EV Digest 5342
Topics covered in this issue include:
1) Re: [solectria_ev] A Force broken in San Francisco Back on the Road
by Danny Ames <[EMAIL PROTECTED]>
2) Re: Orbital or Optima? For my Jetta conversion
by Doug Weathers <[EMAIL PROTECTED]>
3) Re: Orb Carnage....
by Seppo <[EMAIL PROTECTED]>
4) Re: Crazy DC regen idea, thoughts, comments
by "Robert Chew" <[EMAIL PROTECTED]>
5) So good to be back!
by "Electric Man" <[EMAIL PROTECTED]>
6) Re: AC vs DC; Newbie Question
by "Michaela Merz" <[EMAIL PROTECTED]>
7) Re: [solectria_ev] A Force broken in San Francisco Back on the Road
by "Mike Phillips" <[EMAIL PROTECTED]>
8) AC lockup, was: Re: AC vs DC; Newbie Question
by Jeff Shanab <[EMAIL PROTECTED]>
9) Re: Prius plug in over in England
by "Mike Phillips" <[EMAIL PROTECTED]>
10) Orbital or Optima? For my Jetta conversion
by Jeff Shanab <[EMAIL PROTECTED]>
11) Re: Crazy DC regen idea
by Lee Hart <[EMAIL PROTECTED]>
12) the $5000 car - could use some expert help
by multi-Timm <[EMAIL PROTECTED]>
13) RE: Motor options
by "Peter VanDerWal" <[EMAIL PROTECTED]>
14) Re: Orbital or Optima? For my Jetta conversion
by Ralph Merwin <[EMAIL PROTECTED]>
15) Re: Porsche 911 Was: How many amps driving my EV?
by "Peter VanDerWal" <[EMAIL PROTECTED]>
16) Re: AC vs DC; Newbie Question
by Lee Hart <[EMAIL PROTECTED]>
17) DC Controller Reliability vs AC Systems
by John Wayland <[EMAIL PROTECTED]>
18) Re: AC lockup, was: Re: AC vs DC; Newbie Question
by John Wayland <[EMAIL PROTECTED]>
19) Re: AC vs DC; Newbie Question
by Lee Hart <[EMAIL PROTECTED]>
--- Begin Message ---
Will Beckett (becketts) wrote:
Good to hear. Any word about making improvements to the gearbox based on
what you found?
- Will
Not with out a lot of expensive machining and modifications to the motor
to install dual thrust bearings on each end of the motor.
But it was suggested we drill a small hole in the top of the
transmission and pump the oil to let it drop into the gears.
Danny...
--- End Message ---
--- Begin Message ---
On Apr 8, 2006, at 10:43 PM, Brad Baylor wrote:
And found a few posts up (by Doug Weathers), the 34DC36 appears to be
the same as the 34XCD, but without side terminals. Is that the only
difference? Due to the lower cost, I'm heavily leaning toward the
Orbitals. :)
There are a couple of other reasons to prefer the Orbitals to the
Optimas.
- built-in handles (very convenient)
- easy to mount (put two 8inch 5/16" bolts right through 'em into the
surface underneath)
- more amps, according to our racing listers
The 34DC has stud terminals on the top, handy for connecting your
regulators. Also, they're a pretty blue color :)
As far as other comparable brands, there's been some talk on the list
about the Deka Intimidator batteries. I don't know of anyone who's
gotten their hands on one, let alone tested one or used them in an EV.
Group 31 batteries could get you the same amount of lead with fewer
interconnects and regs. Sixteen of them should give you about the lead
poundage you want. Marko Mongillo's Fiamp uses Optima group 31s.
Beautiful car.
<http://www.austinev.org/evalbum/206.html>
Brad in Tampa
--
Doug Weathers
Bend, OR, USA
<http://learn-something.blogsite.org/>
--- End Message ---
--- Begin Message ---
What would happen if you simply connected a (very sturdy) diode in
parallel with each battery? If the battery cannot keep in pace with
the others and starts to go negative, the diode would start
conducting the load current past the battery when the battery voltage
is down to -0.7 V.
Seppo
Jeff Shanab kirjoitti 8.4.2006 kello 19.16:
I just had a strange idea/question. Could the concept of a bypass
regulator be used in another way
disclaimer, this would be a really good way to waste money.
Could a bypass be made that bypasses a battery when too much
current is
asked from it?
like you have one battery in the string that can't keep up under hard
accelerations so it is shorted in such a way not to short the batttery
itself, an anolog version would be a SPDT relay which would drop
out if
the voltage dropped below a threshold.
Your pack voltage would take a 12V hit but you keep going. Would this
get you down the dragstrip faster than having a low voltage sensor
pull
back the current on the controller?
Now in a system of 25 12 volt cells, this is probably not much use,
but
if I have 100 li-ion cells, or 1000s of D-cells this might become more
resonable.
could a bypass be made that lets the battery still contribute?
B1--200A---B2--100A----B3----200A---...
|_____100A__|
--- End Message ---
--- Begin Message ---
Hi All,
Correct me if am wrong. Would it be possible to PWM the current to the
motor armature via the motor controller to the A1 and A2 terminals of the
ADC 6.7 inch and then grab the regen power from the field windings. Would
that be in AC current from the field windings?
From the field windings rectify the AC to DC to feed the batteries. And have
some ultra caps to smooth out the voltage peaks.
Cheers
From: Neon John <[EMAIL PROTECTED]>
Reply-To: [email protected]
To: [email protected]
Subject: Re: Crazy DC regen idea, thoughts, comments
Date: Sun, 09 Apr 2006 00:30:49 -0400
On Sat, 8 Apr 2006 13:55:08 -0700, "Electric Man"
<[EMAIL PROTECTED]> wrote:
>What about adding an isolated winding to the field coils of small gauge
wire
>with many turns, and then controlling it with a low current controller.
You
>might also be able to use this extra coil for field weakening, in the
"right
>pedal" mode. (I'm no big motor expert, but I think the term in developing
a
>magnetic field is 'ampere turns'.) There may be enough space to do
this...
You're correct in thinking in terms of ampere-turns and yes, this
would work, probably better than any of the other ideas, if there is
enough room for the windings.
I'm doing something similar to my Citicar's motor, not for regen but
for reverse without a reversing contactor. When I flip the direction
to "reverse", a single pole contactor will short the series field so I
won't have to fight its field, bypassing the armature current around
the field, and a shunt field with the same number of ampere-turns will
be energized.
I had plenty of room in the field for the windings. Since this is
momentary duty, the wire can be much lighter than for a continuous
duty shunt field.
I've prepped the motor and since I don't currently have a garage to
work in, I'm now waiting for the monsoon to end so that I can install
the motor and the controls.
The field bypass contactor handles high current but low voltage and
the duty cycle is short so I'm using a diesel starter motor solenoid
contactor. About $30 from NAPA. It and the shunt relay will be
energized through a microswitch on the throttle so that neither will
be energized except when actually backing up.
The bypass contactor must be as close to the motor as possible and the
wiring must be as heavy as practical so that the bypass circuit will
have much less resistance than the series field. Otherwise shorting
the field doesn't have much meaning. I thought about a SPDT contactor
to completely cut the series field out but that would again require
that a set of very high current contacts be in the motor-controller
loop.
I decided to do this instead of replacing a defective reversing
contactor because I didn't want to fool with the contactor, I didn't
want to spend the money for a new one, I wanted to get all the
contacts out of the high current motor-controller loop and I didn't
like the maze of high current wires for the F/R contactor. Plus I
wanted to try out my idea :-)
For regen, one would want MORE ampere-turns than with the series field
so that at a given speed, more voltage would be generated than what it
took to achieve that speed. That would make the controls much
simpler. Pretty much, just a reverse-biased diode to conduct the
regen back to the battery, some sort of low current field control and
probably a series field bypass contactor. I'd bypass the series field
to make control easier.
John
---
John De Armond
See my website for my current email address
http://www.johngsbbq.com
Cleveland, Occupied TN
A foolish consistency is the hobgoblin of little minds.-Ralph Waldo Emerson
_________________________________________________________________
Test drive new cars from the comfort of your desk at carpoint.com.au
http://secure-au.imrworldwide.com/cgi-bin/a/ci_450304/et_2/cg_801459/pi_1004813/ai_833884
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--- Begin Message ---
Hmm .. I think we all agree that a blown DC controller can cause some
problems. What about doing something about it? Wouldn't it be possible to
have a secondary system monitoring motor voltage and shut the system down
if something seems to be wrong?
i.e. the system should kill main power if there is voltage suplied to the
motor and break lights are on. That should be easy to build. But it
requires human intervention (pressing the break pedal).
Wouldn't there be a way (for an electronic circuit) to know the difference
between a PCM signal and a constant DC on the motor? It could trigger the
mains before the driver knows that the controller went south.
I think there might be ways to detect this kind of dangerous conditions
and to prevent a 'runaway' car :)
Speaking of lock-ups: I had two, in ICE cars, both on German 'autobahns'
at high(er) speeds. Once the transmission 'exploded' locking the rear
wheels in the process (for about 3 seconds); the other time, with an Audi,
the motor seized and blocked my front wheels. That one was scary because
it was raining and the car was not controllable. The mechanic told me
later, that a break section within the transmission should have prevented
a lockup, but, well, it didn't.
Michaela
--- End Message ---
--- Begin Message ---
Nice Job!
Does this happen much to Force motors?
If the bearings in your motor were toasted, what about the input shaft
bearing to the transmission? It spins the same speed as the motor and
was designed for half the rpm that the electric motor was running at.
Mike
--- In [EMAIL PROTECTED], Danny Ames <[EMAIL PROTECTED]> wrote:
>
> Wanted to share my good news.
> Just completed the final repair work today and its working great.
> With all the rain storms here in soggy California and my limited time
> available to work on the car it has been a challenge.
> Fortunately I was able to get a new sensor and get the motor in and out
> ok between dry times.
> Motor bearings were replaced due to excessive axial play.
> The sensor board was also bad due to it getting banged.
> Runs like a top.
> Danny
>
> Danny Ames wrote:
>
> >After several months of carefree driving we have now been down for
> >several weeks.
> >I have bee reluctant to post my story and a bit depressed and
needed to
> >do some checking.
> >In my several calls to various people feel ready to run this by
those on
> >the list.
> >What happened is the car starting bucking on de-acceleration and got
> >progressively worse till finally it stopped moving in downtown rush
hour.
> >I examined the speed sensor disk and could see the lines scratched off
> >where the detector pair on the speed sensor is placed.
> >I re-inked the disk lines with a sharpie and tried to makes several
> >adjustments but could not get it going at all and had the car towed
home.
> >Jacked up the front end so the wheels could turn freely.
> >Completely backed off the sensor and the motor would turn smoothly and
> >slowly.
> >In testing I adjusted the sensor closer in small increments to the
disk
> >and then the motor started to respond in a very erratic and rough
> >stepping motions. The axial motion of the motor armature starting
> >jumping about at what appears to be .125 inch so the disk is
moving to
> >and fro in this sputtering effect to the sensor and is very choppy
> >The motor bearings seem noise free but the armatures axial movement
> >maybe to great and the trouble possibly.
> >When the motor is at rest the disk is about flush to the motor face.
> >I can see the motor mounts with 3 bolts, so does one remove these and
> >simply slide the motor out.
> >Also how does the motor shaft engage to the transmission?
> >Hopefully I am on the right track to fixing this.
> >Danny
> >
> >
> >
> >
> >
> >
> >
> >
> >Yahoo! Groups Links
> >
> >
> >
> >
> >
> >
> >
> >
> >
>
--- End Message ---
--- Begin Message ---
I guess it depends on weather you are already moving or sitting at a
stoplight when the failure occurs.
While I agree a full lock up at speed is very dangerous I still think AC
may offer some extened areas of protection.
I think the real point is that a shorted transistor in a h bridge
configuration can be detected in an AC controller and shut down the main
power, or just stop the very next commutation, in fractions of a
second. AND it would take more than 1 transitor to fail at the same time
to put dc on a winding! Since often times the bemf is measured in the
winding that is not curently energized, you have alot of oppurtunities
to check for a shorted transistor
60 miles per hour at 24" OD tire is 1 mile/1min * (1 rotation / 2*pi*1
ft * 5280ft / mile )rot/mile = 840 rpm
assuming 10:1 gear reduction is 8400 rpm and for a 8 pole 3 phase motor
that is 560 hz , over 1500 checks per revolution.
Someone should check the math but the point is it can stop in under 1
revolution. In a non-racing situation this might chirp the tires, but it
is proably to short to translate through the suspension and cause a
stability problem.
In a DC controller, you have to infer it off of the input and the
current usage. An you must pop the main contactor, commutation is out of
your control. BTW How much is stored in the onboard capacitors in a DC
controller(like a zilla 1k)? how long will they take to run down once
the main contactor is popped?
--- End Message ---
--- Begin Message ---
Great article. It repeats itself. Some Paragraphs also repeat themselves.
Mike
--- In [EMAIL PROTECTED], Rod Hower <[EMAIL PROTECTED]> wrote:
>
> Sorry if this is a repeat, but I found this comment
> interesting
> "We thought we could do a much better job than Toyota.
> Doubling the car's efficiency seemed achievable. I've
> worked in the automotive sector and in battery
> industry and there is a huge skills gap between the
> two. One does not realise what the other is doing.
> That's given us a huge opportunity."
>
> Amberjac Plug-In Prius: Hail the 130mpg car
> Clever new electrics and batteries have transformed a
> hybrid into an amazing car, says James Ruppert
> Published: 04 April 2006
>
> Poking fun at the Toyota Prius has been a popular
> pastime. Owners including Cameron Diaz and Leonardo
> DiCaprio were getting nowhere near the claimed fuel
> consumption, and, most amusingly, the CO2 emissions
> are not even low enough to qualify for Gordon Brown's
> latest zero rate car-tax band.
>
> So stop laughing and start gawping at the Plug-in
> Prius. Not that there is a huge amount to gawp at, as
> it looks just like the standard-issue hybrid.
>
> And it has the same Prius ingredients - an efficient
> petrol engine, automatic gearbox, electric motor and
> additional battery pack. However, this Prius returns
> in excess of 100mpg in petrol-powered mode.
>
> Simon Sheldon, managing director of Amberjac Projects
> of Grantham, Lincolnshire, which is behind the Plug-in
> Prius, points to a tray of batteries. "Those are the
> original nickel metal hydride batteries, which we have
> replaced with lithium iron phosphate."
>
> These have seven times the capacity of the originals
> and the cars in which they are fitted get 27 times the
> energy. Plus, they are safe: Sheldon stabs a battery
> cell right through with a screwdriver without causing
> a fire. Indeed, the cell still works.
>
> As well as clever batteries there is also a cleverer
> battery management system, which helps this modified
> Prius to travel 30 miles in electric mode (30 times
> higher than the standard car) and allows it to return
> up to 130mpg compared with 50mpg in petrol mode.
>
> "We thought we could do a much better job than Toyota.
> Doubling the car's efficiency seemed achievable. I've
> worked in the automotive sector and in battery
> industry and there is a huge skills gap between the
> two. One does not realise what the other is doing.
> That's given us a huge opportunity.
>
> "To get to this customer-ready stage has cost about
> £150,000," says Sheldon. That is the annual coffee
> bill for major manufacturer boffins.
>
> At the rear bumper of the Plug-in is a flap which
> covers a socket. Unlike a standard Prius, you boost
> the batteries overnight on cheap-rate electricity (it
> costs only 21.9p to fill up), and that is the key to
> its remarkable urban performance.
>
> Engage the gears and you are off at a whisper, powered
> by the electric motor. You can have climate control
> and soothing music without flattening the batteries.
> There is a pod in front of the driver that tells you
> what the situation is.
>
> "Our monitor shows the battery condition and the
> throttle position," says Sheldon.
>
> In addition, there is the Toyota's own colourful and
> mesmeric energy monitor, which tells you what the
> power units are doing. After a few minutes in a
> standard Prius, the engine cuts in to help the
> batteries, but the Plug-in just keeps on going, and
> will travel under pure battery power for 30 miles.
>
> "We have had a problem describing what this car is,"
> says Sheldon. "It isn't strictly a hybrid, or purely
> an electric. It is in between. We still have to warm
> up the engine, and for that we do need to burn some
> petrol so that the catalyser works efficiently."
>
> We accelerate to more than 31mph and the petrol engine
> kicks in. The display, which was showing 999mpg,
> tumbles down to 52.5mpg. But that figure does not last
> for long, even though we are now overtaking on a dual
> carriageway. At 60mph we are doing 100mpg.
>
> Sheldon points out that it is reading in US gallons so
> I have to add 20 per cent, meaning a remarkable
> 120mpg. And when you coast up to roundabouts, you are
> only on battery power.
>
> So why do standard Prius owners achieve such poor
> consumption figures? "Their driving style needs to
> change," says Sheldon. "You need to anticipate
> conditions - there is no point in accelerating hard
> halfway up a hill. Toyota claims 65mpg but we have
> found that under normal driving conditions it is more
> like 48mpg."
>
> Unofficially, Toyota has seen the Plug-in conversion
> and could not believe that someone had
> reverse-engineered its baby so successfully. It will
> catch up, but is years of corporate development
> behind.
>
> Amberjac can now turn its attention to the hybrid
> off-roader Lexus RX400h, which gets Sheldon very
> excited: "At just over 30mpg it doesn't make sense,
> but we can easily double that figure and I believe it
> will look much more attractive."
>
> He's right. We could glide through the streets without
> upsetting any of the anti-4x4 lobby or, indeed, any
> wildlife. As I ponder this, an irate goose ignores the
> car and mounts a prolonged attack on our photographer.
>
> The Plug-in Prius is what the car should have been
> anyway, but at a price. Turn up at Amberjac with your
> Prius, and for £7,700 plus VAT you will have one of
> the most environmentally friendly cars in the world.
>
> The hardware can all be removed and transferred to
> your next Prius. Amberjac is also introducing
> lower-powered battery packs for drivers who don't need
> the ability to go 30 miles without an engine, and
> these versions will cost several thousand pounds less.
>
> If you can't afford this, Sheldon is hoping that local
> authorities and government will back up their green
> posturing with orders. Currently, the C02 output is
> reckoned to be about 60kg/km. When this is officially
> confirmed, it will unusually qualify the Plug-in Prius
> for zero rate car tax. And later in the year, Amberjac
> will switch the fuel to bio-ethanol.
>
> The Plug-in is a deadly serious piece of kit, perfect
> for A-list celebrities keen to offset the CO2 of their
> Lear Jets.
>
> Poking fun at the Toyota Prius has been a popular
> pastime. Owners including Cameron Diaz and Leonardo
> DiCaprio were getting nowhere near the claimed fuel
> consumption, and, most amusingly, the CO2 emissions
> are not even low enough to qualify for Gordon Brown's
> latest zero rate car-tax band.
>
> So stop laughing and start gawping at the Plug-in
> Prius. Not that there is a huge amount to gawp at, as
> it looks just like the standard-issue hybrid.
>
> And it has the same Prius ingredients - an efficient
> petrol engine, automatic gearbox, electric motor and
> additional battery pack. However, this Prius returns
> in excess of 100mpg in petrol-powered mode.
>
> Simon Sheldon, managing director of Amberjac Projects
> of Grantham, Lincolnshire, which is behind the Plug-in
> Prius, points to a tray of batteries. "Those are the
> original nickel metal hydride batteries, which we have
> replaced with lithium iron phosphate."
>
> These have seven times the capacity of the originals
> and the cars in which they are fitted get 27 times the
> energy. Plus, they are safe: Sheldon stabs a battery
> cell right through with a screwdriver without causing
> a fire. Indeed, the cell still works.
>
> As well as clever batteries there is also a cleverer
> battery management system, which helps this modified
> Prius to travel 30 miles in electric mode (30 times
> higher than the standard car) and allows it to return
> up to 130mpg compared with 50mpg in petrol mode.
>
> "We thought we could do a much better job than Toyota.
> Doubling the car's efficiency seemed achievable. I've
> worked in the automotive sector and in battery
> industry and there is a huge skills gap between the
> two. One does not realise what the other is doing.
> That's given us a huge opportunity.
>
> "To get to this customer-ready stage has cost about
> £150,000," says Sheldon. That is the annual coffee
> bill for major manufacturer boffins.
>
> At the rear bumper of the Plug-in is a flap which
> covers a socket. Unlike a standard Prius, you boost
> the batteries overnight on cheap-rate electricity (it
> costs only 21.9p to fill up), and that is the key to
> its remarkable urban performance.
>
> Engage the gears and you are off at a whisper, powered
> by the electric motor. You can have climate control
> and soothing music without flattening the batteries.
> There is a pod in front of the driver that tells you
> what the situation is.
>
> "Our monitor shows the battery condition and the
> throttle position," says Sheldon.
>
> In addition, there is the Toyota's own colourful and
> mesmeric energy monitor, which tells you what the
> power units are doing. After a few minutes in a
> standard Prius, the engine cuts in to help the
> batteries, but the Plug-in just keeps on going, and
> will travel under pure battery power for 30 miles.
>
> "We have had a problem describing what this car is,"
> says Sheldon. "It isn't strictly a hybrid, or purely
> an electric. It is in between. We still have to warm
> up the engine, and for that we do need to burn some
> petrol so that the catalyser works efficiently."
>
> We accelerate to more than 31mph and the petrol engine
> kicks in. The display, which was showing 999mpg,
> tumbles down to 52.5mpg. But that figure does not last
> for long, even though we are now overtaking on a dual
> carriageway. At 60mph we are doing 100mpg.
>
> Sheldon points out that it is reading in US gallons so
> I have to add 20 per cent, meaning a remarkable
> 120mpg. And when you coast up to roundabouts, you are
> only on battery power.
>
> So why do standard Prius owners achieve such poor
> consumption figures? "Their driving style needs to
> change," says Sheldon. "You need to anticipate
> conditions - there is no point in accelerating hard
> halfway up a hill. Toyota claims 65mpg but we have
> found that under normal driving conditions it is more
> like 48mpg."
>
> Unofficially, Toyota has seen the Plug-in conversion
> and could not believe that someone had
> reverse-engineered its baby so successfully. It will
> catch up, but is years of corporate development
> behind.
>
> Amberjac can now turn its attention to the hybrid
> off-roader Lexus RX400h, which gets Sheldon very
> excited: "At just over 30mpg it doesn't make sense,
> but we can easily double that figure and I believe it
> will look much more attractive."
>
> He's right. We could glide through the streets without
> upsetting any of the anti-4x4 lobby or, indeed, any
> wildlife. As I ponder this, an irate goose ignores the
> car and mounts a prolonged attack on our photographer.
>
> The Plug-in Prius is what the car should have been
> anyway, but at a price. Turn up at Amberjac with your
> Prius, and for £7,700 plus VAT you will have one of
> the most environmentally friendly cars in the world.
>
> The hardware can all be removed and transferred to
> your next Prius. Amberjac is also introducing
> lower-powered battery packs for drivers who don't need
> the ability to go 30 miles without an engine, and
> these versions will cost several thousand pounds less.
>
> If you can't afford this, Sheldon is hoping that local
> authorities and government will back up their green
> posturing with orders. Currently, the C02 output is
> reckoned to be about 60kg/km. When this is officially
> confirmed, it will unusually qualify the Plug-in Prius
> for zero rate car tax. And later in the year, Amberjac
> will switch the fuel to bio-ethanol.
>
> The Plug-in is a deadly serious piece of kit, perfect
> for A-list celebrities keen to offset the CO2 of their
> Lear Jets.
>
--- End Message ---
--- Begin Message ---
I am living that conversion/commute right now. Same distance, but lots
of lights and higher average speeds
I am using 24 orbitals, a zilla 1kHV and a 9" motor, but my beast is
heavy before the conversion, a 300zx
I used the 34xcd, they were easy to get, but the side posts were a pain.
the 34DC36 would have been better as all posts are on top.
I use one for my aux as I killed one of the 34XCDs by something being
left on ion the car draining it to less than 1V (still trying to wash
the handprint off my forehead)
I didn't insulate my batteries, they are bolted to an angle iron rack.
This looks like it might be a problem, It is not so much the reduced
range that gets me it is that there is a 2 day delay when the
temperature changes before the battery changes and 13 are inside the
cabin and 12 are under the hood. The emeter gets confused and balancing
is thrown out of wack. (my regs aren't working optimally, the switch too
fast. I bought the charger really early and the regs really late and
just happened to get a combination that don't play well togather, I need
to get a board upgrade when I get some mula) Temperature has been
wildly changing and I fear that Fresnos 100+ temps this summer will ruin
them. I need to remount in boxes with insulation and fans.
I mounted my regs on the batteries. Under the hood , I toasted a couple
as water got on them. I wonder if grouping them close to the batteries
in a water proof box would be close enough and protect them if a battery
decided to vent or seep a tad.
Orbitals are larger but my decision to go with them was two fold.
Available as we have an Exide warehouse in fresno and the testing done
by the racers that indicated they had stronger interconnects.
--- End Message ---
--- Begin Message ---
Jim Husted wrote:
>> Also I don't think you could braze the bars together as they would all
>> short,
Doug Weathers wrote:
> That's the point - you want them all shorted together to form one
> continuous conductor. A slip ring.
Yes, but you don't have room for 3 of them.
>> besides the melt factor to the bake-a-lite the coms made out of.
> I thought bakelite was sturdier than that.
Jim's right; it would be damaged by brazing temperatures.
> Then just solder the wires all together, one to the next. Presto, a
> slip ring. No arcing - they'll all be at the same potential. This
> sounds very easy to me.
That just gives you one slip ring. You need three. Well, 2 would work
for a single-phase winding. But if you're going to all this trouble, you
migth as well use 3 to get the benefits of 3-phase.
>> I'd opt for a press on coller over the brazing if in fact that would
>> work 8^ ).
> It would work. If you can find a high-conductivity tube with the
> correct inside diameter, that would be great. It increases the
> diameter of the "comm", so it might not work out as well with stock
> brush assemblies.
The slip rings should have a pretty big cross section, both for strength
to withstand high rpm, and to carry significant current (you could
easily pull 100+ amps from them). It's likely to be pretty difficult to
find 1/4" thick tubing to cut them from.
So I think a more likely route is to make them from 1/4" thick sheet.
Drill a hole in the center to clear whatever will be used as in
insulator (a sleeve of bakelite tubing around the motor shaft, for
example). Trim the outside basically round, and turn it to the final
diameter after it is mounted on the motor shaft.
The slip ring and its brush will have all the same problems as a
commutator with respect to surface roughness and out-of-roundness
causing brush chatter, wear, and shortened life.
Probably use something like mica disks as insulators between the slip
rings. There will still be some arcing and high temperatures at the
brushes. Mica will withstand it; bakelite or fiberglass may not.
I'd guess that these insulating disks should be a bit larger in diameter
and/or thicker than the normal spacing between commutator bars, to
provide enough of a gap to withstand the voltage. Commutator bars only
have ~30v between them. These slip rings will have the full motor
voltage between them.
--
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
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--- Begin Message ---
We are well into the development of our $5000 kit car that pretty much anyone
can afford. It can be assembled as an EV or a hybrid, depending on whether the
owner prefers a generator or more batteries in it's place.
We're well covered on mechanical and design, but we do lack some EXPERIENCED
experts in electrical. Currently there are only one or two guys who are expert
and doing all the pulling in electrical, so the group could use an extra person
or two on the team. If anyone is interested, you are most welcome to join us.
Hope to see you there:
autos.groups.yahoo.com/group/SmallEfficientVehicles/members
Timm
http://autos.groups.yahoo.com/group/SmallEfficientVehicles/members
T!MM! §
http://www.nrdc.org/wildlife/marine/nlfa.asp
http://groups.yahoo.com/group/Inventors-World/
http://groups.yahoo.com/group/CADoutsourcing/
http://autos.groups.yahoo.com/group/SmallEfficientVehicles/
"We don't see things as they are, we see them as we are" (Anaïs Nin)
---------------------------------
Enrich your life at Yahoo! Canada Finance
--- End Message ---
--- Begin Message ---
> Peter wrote:
>> Cutting the RPM by 20% might cause a 100% increase in current draw,
>> at a given voltage.
>
> True, but this has nothing to do with the torque/RPM curve.
> It is a result of the "back-EMF" of the spinning motor,
Except that I was not describing 'cause' I was talking about 'effect'. An
effect that is easily viewed by looking at a series motor's torque chart.
--
If you send email to me, or the EVDL, that has > 4 lines of legalistic
junk at the end; then you are specifically authorizing me to do whatever I
wish with the message. By posting the message you agree that your long
legalistic signature is void.
--- End Message ---
--- Begin Message ---
Brad,
As a data point for your decision, my Geo Prizm has 26 Optima YTs
in 13 pairs (156v). I have a Zilla Z1k controller. The car weighs
3500 pounds with me in it. My commute to work is 17 miles each way,
consisting of about 6 miles on surface streets and 10 miles on the
freeway at speeds of 65-70mph. Each leg of the commute uses about
30-33 amp hours, and I figure this is about a 50% DOD for my pack.
I recharge at work, so the pack sees two 50% cycles every day.
Will you be able to recharge at work? If so, you would be using
about 25% of your pack each direction, which would help give you
a long pack life.
Ralph
Brad Baylor writes:
>
> 87 Jetta GL 5 speed. My daily commute is about 16 miles round trip,
> with a top speed around 60 MPH (for 1 mile), and average about 20 MPH
> (heavy traffic). Motor will probably be the ADC FB1-4001A. I figure I
> should have around 1000 to 1200 lbs of batteries to stay around 30 to
> 40% DOD for decent life. I need 0 to 50 MPH around 7 to 8 seconds due
> to some tricky merges (my current car is a '96 Passat with the VR6).
> So that rules out 18 Trojan T-105s (which would be awesomely cheap).
> Controller will be the Zilla Z1K-HV or Z1K-EHV with motor current
> limit at max (~900 A) and motor voltage limit at 170. From searching
> the posts here, 170 V seems to be about the recommended max to prevent
> arcing damage (right?). 170 V at 900 A should get me the acceleration
> I need (right?).
>
> I'm considering 25 to 29 of one of the following:
> Optima Yellow Top D750S 43 lbs ~$160
> Orbital Marine 34DC36 41 lbs ~$100
> Orbital Extreme Duty 34XCD 41 lbs ~$100
>
> The Optimas seem to be tricky to find locally, as I haven't found a
> distributor nearby yet.
> The Orbitals seem to be easier to find and much cheaper. What's the
> difference between the 34DC36 and 34XCD? They both claim deep cycle.
>
> I'll be using Rudman regs on each battery and I'm hoping to get 3
> years life (about 750 cycles)
>
> Any recommendations (other brands, etc.)?
>
> Brad in Tampa
>
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THanks, Stefan.
I'd meant to mention that CdA was a more important measurement, but I
couldn't find any good info on the frontal area of the vehicles in
question (and using posted hight & width is highly misleading)
I was kind of wondering about the Camry. I still think a Saab might make
a better candidate since it seems to me they have a better load handling
capacity than the Porsches, and close to the same CdA.
I wonder what the CdA would be for a Porsche 914? As I recall the Cd
wasn't all that great, but it seems to me that it has even less frontal
area than a 911.
>
> Indeed:
>
> http://www.mayfco.com/tbls.htm
>
> These charts indicate much lower Cd*ft2 numbers for the Porsche line,
> BTW. They use manufacturers frontal area specs. I think the width and
> height of curvy cars like this leads to gross overestimations of frontal
> area. AKA a circle has less area then a square...
>
> Porsche 911 6.27
> Porsche 944 6.96
> Toyota Camry 7.57
> Saab 900 7.10
>
> My personal favorites:
>
> 68 Toyota 2000GT 5.76
> 90 Nissan 240SX 5.88
>
>
> ~ Peanut Gallery ~
>
>
--
If you send email to me, or the EVDL, that has > 4 lines of legalistic
junk at the end; then you are specifically authorizing me to do whatever I
wish with the message. By posting the message you agree that your long
legalistic signature is void.
--- End Message ---
--- Begin Message ---
Bill Dube wrote:
>> In many of these situations, an AC motor with shorted windings would
>> not be dangerous, but a DC motor connected directly to the pack would
>> be likely fatal.
Neon John wrote:
> I'll take a stuck throttle ANY DAY UNDER ANY ROAD CONDITIONS over an
> instant lock-up such as a shorted AC controller phase would cause.
I'd say the details make all the difference.
If you are stopped, and the DC controller fails at full throttle, that
is very bad. An AC controller that fails in full braking mode is
harmless.
Conversely, driving at high speed on a slick road when the DC controller
fails fully on in a relatively low-powered EV might not even be
noticeable right away. An AC controller that falls in full braking mode
could cause an immedate accident.
The key point is that these failure modes CAN HAPPEN. The design of the
EV should be such that a) the failure is detected, and b) something gets
done to prevent it from creating a dangerous situation.
The cheaper DC controls take a rather simplistic approach. They might
include or recommend a fuse, on the assumption that it will be sized to
limit the worst-case motor current (and thus torque) to something the
vehicle's brakes can handle. Or, you might depend on having a clutch and
the driver's reflexes to disengage the motor quick enough.
On a higher-power DC motor control and/or one with no clutch, this won't
work. You can't get it out of gear, and you can't fight off the motor
with the brakes. So, higher-end controllers like the Zilla have
automatic systems to drop the contactors if a failure occurs. If you're
building your own EV, you should include some equivalent system; perhaps
a switch that senses when the accellerator pedal being released, and
drops the contactors if the motor current fails to drop.
Most AC controllers are expensive, high-end systems. The designers
already thought about failures, and provided some means to handle them;
fuses, circuit breakers, or contactors that will drop out to prevent
dangerous lock-the-motor situations.
Some might say that an induction motor won't really "lock" with DC in
its coils. True; it still has "slip", and so still rotates at 50-100
rpm. But if your motor was at 10,000 rpm and it suddenly tries to go to
100 rpm, that's effectively the same thing as a total lock-up!
Some will say, "Sure, if a transistor fails shorted, you will get a
momentary surge of very high current. But the transistor will then blow
open, eliminating the short." That's also true; it happens sometimes.
But you cannot DEPEND on a transistor to fail open. There is a
significant probability that they can fail with a dead short, so low in
resistance that no realistic amount of fault current will "clear" the
short.
But you *can* depend on a fuse or circuit breaker failing open. They are
specifically designed to guarantee they will fail open within their
rated limits.
--
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
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--- Begin Message ---
Hello to All,
Michaela Merz wrote:
Hmm .. I think we all agree that a blown DC controller can cause some
problems. What about doing something about it? ...a secondary system monitoring
motor voltage and shut the system down if something seems to be wrong?....a way
(for an electronic circuit) to know the difference
between a PCM signal and a constant DC on the motor? It could trigger the
mains before the driver knows that the controller went south....ways to detect
this kind of dangerous conditions and to prevent a 'runaway' car :)
It's already been done...it's called a Zilla with Hairball.
All Zillas are controlled by the Hairball interface. First and foremost,
Cafe Electric builds the most reliable DC power stage ever, period! His
power stages simply don't blow, that in itself is amazing, but when you
consider the very high up-to 2000 amp currents (even the 'small' one
kicks out 1000 amps!) and the industry leading up-to-348 volts and they
still don't blow, is incredible! Lesser controllers have a hard enough
time managing 500 amps and 156 volts :-) The Zilla controllers power the
worlds quickest electric drag cars, and don't blow even under these
extremes.
I've got credibility here and have 'been there, done that' in regards to
blowing things up. The 5300 lb. Red Beastie electric Toyota truck Dick
Finley and I put together was the ultimate test bed for seeing how
robust controllers were. With a 2500 lb. battery pack capable of running
the truck for hours on end at high average currents and at very high
currents during hill climbing events, it ate 6, count 'em, 6
controllers! Having been involved in too many conversions to list over
my 26 years of EVing, I've blown up more controllers than most, believe
me. I think my 'We blow things up, so you don't have to' mantra was part
of Otmar's inspiration to make his Zilla line of controllers bullet
proof (or would that be plasma proof?). The original Godzilla controller
used to set world records in White Zombie never failed, ever. It lived
through everything I threw at it, including the melt-down of the
armature in the 11 inch Kostov under full power. It's still in perfect
condition and awaits its new owner (I'll let him tell everyone when he's
ready).
In the very unlikely event of a Zilla power stage failure, the Hairball
instantly drops out the contactors, and in many circumstances, it will
sense a problem 'before' the power stage can blow and not allow any
contactors to pull in. Old fashioned Curtis controllers don't have this
feature, nor do many other old tech designs. I was at Oat's side when he
was first working on the Hairball interface, and even gave him my input
on his ideas for its features and multitude of protection
circuits...even threw some of my own ideas at him ;-) The prototype
interface was a mess of tangled wires strewn all over the place as he
was first conceiving the idea, looking very much like what the cat
coughs up...hence, Hairball.
DC controllers 'can' be every bit as safe and automatic in their control
systems as any AC system, the Hairball/Zilla combo is proof.
See Ya.....John Wayland
Zilla biased (for good reasons) and sponsored by Cafe Electric
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Hello to All,
James Massey wrote:
BTW has anyone got any evidence - any documentation or other record -
of an on-road AC drive EV locking up due to power stage failiure? I'd
be surprised if there are any. I know *in theory* it can happen - but
has it in practice?
It happened to the GM guys as they were developing the Impact (that
became the EV1). One version used twin AC motors and inverters. One
inverter failed (I think), locked up the motor, and the car went into a
wild spin as the driver filled his shorts! I was not there, so this is
something like third hand knowledge. I cannot 'for sure' say it was a
failed inverter, as it may have been the motor itself that had the
problem, but I do know the twin motor car had one motor lock up, and it
wasn't pretty.
See Ya....John Wayland
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Mike Phillips wrote:
> The biggest thing that bugs me about most DC systems is the huge
> amount of current the batteries have to supply just to leave a stop
> light.
You'll only have a huge battery current if you're drag racing. A normal
start does *not* draw high current, because the controller steps the
voltage down and the current *up*.
On a typical start, my EV will draw 25-50 battery amps initially, slowly
rising to 200-300 amps as the car speeds up. Motor amps will be
something like 150-250 amps initially, and stays there until the car
nears the final speed (the controller is basically in constant-current
mode). On a motor rated at 160 amps continuously, that's not hard on it
at all.
The situation with AC is identical. The battery current is low, and
motor current is high, because the inverter is stepping the voltage down
and current up.
> With most AC systems you need higher voltage to get the watts up,
> but the battery pull 500 amps max on the high powered systems I am
> familiar with. Many limit to 200 amps. That makes battery and
> interconnect choices easier.
Watts are watts. Size the wires, transistors, etc. for the power
involved, and the pack voltage has no effect.
> The only AC failure I've ever known was when the 12v accessory battery
> got hooked up backwards ;)
I have a couple dead AC controller, and have seen many more. There are
*lots* of other failure modes, believe me!
I think you see fewer "stuck" AC controllers because in general they are
better built than the DC controllers.
--
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 ---
