with series resistor) so there is an
isolated signal of "high current draw" from the batteries.
This, together with the brake switch signal can also be used
to decide to drop the contactor and it will not be affected
by regen, because then the current is reversed so the opamp
cannot drive the opto-coupler, if you use a type with only
one diode. (I do have a variant that has two anti-parallel
LEDs which will signal high current in both directions)
The solution to always drop the contactor on throttle release
is a lot simpler though....
NOTE that if you have other HV loads, you will need to use
two contactors - main one for the controller, releasing at
throttle high and an auxiliary one to close when you turn
the car on, powering things like DC/DC converter, heater
and other auxiliary loads. You may need pre-charge to both
DC/DC and controller, so you may need 3 contactors total,
although the pre-charge and auxiliary contactor can be
low-current versions, only the main contactor needs to
carry full battery current to the main controller if you
wire it directly between battery and controller (plus the
breaker, plus ON/OFF switch, plus fuse in the pack...)
Regards,
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 Roger Stockton
Sent: Thursday, January 04, 2007 2:18 PM
To: [email protected]
Subject: RE: Unsafe Controllers - Question ...
Michaela Merz wrote:
> Wouldn't it be possible to build a circuit that:
>
> Disables the contractor whenever the brake lights
> come on AND there is current (or voltage) on the
> motor? Wouldn't that clearly indicate the drivers
> desire to stop even though there seems to be power
> delivered to the motor?
>
> Somebody able to draw up a quick circuit?
Yep; this is almost exactly what John Wayland proposed a few years ago.
I think his scheme used the potbox microswitch to detect that the
throttle was released, and if motor current is present at this time, it
would drop out the contactor.
I would not rely on the brake lights being on, but would instead use a
switch actuated by the brake pedal and/or the throttle microswitch so
that the safety system will work even if the brake lights don't ;^>
There should be a circuit in the archives somewhere (though I've never
really been very successful searching them for anything ;^).
Cheers,
Roger.
--- End Message ---
