EV Digest 7057
Topics covered in this issue include:
1) Re: Series/Parallel switching (was Re: Karmann Ghia Design - System
voltage)
by "Joseph T. " <[EMAIL PROTECTED]>
2) Re: Bridgestone Ecopia EP-03 Tires- how about B381's ?
by "Phil Marino" <[EMAIL PROTECTED]>
3)
by "Roger Stockton" <[EMAIL PROTECTED]>
4) Re: Cheap Rev Limiter
by Bill Dennis <[EMAIL PROTECTED]>
5) RE: Battery second string range implications ?
by "Steve Hawkins" <[EMAIL PROTECTED]>
6) RE: Cheap Rev Limiter
by "Dale Ulan" <[EMAIL PROTECTED]>
7) RE: Capacitor recommendations, ripple current
by "Dale Ulan" <[EMAIL PROTECTED]>
8) E-Porsche 914
by "Mark Hanson" <[EMAIL PROTECTED]>
9) Looking for zilla speed sensor mount design/picutres for double shaft
ADC motor
by Paul Wallace <[EMAIL PROTECTED]>
10) Re: Looking for zilla speed sensor mount design/picutres for double shaft
ADC motor
by Mark Dutko <[EMAIL PROTECTED]>
11) Re: What is the typical amperage draw of the field for a sepex motor?
by "Zeke Yewdall" <[EMAIL PROTECTED]>
12) Re: What is the typical amperage draw of the field for a sepex motor?
by "Zeke Yewdall" <[EMAIL PROTECTED]>
13) Re: Series/Parallel switching (was Re: Karmann Ghia Design - System
voltage)
by Steven Ciciora <[EMAIL PROTECTED]>
14) Re: E-Porsche 914
by David Dymaxion <[EMAIL PROTECTED]>
15) Re: Capacitor recommendations, ripple current
by Dan Frederiksen <[EMAIL PROTECTED]>
16) RE: Karmann Ghia Design - System voltage
by "Peter VanDerWal" <[EMAIL PROTECTED]>
17) RE: E-Porsche 914
by "Roger Stockton" <[EMAIL PROTECTED]>
18) Re: E-Porsche 914
by Dave Cover <[EMAIL PROTECTED]>
19) Re: Sebring EV info needed and don't feed the troll
by Mike Chancey <[EMAIL PROTECTED]>
--- Begin Message ---
"You would be better off in series (where they are drawing more than
1,000 amps)."
As I understand, as you accelerate and reach higher and higher speeds,
more rpm is required and less torque is needed. The way to achieve
higher rpm with an electric motor is with more volts. Therefore,
you're better off with each motor getting less than 1,000 amps because
that way they are getting more voltage, and producing more rpm, and
therefore reaching higher speeds. Am I wrong?
On 7/24/07, Steven Ciciora <[EMAIL PROTECTED]> wrote:
One small detail that could be inserted after "...the
current will decrease as motor rpm continues to
increase." The zilla waits for the current to
decrease to half of the parallel current limit that is
programmed into the zilla. For example, when racing a
Z2K, it is likely that the current limit in parallel
mode is 2,000 amps. So the zilla waits until the
motors are only drawing 1,000 amps in series before
shifting. If the zilla shifted sooner than this, they
would be drawing more than 1,000 amps (each) in
series. Since the zilla 2K can only put out 2,000
motor amps total, each motor can only see 1,000 amps
each when in parallel mode. You would be better off in
series (where they are drawing more than 1,000 amps).
- Steven Ciciora
--- "Joseph T. " <[EMAIL PROTECTED]> wrote:
> Series/Parallel switching motors is great!
>
> Bill Dube gives an excellent explanation on his
> website:
>
> "The Zilla Controller has the ability to operate a
> series/parallel
> motor contactor automatically. The motors are
> initially configured in
> series. Thus, the full controller output current
> travels through both
> motors. This gives maximum starting torque. As the
> motors spin up, the
> voltage across each of them increases. When that
> voltage matches the
> battery voltage, the current will decrease as motor
> rpm continues to
> increase. The Zilla will then switch the motors into
> parallel
> connection. This will double to voltage available to
> each motor, but
> will divide the current. The motors can turn much
> faster, but with
> half the torque. It result is just like shifting a
> transmission from
> low to high."
>
>
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--- End Message ---
--- Begin Message ---
From: "Joseph T. " <[EMAIL PROTECTED]>
Reply-To: [email protected]
To: [email protected]
Subject: Re: Bridgestone Ecopia EP-03 Tires- how about B381's ?
Date: Tue, 24 Jul 2007 15:09:40 -0400
How beneficial is using a LRR tire? EV calculators shows about a 20%
improvement in range, but that sounds like a little too much. Does
using LRR tires signifigantly reduce vehicle performence?
As far as range increase, there isn't a single answer.
It would depend on:(among other things, I'm sure)
1 The reduction in rolling resistance ( how bad were the old tires, and how
good the new)
2. The aero drag of the vehicle ( the lower the aero drag, the more dramatic
the range improvement by using LRR tires)
3. The type of driving ( speed, hills, stop-and-go vs steady speed)
4. Vehicle weight.
For example, at low, steady speeds, on the flat, most of the energy required
to move a car is lost in the tires. For that case, reducing the tire
rolling resistance could have a huge effect.
Phil Marino
On 7/24/07, Ricky Suiter <[EMAIL PROTECTED]> wrote:
Phil, the B381 was going to be my next choice
actually, but I kind of got caught up in the thrill of
the hunt when I was first told the Ecopia wasn't
available I guess. I do not have a rolling resistance
coefficient, but we'll see how they do. In the picture
you can download off Bridgestone's site the sidewall
of the tire actually says "FOR ELECTRIC VEHICLE USE
ONLY" so I'm hoping this set has that.
Actually lack of data has more than anything made me
curious to try different tires. My GEM has Bridgestone
Potenza RE92 165/65R14's on it (Honda Insight tire),
my Saturn conversion has Goodyear Integrity
185/65R15's on it and now I'll be adding this. All are
LRR tires in some capacity, but I don't have any
numbers for either. A friend of mine has a set of
Michelin Proxima RR tires (the EV1 tire!) and ordered
some Dunlop SP20's for his other car so we're kind of
comparing also. I guess one of these days we need to
take one car on the same route with the different
tires on it and see which is the best.
Rick
> > From: "Phil Marino" <[EMAIL PROTECTED]>
> To: [email protected]
> Subject: RE: Bridgestone Ecopia EP-03 Tires- how
> about B381's ?
> Date: Tue, 24 Jul 2007 07:29:30 -0400
>
> Ricky
>
> Another LRR tire - Bridgestone B381 (it's the
> lowest RR tire listed in the
> Greenseal document, at 0.62) iis available in stock
> from TireRack.
>
> I bought four of the 185/65 - 14 's for my Echo, and
> they also have
> 185/70-14 ( close to the same overall diameter as
> 195-65-14) for $83 with a
> load rating of 1201 lbs at 44 psi max.
>
> If this has enough load rating for your application,
> it might also be a good
> choice.
>
> Do you know the rolling resistance coefficient for
> the EP-03's? I don't
> think I've seen them listed in any LRR chart.
>
> Phil
>
>
> >From: Ricky Suiter <[EMAIL PROTECTED]>
> >Reply-To: [email protected]
> >To: EV List <[email protected]>
> >Subject: Bridgestone Ecopia EP-03 Tires
> >Date: Mon, 23 Jul 2007 23:39:11 -0700 (PDT)
> >
> >Ok so hoping this might help someone out there
> looking
> >for a purpose built LRR tire. The Honda EV Plus
> used
> >this tire in a 195/65R14 size, they still list it
> on
> >Bridgestone's web site. Although they list oem
> >fittment as a Honda Civic EV.
> >
> >So I first called up my trusted local Discount Tire
> >store, they had nothing in the computer about them
> and
> >recommend the Insignia tire in that size. Of course
> I
> >decline because I want *this* tire. I call the
> local
> >Firestone corporate store, they have nothing as
> well.
> >Hmm, ok I print out the information sheet and take
> it
> >to that store. There is an article number 060-070,
> >they search it in their system and sure enough it
> >comes up, but shows no stock at any of the local
> >stores. They get on the phone and call the main
> >warehouse who searches the article number and it
> comes
> >up national back order with no ETA. Frustrated I
> shoot
> >and email to Bridgestone corporate to see if I can
> get
> >these tires or not.
> >
> >I know the Ecopia EP-02, which is a truck and SUV
> size
> >tire is available on tirerack.com and was used on
> the
> >RAV4 EV. I didn't know if I'd be able to get the
> >smaller size Ecopia EP-03. I emailed tirerack even
> and
> >they said they weren't available.
> >
> >Sure enough I get a prompt reply from Bridgestone
> >saying they are indeed available, but they will
> have
> >to be special ordered from Japan and it will be mid
> >September by the time they arrive. They actually
> had
> >to enter the tire in to their system so it would
> show
> >it could be ordered, they even called the store I
> went
> >to and gave them the procedure to order them.
> >
> >Back to the store, they ordered them! Price per
> tire
> >is about $100, which is a bit more than usual but
> the
> >things are coming 8000 miles (that's a guess) from
> >Japan. I get a call 2 days later, they found a set
> >hidden somewhere in California so now I'm supposed
> to
> >have them within a couple of days. So I'll know how
> >they do in a couple days or a couple weeks
> depending
> >on where they're coming from. The amazing part is
> when
> >I talked to the Bridgestone sales rep who got them
> in
> >the system for me I only said "Electric Vehicle,"
> he
> >actually threw the term "low rolling resistance"
> out
> >there in our conversation! I was so impressed.
> >
> >So what are they going on? I acquired a decent
> >condition running 2002 Ford Th!nk neighborhood with
> a
> >8 month old set of Deka batteries and the updated
> >DelatQ charger! It needs paint and a little other
> >reconditioning, but I'm planning on putting the
> >aftermarket motor in it, reprogramming and getting
> the
> >thing to keep up with regular traffic. By some mix
> up
> >I was issued a full registration with it, not a NEV
> >registration so I am feeling justified. The other
> >factor in this decision is the stock turf tires
> (which
> >don't roll all that well) are no longer made. Ford
> >still has them available, but they want $150 a
> copy!
> >So that made my decision easier because for a few
> more
> >bucks I could put really good looking wheels on it,
> >have a LRR tire and get a few more mph out of the
> >deal. I have experience putting LRR tires on GEM's
> and
> >they seem to have lost no range that way while
> gaining
> >more speed.
> >
> >So if anyone wants a tire made for an EV they are
> >available no matter what anyone tells you.
> >
> >Later,
> >Rick
> >92 Saturn SC conversion
> >AZ Alt Fuel Plates "ZEROGAS"
> >
____________________________________________________________________________________
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--- End Message ---
--- Begin Message ---
Roger Daisley wrote:
> Using a Warp motor and Curtis 1231C.
>
> Is there a "cheap & easy" way to install some kind of motor
> rev limiter, so that when someone else drives the vehicle
> they can't accidentally over speed the motor ... Or I miss
> a shift and punch the throttle? There is a good sized tail
> shaft on the motor where something could be attached.
I suppose it all depends what you consider cheap ;^>
If you want something safe for when someone other than yourself drives
the vehicle, then you need something that is going to be dependable and
doesn't rely on the driver responding to some alarm or idiot light, etc.
Assuming the Warp tailshaft is the same size as that of the ADC, then
the cleanest/simplest magnet arrangement to trigger a speed sensor is
the magnet collar sod by EV Parts:
<http://www.evparts.com/shopping/product_details.php?id=444&product_id=1
568>
They've got a matching sensor as well:
<http://www.evparts.com/shopping/product_details.php?id=444&product_id=1
565>
(I notice that both of these seem to be more expensive than I remember;
glad I bought my magnet collar before inflation caught up with us ;^)
Canadian Electric Vehicles sells and uses an ISSPRO 2-stage rev-limiter.
If I recall correctly, the first setpoint is used to short out (or short
a resistor across) the pot box while the second drops out the main
contactor or controller KSI, etc. The rev-limiter is included in their
conversion kits, and Randy must have a sensor and magnet arrangement to
go with it, so you might want to drop him a line (or phone him) to see
what a complete or partial setup would cost: <mailto:[EMAIL PROTECTED]>.
The ISSPRO is nice in that it has dry contact (relay) outputs.
I would guess that you are looking at about $300 to implement reliable
overspeed protection, which is still pretty cheap compared to the cost
of a motor.
If you are reasonably comfortable building circuits, you could build
your own version of the ISSPRO device based around an IC such as the
LM2917 to save some money. If you wanted a cheaper speed sensor
arrangement, you could probably come up with a scheme to drive the
vehicle's original distributor from the tail shaft and use the original
variable reluctance pickup to trigger the homebrew speed switch, or
perhaps an aftermarket tach that includes a rev-limiter function.
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
How about this one for really clunky and low tech:
Paint black and white stripes on your motor tail shaft and and point
an optical reader at it that pulses ones every stripe change.
Hook that to your current analog tachometer
On the back of the tachometer's needle, glue a strip of aluminum foil
Drill two small holes through the back of the tachometer, one near the
pivot point of the needle and one near the tip of the needle, at the RPM
where you the motor to cut off
Run a wire from 12V positive to a solenoid, then from the solenoid to
one of the holes
Run a wire from the other hole back to 12V negative
When the motor reaches that RPM, the aluminum on the back completes
the circuit and energizes the solenoid.
The solenoid pushes open a switch that cuts off power to the main
contactor(s)
Bill Dennis
Lee Hart wrote:
From: Roger Daisley
Is there a "cheap & easy" way to install some kind of motor rev
limiter, so that when someone else drives the vehicle they can't
accidentally over speed the motor?
1. Attach a coil spring to the tail shaft. Put a bolt and nut on the
free end. Mount a bell just the right distance away. When motor RPM
reaches your limit, the bolt's weight stretches the spring just
enough to hit the bell. RRRiiinnnggg!
2. Mount any small permanent magnet motor to the tailshaft. It will
generate a voltage proportional to RPM. Use this voltage to drive
meter to display RPM, or to pull in a relay whose contacts operate
a warning light or siren, or simply cut the throttle.
3. Get the curves for your motor. See what current it draws at the
desired RPM at your pack voltage. Tape a reed switch to a motor
wire, positioned so it opens when the current goes below this.
Get a high voltage DC relay that pulls in at about half of your
pack voltage (which you can adjust with a pot in series). Wire
them up to activate a light or buzzer or throttle cutoff when
the motor draws too little current at high voltage (an indication
of excessive RPM.
They ain't elegant, but they are cheap and easy. :-)
--
"Excellence does not require perfection." -- Henry James
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart-at-earthlink.net
--- End Message ---
--- Begin Message ---
Rod, re: placement of the second string ...
www.hawkins.info/RXT-B
pictures are way down on the bottom of the page ... just an idea ...
-----Original Message-----
From: Rod Hower [mailto:[EMAIL PROTECTED]
Sent: Monday, July 23, 2007 8:14 PM
To: [email protected]
Subject: Re: Battery second string range implications ?
Joseph,
Sorry my response was somewhat cryptic.
I worked on the Dodge TEVan while at GE from 1993-1996
and drove this vehicle for 2.5 years while there.
I developed the charging program for NiCd and NiFe
batteries and qualified most of the motor
controls/chargers before they shipped to Chrysler.
I also owned a TEVan that I bought from Mike Chancey
(the EValbum guy) and drove this for 2 years as a
primary vehicle. My response to the paralleling of
batteries was based on the already bloated weight of
the TEVan at 5,000lbs. Adding an additional 1600lbs
of batteries is more than this control and motor can
handle based on my engineering background with this
vehicle. We are talking about a Dodge Caravan that
would weigh 6600 lbs and I have no idea where that
many batteries would fit. It has 6 battery trays that
are suspended under the frame and take up most of the
area under the vehicle (the inside of the van looked
like a normal Caravan). I'm guessing a parallel pack
would take up all of the passenger and cargo space
INSIDE the van. If we replaced ALL of the batteries
with something like a LI-ION pack at half the weight
(so the van would now be 4300 lbs) you may have a
minivan with decent performance and 300+ mile range.
But doubling the existing NiCd pack is not practical.
Rod
--- "Joseph T. " <[EMAIL PROTECTED]> wrote:
> I don't think you provide enough info for someone to
> calculate something.
>
> But this is a method that (I think) works. Divide
> your range by each
> battery. Therefore each battery will provide x
> number of miles. So
> then you can conclude that if you add x number of
> batteries, the total
> increase of range will be whatever.
>
> I also know some sort of calculation that is a rule
> of thumb. I forgot
> it though. It's something about taking the battery
> weight and dividing
> it by something, and then multiplying it by the
> car's mpg. (I don't
> know if it refers to real life mpg, or the old mpg
> ratings from the
> EPA that hypermilers would dream of.)
>
> On 7/23/07, Rod Hower <[EMAIL PROTECTED]>
> wrote:
> > Steve,
> > You better get a bigger motor and control, because
> the
> > one that's in there won't last long with that much
> > weight. I drove my TEVan with 500lbs of play sand
> for
> > the horse-shoe pit along with a bunch of other
> items
> > for a total extra weight of 800lbs. It was
> dragging
> > with that much extra weight, especially on the
> hills.
> > The motor would also overheat on warm summer days
> for
> > trips over 5 miles.
> > Rod
> > --- Steve Hawkins <[EMAIL PROTECTED]> wrote:
> >
> > > Does anyone have a good handle on the
> implications
> > > of adding a second
> > > string?
> > >
> > > I have a 180v string that weighs 1650 lbs. The
> car
> > > has a total weight of
> > > 5000lbs and an 80 mile range. If I add second
> > > parallel string and increase
> > > the weight by 1650lbs, what additional range
> would I
> > > be expected to achieve?
> > >
> > > Mathematician's input welcomed.
> > >
> > > Thanks,
> > >
> > > Steve
> > >
> > >
> >
> >
>
>
--- End Message ---
--- Begin Message ---
"Relatively Cheap"... LM2917 or LM2907 IC, a few resistors and capacitors, a
speed sensor to pick up a notch or teeth on the motor shaft somewhere, and an
output to drive a small reed relay to interrupt the gas pedal signal? Check out
the data sheet for that part. National Semiconductor makes it. The speed sensor
is the most expensive part but you can get one at a car wrecking yard pretty
cheaply. Building it shouldn't be that hard, but if you find building
electronics hard, someone in your area might be able to help in exchange for
maybe a case or two... You can use the same signal to run your tachometer. If
you already have a tach pickup, then you only need to add the shutoff/limiter
circuit.
-Dale
--- End Message ---
--- Begin Message ---
When I do rebuilds on older Solectria BRLS controllers (I've done
a couple), I've found some signs of insufficient ESR rating. If the
wrap on the caps has shrunk, then they've overheated. If they
haven't blown apart, then it's likely ESR issues and not
overvoltage. Anyways, I target having a ripple current rating of
at least half of the motor controller's output. That's over double
the original capacitor's ratings. You can get around 3 to 5A
ripple current ratings in (relatively) cheap caps, around 2000uF.
I use maybe 15 or 20 of these caps in a 240A/160V BLDC controller
rebuild. The ripple current rating at high frequency may be
different than that of low frequency, too. I use the Panasonic
UQ series. I'd like more ripple current rating but I can't fit
any more into the box.
-Dale
--- End Message ---
--- Begin Message ---
Hi,
My electrolyte on my Saft STM5-180's spit out at end of charge and was
curious how to prevent it. The Saft manual says to water the batteries one
hour after charge which I'm doing. I water about 10 cycles or once a week.
I'm thnking it would be better to water right at the end of charge where the
level is the highest. I don't want to dilute my electrolyte or murder my
batteries. My final charge rate is 7.5amps at 1.73V per cell as
recommended.
My brakes leave something to be desired. I have standard disc brakes on a
1820 lb vehicle, 16ea 6V batteries at 800 lbs total. Start weight is 2000
lbs with welded frame replacement I did. The GVW rating is 1690 lbs and it
looks like from the evalbum like most of these conversions are heavier than
mine. I turned the discs which helped a bit but the emergency brake just
slows down the vehicle not stopping it in an emergency like I'm used to. I
heard that 74' VW emergency brakes were really just like parking brakes. I
adjusted the venting clearance to .008" as recommended but may replace the
discs if that might help. Are there grabbier pads? I've been through the
heavy duty JC Whitney crap and have never really mailed down the best
material so just have standard semi-metalic. My master cylinder is the 17mm
instead of 19mm since the 17mm is easier to press.
The sloppy shifting leaves something to be desired, it looks ok with the
plastic ball end replaced on the side-shifter tranny in the back but I think
it's just a function of the design, long shift linkeage. the firewall
bushing looks ok. Any aftermarket shifters? I've checked with autoatlanta
& Pelican parts & Brad Meyuer who was very helpful in with the restoration
since October.
The roof cross brace with 2 lateral bars helped imensly with the flexi-frame
even after all the MIG welding.
Have a renewable energy day.
Mark in Roanoke, VA
_________________________________________________________________
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place! http://maps.live.com/?wip=69&FORM=MGAC01
--- End Message ---
--- Begin Message ---
I've got a new zilla 1k ehv with the stock motor speed sensor. I need
to mount the speed sensor on an ADC 9" double shaft motor. I'm sure
that someone has already built a bracket to mount the stock sensor at
the free end of the tail shaft. If you have pictures and/or dwgs and
measurements of such a bracket, please drop me a line.
Paul Wallace
/91 Chevy S10 full of almost dead SAFT nicads
--- End Message ---
--- Begin Message ---
I am in the process of doing this and the sensor alignment is so
close I am considering a different sensor, one without the cup, has
anyone used another type for this application?
On Jul 24, 2007, at 2:08 PM, Paul Wallace wrote:
I've got a new zilla 1k ehv with the stock motor speed sensor. I
need to mount the speed sensor on an ADC 9" double shaft motor.
I'm sure that someone has already built a bracket to mount the
stock sensor at the free end of the tail shaft. If you have
pictures and/or dwgs and measurements of such a bracket, please
drop me a line.
Paul Wallace
/91 Chevy S10 full of almost dead SAFT nicads
--- End Message ---
--- Begin Message ---
It's got two separate terminals for the field. And, I measured the
resistance between them -- 6.8ohms. Which I guess would translate to
only 14 amps at rated voltage (96 volts)
The previous owner said he only used field control for it, in
conjunction with the clutch. It seems like it would actually be
pretty easy to do this -- use a low amperage PWM controller, with the
pot-box reverse connected to give less voltage as you pressed down on
the accelerator, in series with a 25ohm 100 watt resistor in order to
insure that the field always had at least 1/4th of armature voltage.
Since I might run a 120 or 144 volt pack, I could also put a series
resistor to keep the field from ever getting full pack voltage.
Though that would also limit the ability to operate at base RPM.
Wonder if there's a way to hook some switches to the transmission,
such that when you put in in gear, it energized the main contactor and
spun the motor up with full field and armature voltages (too bad this
truck doesn't have a neutral safety switch). The, as you pressed down
on the accelerator (and let the clutch out) the field voltage would
be reduced, and the motor RPM would increase. When driving, if the
motor was turning faster than 1000rpm*armature voltage/field voltage,
then you would get regen braking, and it was turning slowing that
that, you would draw current to accelerate.
Just sort of rambling and designing out loud at this point.... am I
completely off base here?
Z
--- End Message ---
--- Begin Message ---
Ooops. Fixed a rather critical typo --- series vs parallel...
On 7/24/07, Zeke Yewdall <[EMAIL PROTECTED]> wrote:
It's got two separate terminals for the field. And, I measured the
resistance between them -- 6.8ohms. Which I guess would translate to
only 14 amps at rated voltage (96 volts)
The previous owner said he only used field control for it, in
conjunction with the clutch. It seems like it would actually be
pretty easy to do this -- use a low amperage PWM controller, with the
pot-box reverse connected to give less voltage as you pressed down on
the accelerator, in parallel with a 25ohm 100 watt resistor in order to
insure that the field always had at least 1/4th of armature voltage.
Since I might run a 120 or 144 volt pack, I could also put a series
resistor to keep the field from ever getting full pack voltage.
Though that would also limit the ability to operate at base RPM.
Wonder if there's a way to hook some switches to the transmission,
such that when you put in in gear, it energized the main contactor and
spun the motor up with full field and armature voltages (too bad this
truck doesn't have a neutral safety switch). The, as you pressed down
on the accelerator (and let the clutch out) the field voltage would
be reduced, and the motor RPM would increase. When driving, if the
motor was turning faster than 1000rpm*armature voltage/field voltage,
then you would get regen braking, and it was turning slowing that
that, you would draw current to accelerate.
Just sort of rambling and designing out loud at this point.... am I
completely off base here?
Z
--- End Message ---
--- Begin Message ---
I know I don't explain this very well, 'cause I've
confused many a person... so, note that my previous
example was why the zilla doesn't shift before the
series current drops to the the value of half the
current limit in parallel mode. If the zilla shifted
sooner, then in parallel mode, the motor current would
be _limited_ to 2000 amps total, or 1,000 amps per
motor, by the zilla's 2,000 amp overall limit. The
way the zilla limits motor current is by reducing the
motor voltage. Under these conditions, in series
mode, the zilla doesn't have to limit current, so it
doesn't have to back off on voltage. Under these
conditions, the motors see more voltage and more
current in seriese mode than in parallel mode.
Did that help clear up anything, or just confuse
things more?
Steven Ciciora
--- "Joseph T. " <[EMAIL PROTECTED]> wrote:
> "You would be better off in series (where they are
> drawing more than
> 1,000 amps)."
>
> As I understand, as you accelerate and reach higher
> and higher speeds,
> more rpm is required and less torque is needed. The
> way to achieve
> higher rpm with an electric motor is with more
> volts. Therefore,
> you're better off with each motor getting less than
> 1,000 amps because
> that way they are getting more voltage, and
> producing more rpm, and
> therefore reaching higher speeds. Am I wrong?
>
> On 7/24/07, Steven Ciciora
> <[EMAIL PROTECTED]> wrote:
> > One small detail that could be inserted after
> "...the
> > current will decrease as motor rpm continues to
> > increase." The zilla waits for the current to
> > decrease to half of the parallel current limit
> that is
> > programmed into the zilla. For example, when
> racing a
> > Z2K, it is likely that the current limit in
> parallel
> > mode is 2,000 amps. So the zilla waits until the
> > motors are only drawing 1,000 amps in series
> before
> > shifting. If the zilla shifted sooner than this,
> they
> > would be drawing more than 1,000 amps (each) in
> > series. Since the zilla 2K can only put out 2,000
> > motor amps total, each motor can only see 1,000
> amps
> > each when in parallel mode. You would be better
> off in
> > series (where they are drawing more than 1,000
> amps).
> >
> > - Steven Ciciora
> >
> > --- "Joseph T. " <[EMAIL PROTECTED]> wrote:
> >
> > > Series/Parallel switching motors is great!
> > >
> > > Bill Dube gives an excellent explanation on his
> > > website:
> > >
> > > "The Zilla Controller has the ability to operate
> a
> > > series/parallel
> > > motor contactor automatically. The motors are
> > > initially configured in
> > > series. Thus, the full controller output current
> > > travels through both
> > > motors. This gives maximum starting torque. As
> the
> > > motors spin up, the
> > > voltage across each of them increases. When that
> > > voltage matches the
> > > battery voltage, the current will decrease as
> motor
> > > rpm continues to
> > > increase. The Zilla will then switch the motors
> into
> > > parallel
> > > connection. This will double to voltage
> available to
> > > each motor, but
> > > will divide the current. The motors can turn
> much
> > > faster, but with
> > > half the torque. It result is just like shifting
> a
> > > transmission from
> > > low to high."
> > >
> > >
> >
> >
> >
> >
> >
>
____________________________________________________________________________________
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> >
>
>
____________________________________________________________________________________
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--- End Message ---
--- Begin Message ---
Heavy duty does not equal fast stopping. Go to a Porsche racing board and see
what they use. On my gas car I was amazed what switching pads did. Before I
could push the brake as hard as I could, no skid and no antilock action
(although these pads did last forever). I put in some Hawk brake pads, and now
I can easily engage the antilock brakes and even got some brief wheel lock at
my last autocross, with alot less pedal effort.
----- Original Message ----
From: Mark Hanson <[EMAIL PROTECTED]>
To: [email protected]
Sent: Tuesday, July 24, 2007 2:08:20 PM
Subject: E-Porsche 914
... My brakes leave something to be desired. I have standard disc brakes on a
1820 lb vehicle, 16ea 6V batteries at 800 lbs total. Start weight is 2000 lbs
with welded frame replacement I did. The GVW rating is 1690 lbs and it looks
like from the evalbum like most of these conversions are heavier than mine. I
turned the discs which helped a bit but the emergency brake just slows down the
vehicle not stopping it in an emergency like I'm used to. Iheard that 74' VW
emergency brakes were really just like parking brakes. I adjusted the venting
clearance to .008" as recommended but may replace the discs if that might help.
Are there grabbier pads? I've been through the heavy duty JC Whitney crap and
have never really mailed down the best material so just have standard
semi-metalic. My master cylinder is the 17mm instead of 19mm since the 17mm is
easier to press. ...
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--- End Message ---
--- Begin Message ---
thank you Lee. that was the conclusion I was reaching too. even the much
revered zilla2k with 1400 battery amps and only 26? caps must be well
under sufficient too.
In doing some leg work on this issue (which us trolls all do) I came
across a guy who had it on good authority that you can even get away
with using no caps on the battery side. He has had talks with an
engineer of a battery diesel eletric train in which they skipped the
caps entirely. He even claimed that batteries are not harmed by it and
that lead acid even benefitted from the shocks. not sure about that
though but I might investigate it. if actually viable that would be an
interesting simplification of the controller making it almost
ridiculously simple. right up my alley.
btw by 'good ones' I meant some with unusually high ripple current.
without doing an exhaustive search (digikey doesn't allow search by
ripple current) I found that panasonic lyt caps had higher than typical
ratings. maybe the Oatster use those in the zillas. I can't tell from
the pictures. Curtis have used Nichicon caps.
you say caps made for switch mode, do you know of any specific model
that qualify?
Dan
Lee Hart wrote:
The capacitors are in parallel with the batteries. The ripple current divides
between them according to the ESR (equivalent series resistance) of each of
these two parallel paths. Since the ESR of each is highly variable, it is
difficult to predict exactly how the current is shared.
In the Curtis controllers, they depend on the batteries to carry most of the ripple current, and so
use only "enough" capacitors to keep the voltage spikes down to "manageable"
levels. Sometimes this works (when the use has high-capacity batteries, and short, low-resistance
cables). Other times, it doesn't work (with low-capacity high resistance batteies and long wimpy
cables).
Can anyone recommend good ones in the 400v range
"Good" is highly dependent on the circumstances. As a rule, you want capacitors
with a ripple current rating of at least 10% of your controller's DC current limit, or
they will fail from overheating.
You also need a low enough capacitor ESR to minimize the voltage spikes on your
transistors and diodes. Again, its a judgement call based on how bad your
batteries are, and how much safety margin you designed into your transistors
and diodes.
In general, you should be using electrolytics built for switchmode power
supplies. They will have a much lower ESR and much higher ripple currnet rating
than electrolytics built as 60 Hz filter capacitors.
--
"Excellence does not require perfection." -- Henry James
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart-at-earthlink.net
--- End Message ---
--- Begin Message ---
I don't think it will even be 500 lbs, even if you include fuel and oil.
My guess is somewhere around 350 lbs.
A complete Type 1 VW motor weighs about 250 lbs. The only other thing to
remove is the gas tank which weighs 20lbs? not counting fuel.
> The ICE components do not weigh much in any air cooled VW. You may get
> rid of 500lbs. The engine is so light 1 strong person could carry it if
> it weren't so awkwardly shaped.
> Good Luck with your project. I'm sure you'll love it!
>
>> Stephen Paschke
>> Senior Consultant
>> Keane, Inc.
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
> Behalf Of Deb Hollenback
> Sent: Monday, July 23, 2007 4:21 PM
> To: [email protected]
> Subject: Re: Karmann Ghia Design - System voltage
>
> Thanks Bruce for the valuable battery sizing and donor info!
>
> I neglected to include weight stats - a 70ish Ghia weighs close to 1900
> lbs curb weight. I do not have GVW - anyone else know? I'm guessing
> the ICE components removed will be around 600 lbs. The main occupants
> of the vehicle will be myself and my lab/boxer - combined weight of
> 200lbs. I would like to add a passenger along with said pup
> occasionally - with the pup on a flat bed I envision to go over the
> batteries that will reside in the back seat.
>
>
>
>
>
> ________________________________________________________________________
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> recipient, please contact the sender immediately by reply e-mail and
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--- End Message ---
--- Begin Message ---
Mark Hanson wrote:
> My brakes leave something to be desired. I have standard
> disc brakes on a 1820 lb vehicle
> My master cylinder is the 17mm instead of 19mm since the
> 17mm is easier to press.
>From the archives, back in '98 Al Godfrey posted this about his 914:
>Having just done a brake upgrade by increasing the front
>pad area by 35 %, (swapping the Porsche calipers for BMW 320i
>units), and installing a higher displacement master-cylinder from a 911,
>I have much greater braking capacity on the front and now feel
>the urge to increase the rear braking proportionately.
I will note that when I drove Al's 914, the first time I hit the brakes, I
found the brake pedal travel unusually long and softer than I was
expecting/used to. I'm not sure of the diameter of the 911 master cylinder,
but would expect it to be a smaller bore based on the pedal feel (I can't
imagine the stock pedal travel being even greater!). My personal preference
would be for a large master cylinder bore and firmer, shorter travel pedal, but
that needn't affect the braking force.
Paul Compton responded:
> First you have to find out if you need any increace in rear
> brake bias. An empty carpark and a couple of observers are
> all the equipment needed. The front brakes should lock 'just'
> before the rears.
> The stock Porsche proportioning valve should be given Carol
> Smith's 'floatation test'. Drop it into a bucket of water,
> if it floats keep it. The only valve I've heard any good
> about is the one supplied by Tilton, all the rest have too
> much hysteresis, and drag the brakes on release.
[...]
> The best thing to install if you're after ultimate braking
> performance is, as someone else has suggested, a balance
> bar. Traditional Porsche designs have a strange effect on me,
> half the time I'll be thinking 'I like that, that's
> elegant' and the rest of the time I'll be thinking 'What was
> he on when he designed that!'. The pedal assembly and
> master cylinder installation in the 914 is one of the latter.
> Only Porsche could have chosen that awkward and vunerable
> to damage a position. On more than one 914 I've seen the
> cyclinder mounting is bent where the cyclinder had taken a
> blow over a speed hump or kerb. I'm not sure if there's room
> for a twin cylinder setup, but if there is I suggest you
> make your own. I can obtain a balance bar assembly (with a
> tube to weld to your brake pedal) for 35 pounds, cylinders
> run at about 25 pounds each (exchange rate $1.68 to the pound).
> The company I deal with will trade mail order.
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
--- Mark Hanson <[EMAIL PROTECTED]> wrote:
>
> My brakes leave something to be desired. I have standard disc brakes on a
> 1820 lb vehicle, 16ea 6V batteries at 800 lbs total. Start weight is 2000
> lbs with welded frame replacement I did. The GVW rating is 1690 lbs and it
> looks like from the evalbum like most of these conversions are heavier than
> mine. I turned the discs which helped a bit but the emergency brake just
> slows down the vehicle not stopping it in an emergency like I'm used to.
Mark
I've had good luck buying Porsche parts from the following two sellers.
www.paragon-products.com
www.pelicanparts.com
You should be able to get most everything you need to upgrade your brakes
through them. Don't
forget eBay, you can finad a lot there too. I've heard of the VW brake upgrade
but have no
experience with doing that.
And don't forget www.RennList.com for info and advice. There are a lot of
people who've already
gone through this and you can learn from them. Go through the forums and ask
questions if you
don't find your answer.
With my car (944) I turned the rotors, rebuilt the calipers, upgraded the pads,
replaced the brake
fluid with higher temp fluid and installed stainless steel lines. The only
thing left is to make
sure I have enough vacuum. I would be careful with the different options for
venting and drilling
your rotors. You may not always get better results. Cool is good, but you need
enough material in
the rotor to handle the heat.
Good luck,
Dave Cover, electric 944 in CT
--- End Message ---
--- Begin Message ---
Jerry wrote:
Hi All,
I need a diagram of a Sebring-Citi-car,
especialy the reverse wring from a later Sebring EV I'm
working on. It's been modified with a Curtis controller and
presently using a battery tap for the 12vdc curcuits so much
work needs to be done.
Also I couldn't find the Citicar list. Anyone
can give me a hand would be greatly appreciated.
The C-Car list can be found at:
http://autos.groups.yahoo.com/group/C-Car
There are some diagrams in the files section.
The 12 Volt tap solution was the way the originally built
them. Later ones added an auxiliary battery and charger.
Thanks,
Mike Chancey
Owner/Moderator
C-Car Egroup
--- End Message ---
