EV Digest 6052
Topics covered in this issue include:
1) Dimboy charger dangers
by Steve Condie <[EMAIL PROTECTED]>
2) another zilla, yet EV
by Cor van de Water <[EMAIL PROTECTED]>
3) Re:Playing with an EV-1 and/or GM... Any suggestions?
by Chip Gribben <[EMAIL PROTECTED]>
4) Re: EV controllers? Practical parameters
by "Dave Wilker" <[EMAIL PROTECTED]>
5) Re: Current multiplication, was: EV controllers? Practical parame
ters
by Cory Cross <[EMAIL PROTECTED]>
6) Re: NiMH number of cells don't matter for cycle-life
by Mike Phillips <[EMAIL PROTECTED]>
7) Re: EV controllers? the 4th option...
by "Rush" <[EMAIL PROTECTED]>
8) Re: After Market Electric power steering box
by Jeff Shanab <[EMAIL PROTECTED]>
9) Re: After Market Electric power steering box
by Jeff Shanab <[EMAIL PROTECTED]>
10) Re: EV controllers? the 4th option...
by "Lawrence Rhodes" <[EMAIL PROTECTED]>
11) Re: Reattaching Magnets on PM Motors
by "David Roden" <[EMAIL PROTECTED]>
12) Re: EV controllers? the 4th option...
by "David Roden" <[EMAIL PROTECTED]>
13) Who did kill the electric car?
by Christopher Zach <[EMAIL PROTECTED]>
14) RE: Current multiplication, was: EV controllers? Practical parame
ters
by Cor van de Water <[EMAIL PROTECTED]>
--- Begin Message ---
(Note: posting order inverted for clarity)
David Roden <[EMAIL PROTECTED]> wrote: On 21 Oct 2006 at 8:41, Steve Condie
wrote:
> dimboy charger ...
Initially cheap, yes; but you'll pay for it many times over in operating
costs, especially with VRR ("sealed") batteries. IMO, the truly frugal EV
builder invests in a high quality, microprocessor controlled smart charger
and/or BMS which will minimize his or her long term cost of ownership.
David Roden - Akron, Ohio, USA
>>>>>>>>>>>>>>
I wouldn't necessarily disagree with this, except I've read lots of horror
stories on this list from owners whose batteries have been damaged by "smart
chargers" which were either set wrong, miscalibrated, or just plain
malfunctioning. I think there's actually no substitute for simply paying
attention to your batteries. Read their voltage frequently; know the amps
you're putting into them, observe the current taper as they charge up. I've
come to be of the opinion that battery charging is 50% science, 50% art, and
50% magic. (You can do that with magic, you know.) Seeing the amp draw at
different charger settings starting with a pack at different voltages after
different trip lengths teaches you the personality of your pack. I know most
people aren't going to be very interested in this (is there anything geekier
than what I just wrote?) but I suspect it may be the route to a long and happy
relationship with your pack.
One saving grace about a dim boy charger with a pack in the mid-hundred volts
area is that the most you can charge at is about 7 to 8 amps without tripping
your circuit breaker, and by the time the pack has been brought up to the 14+
volt per battery level the current has usually tapered down to 2-3 amps at
most. This will charge a 100 amp hour AGM pack overnight, and even if you
forget to set your timer to drop the voltage to float level after the
appropriate time passes your batteries should be able to handle the low amps
being pushed through at the higher voltage bulk charge setting without much
damage. A lower voltage pack of 200+ amp hour floodies might be a different
matter. I suspect that some of the bad reputation bad boys have gotten in the
past may come from using them to charge floody packs of 120 volts or less.
There I can see how you could get in a lot of trouble pretty quickly.
There's really nothing better than getting the best equipment available -
Victor's AC systems, or a Zilla teamed with a pair of Husted-tweaked Warps;
pass the PFC charger, please. On the other hand, I understand that a hundred
grand will buy me a Tesla, which would probably be better than anything I can
build in my garage. So it's all a compromise. I'm certainly in great risk of
being wrong, but I think a well tended dim boy may not be a bad match for a 144
or 156 volt pack of 110 amp hour AGM's. Unfortunately, I took my UB's out of
my truck after only 600 miles so I could put them in the Tropica; it'll be a
year before I can post any significant data. As of now, 12 are between 13.12
and 13.15 volts a week after removal. The thirteenth (the "rogue") is at
13.05. But it doesn't look like I killed them with the dim boy in the first
six months and 600 miles, anyway.
---------------------------------
How low will we go? Check out Yahoo! Messengers low PC-to-Phone call rates.
--- End Message ---
--- Begin Message ---
e-Zilla RC car
http://www.hotbodiesonline.net/e_zilla.html
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 eFAX: +1-610-423-5743
Take your network further http://www.proxim.com
--- End Message ---
--- Begin Message ---
Arthur,
Get the EV1 going again. It's been done by Brigham Young University.
They race a Silver GM EV1 powered by ultra-capacitors. They have the
NEDRA record for their class. They came out to Maryland to the Power
of DC to race it back in 2005. It's an awesome car.
If you have the technology and know-how to build your own controller
just do that to get it going again. It would be nice to have another
one on the road again. These cars shouldn't be mothballed.
I'm actually speaking from experience in bringing EVs back from the
dead. Our EAA Chapter, EVA/DC, bought MITs Aztec Solar Race car for
$1.00 and we trailered it back to DC in pieces and spent 2 years
restoring it to running condition. It features a carbon fiber body
with gull-wing doors, Solectria drive train, solar panels and seats 2
people. It also features some used parts from my personal EV
including my K&W charger, Curtis pot box and an old Albright
contactor. Alot of us in the club either donated parts and/or put
time and money into the project to get it running again. We have it
registered with the State of Maryland and are working on getting the
solar array up and running again.
We've raced the car at the NEDRA Power of DC and we get invitations
to show it at various solar and environmental functions around DC.
It is alot of work but well worth it.
Chip Gribben
http://www.evadc.org
http://www.nedra.com
On Oct 21, 2006, at 11:23 PM, Electric Vehicle Discussion List wrote:
From: "Arthur W. Matteson" <[EMAIL PROTECTED]>
Date: October 21, 2006 6:42:24 PM EDT
To: [email protected]
Subject: Playing with an EV-1 and/or GM... Any suggestions?
I rarely start threads here, but there was no question about this one.
As I may have mentioned before, I'm involved with the Solar Car
Team at
Michigan State University (I'm the longest member). We've recently
learned that the race for 2007 may not happen because of a lack of
funding. Besides that, we've never had a car before and are
finding it
difficult to get motivation and knowledge to build one from scratch.
So, the new advisor and I had a talk about other options.
A couple of years ago, the professor who I now work for in graduate
school took his class to visit MSU's EV-1. I wasn't in the class
at the
time, but one of my friends who coincidentally got to test the car
(Delphi employee, now a Ph.D. in E.E.) called me and I tagged
along. Of
course, I brought my camera. Pictures can be seen here:
http://mywebpages.comcast.net/awmatt/msuev1.html
The advisor and I came up with a suggestion of adding solar panels
to it
and/or using it to experiment with. (GM of course wanted to design it
with a solar panel, but they found it would increase the cost too
much.)
I just think it would be fun to see it go, no matter what we did. It
would be better than what we have now, that's for sure. I see this
as a
huge opportunity that I don't want to pass up; how many of us would
even
get this chance?
So I wrote an E-mail to two people that are in charge of taking
care of
it, or giving access to it (I'm concealing their identities). Their
responses are shown below. We also have a hybrid car from a team that
existed a few years ago. Keep reading after this!
First message, from 'Shop-Supervisor':
You are welcome to visit/view the EV-1 at your convenience. You may
wish to let the folks at 'MSU-Building' (555-5555) know that you will
be coming by and arrange a time when they can let you into the
storage
area.
Please check with 'Assistant-Dean' about authorized uses for both the
hybrid and the EV-1.
My only thought is that there may be some space problems in the Solar
cage if you are planning to have one or more of the cars in your cage
at 'Solar-Car-Garage.'
Let me know if you have any questions.
Thanks,
'Shop-Supervisor'
Second message, from 'Assistant-Dean':
Please see the attached letter from GM. They had us and other schools
(Wisconsin got a red one) write a proposal to get an EV-1, and
then GM
got significant liability concerns. They put many restrictions on the
use, removed the batteries, and took other measures to essentially
make the car inoperable. So it has "zero" range. As we are paying for
storage with essentially no use, we have been considering
disposing of
both cars, but I haven't had the heart to junk a classic collector's
item.
As I read the attached letter, the vehicle could be cannibalized for
parts for another use, or use its components as visual aids in a
class. The third bullet would suggest we can't get it running "as an
EV-1".
The hybrid is ours to use as we wish.
Like 'Shop-Supervisor,' my primary concern is whether you have space
to bring this vehicle to 'Solar-Car-Garage.' I suggest you and your
team go out and take a further look, and have further conversations
with 'Shop-Supervisor' about your intent.
- 'Assistant-Dean'
Now I bet you all want to see the attached letter from GM. So I've
attached it here in HTML format. Just kidding!
I'll provide it in edited graphic and text format, but I'll need your
help to interpret it! (It was written long after MSU got the car,
since
I saw it in November 2003.)
http://www.egr.msu.edu/~mattes12/ev1.gif
'Advanced Technology Vehicles' Letterhead
November 7, 2005
Dear Dr. Professor:
We hope that you are enjoying the use of the GM EV1 for educational
purposes and that it is providing a good learning opportunity for
your
students in automotive technology.
We wanted to remind you that as part of the donation agreement that
the university signed, the school and its representatives agreed
that:
- It would not sell, give away, donate or in any way transfer
ownership of this vehicle or any parts or components therein.
- If you find you no longer can use the vehicle and/or its
components,
the school will scrap them in an appropriate and environmental
manner,
and/or contact GM for assistance in scrapping.
- The school will not attempt to get the vehicle running again as an
EV1.
- The school will not attempt to get EV1 parts for the vehicle from
GM, a Saturn retailer, or any other source.
We trust that you will continue to abide by this agreement. If you
have any questions, please contact me.
Thank you for your continued cooperation.
Sincerely,
'EV-Program-Manager' (hand-signed)
I like how she says to contact GM for assistance in scrapping. Yeah,
they're awfully good at that. I guess if you're going to scrap an
electric car, you might as well do it environmentally!
Questions for the EV-List:
- Any ideas of what to do with the EV-1, that would be legal?
- Should I try to get in contact 'EV-Program-Manager' at all?
- What should I tell the Solar Car Team advisor, the 'Shop-
Supervisor,'
and the 'Assistant-Dean'?
- The hybrid car MSU built from scratch (I think) can be seen at the
left of some of the EV-1 pictures. You might get a glimpse of its
name,
"Spartan Challenger." Should we do anything with it? I think the
EV-1
would be 100 times as fun.
- The team still wants to put effort into building a solar car, albeit
not much. How would I deal with having two projects? Any ideas on
how
to connect the two so the team doesn't think we're giving up on the
solar car?
- I could easily build a three-phase motor controller to at least get
the car going (be forewarned: I'm not ready to sell controllers yet).
We can supply our own batteries, since we still have some money left.
- Also...the Solar Car Team's never-used, two-year-old pack of (8)
Trojan SG-50s died. I charged them once in a while; they never worked
particularly well. Where did I go wrong? Can they be revived? They
act like a leaky 100uF capacitor with a 16V zener diode across it, and
make lots of bubbling noises. (On the contrary, my Renault's flooded
marine batteries from Sears are still fine after six years.)
- Should I provide a showing of WKTEC to the Solar Car Team and our
advisor (he's already "green")? I haven't seen it yet.
- Any other comments or suggestions?
- Arthur Matteson
Master's candidate, Elec. Eng., MSU
--- End Message ---
--- Begin Message ---
Oh, I see!
Does it use RCL circuits for voltage and current division?
David C. Wilker Jr.
USAF (RET)
----- Original Message -----
From: "Paul G." <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Saturday, October 21, 2006 3:55 PM
Subject: Re: EV controllers? Practical parameters
On Oct 21, 2006, at 12:25 PM, Dave Wilker wrote:
The only way I know of is a step-down transformer.. Is that what you
mean? Or do you mean torque multiplication?
That is standard DC motor controller behavior. The watts in equals the
watts out. Watts is volts times amps. So if you controller is taking
120 volts at 100 amps in but the motor voltage is only 40 volts at part
throttle then the motor is getting 300 amps.
The catch is that the Curtis controller only limit motor current. Since
motor voltage will never exceed battery voltage the battery current
cannot exceed the motor current limit. Because of the motor current
limit there is a narrower peak power with a Curtis controller (one rpm,
when the motor is taking full voltage at max current and before it revs
any higher because then it won't take as much current.)
Separate motor and battery current limits allow for extra starting
torque and an extended power band. Lets say the motor current is 800
amps but the battery current is 400 amps. In this case the motor can
get 800 amps up to 1/2 pack voltage (400 battery amps), then the amps
drop as the motor voltage rises until the motor is getting 400 amps at
full pack voltage. That range of rpms is all at peak power. Extra
starting torque and a wider power band thanx to a better controller.
HTH,
Paul
--- End Message ---
--- Begin Message ---
Hi Cor,
The first purpose of capacitors is to protect the switching
elements. In order to feed the motor they must be capable of around
250Arms (in your case), which I doubt, in addition to needing enough
capacitance inversely to PWM frequency and minimum duty cycle. Do you
have part numbers and/or specs on those capacitors?
None of the golf cart controllers have enough capacitance. Judging
by the size of the Zilla, it does not either. I bet the VFD capacitors
are for power faction correction.
Cory Cross
Cor van de Water wrote:
Hi Cory,
Good controllers have large capacitors at the battery input
for this very reason - to smooth out the short pulses into
a constant battery current with very small ripple.
It is indeed a measure of how good the controller is, with
most SCR controllers this smoothing is not present, so they
will peak the same batetry current as the motor sees, making
the Peukert effect take a larger toll, that is why Lee
suggested to add large capacitors at the input of an SCR
controller, to increase range by drawing a constant current
from the batteries instead of short high peaks.
So - it depends on the controller!
BTW, in my 700V 250A AC controller more than half the volume
of the controller is taken up by 8 huge capacitors.
I think they are switched as 2 series groups of 4 parallel
if they are using standard 400V electrolytes, but I have
not cut that deep into my controller yet.
I have a salvage VFD (Variable Frequency Drive) that is
specified for 600V 3 phase and it also has 2 banks of
capacitors switched in series to take the voltage.
Note that the higher the switching frequency, the smaller
the capacitors can be, as long as their internal resistance
is low enough to take the AC current of the charging and
in particular the discharging peaks.
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 eFAX: +1-610-423-5743
Take your network further http://www.proxim.com
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Cory Cross
Sent: Saturday, October 21, 2006 5:18 PM
To: [email protected]
Subject: Re: Current multiplication, was: EV controllers? Practical
parameters
Cor van de Water wrote:
The modern switching controllers allow the *motor* current
to me many times larger than the *battery* current, in
particular at low motor RPM.
Nitpick -- they allow AVERAGE battery current to be lower. I recently
requested information (on the evtech list) on any experiments to see if
the high-frequency, low-duty-cycle draws consume at a Peukert's rate of
the average or motor currents, but there don't appear to be any studies.
Cory Cross
How? Simple - by sending battery voltage (and current) to
the motor for a very short period of time, which increases
the motor current quickly due to the low motor voltage at
low RPMs.
Then the majority of the time the controller disconnects
the battery from the motor, but since the motor acts as
an inductor, the current keeps flowing for a while, slowly
ramping down. The current flows through special diodes in
the controller output, which prevent the output voltage
from going negative by the motor current pushing through.
In low RPM situations the batteries may supply current
only 20% of the time, while the motor current loops around
through the diodes for the other 80% of the time.
Say the motor current is 500 Amps average, then the average
battery current is 20% or 100 Amps.
When you think this is impossible because energy cannot be
multiplied, it must come from somewhere then please think
about it as a transformer: low current and high voltage go
in at one side, high current at low voltage come out.
The above example may have a 200V battery pack while the
average motor voltage is around 36V.
(Yes, there is some loss in the controller and you can see
that the current goes from 20% to 100% while the voltage
goes from 100% to almost 20% - without loss it should be 40V)
Indeed - current multiplication is only effective when RPMs
are low, but then is exactly when you need it!
The motor current continuing to loop around can be thought of
as a wind-up toy: you can give it a quick turn, after which
is will run for a while, slowly losing speed. If you give it
a quick turn from time to time, it will continue going, just
like the controller giving the motor short bursts of battery
voltage to kick up the motor current, in between it will slowly
decay but as long as the ripple is small you will have a smooth
running motor at a much higher torque than the battery current
would suggest, because most current just loops around in the
motor and controller output diodes.
Hope this clarifies,
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 eFAX: +1-610-423-5743
Take your network further http://www.proxim.com
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Dave Wilker
Sent: Saturday, October 21, 2006 12:26 PM
To: [email protected]
Subject: Re: EV controllers? Practical parameters
The only way I know of is a step-down transformer.. Is that what you mean?
Or do you mean torque multiplication?
David C.. Wilker Jr.
USAF (RET)
----- Original Message -----
From: "Ryan Stotts" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Saturday, October 21, 2006 11:44 AM
Subject: Re: EV controllers? Practical parameters
Steve Condie wrote:
current multiplication
Hows that work?
--- End Message ---
--- Begin Message ---
Maybe it's not the already great batterys. Maybe it's the BMS too.
So I'd restate the 1st conclusion to include that number of cell
failures is greatly reduced when a BMS is doing it's job, not with just
the batterys alone.
I saw a large pile of EV95 battery's with bad cells in them. So I know
failures happen. Don't forget that the EV95's went in the Ford Ranger
and a Chrysler vehicle too. I wonder what their failure reports are
like?
Mike
--- doug korthof <[EMAIL PROTECTED]> wrote:
> Hi,
> The most tested and the most successful of all EV batteries is the
> Toyota-Panasonic EV-95. The last ones were built in 2003, just after
> the successful lawsuit by Chevron-Cobasys-Ener-Ovonyx that extracted
> $30M from Toyota-Panasonic.
>
> These FIVE (5) year old batteries now have a record of up to 105,000
> miles of succesful, carefree operation (using the advanced Toyota
> thermal-feedback BMS) and show no signs yet of degradation. As one
> Toyota manager puts it, "...we just don't have any credible reports
> of battery failure, and only one arguable case of battery pack
> replacement..." in the 328 Toyota RAV4-EV sold in the short-lived
> sales program of Mar., 2002 to Nov., 2002 (although many of the
> orders were not filled until late in 2003).
>
> Oil-company and government regulators, Toyota execs and others try to
> hide the fact that these batteries work and are in continuous usage
> by rather unskilled drivers; almost none of those driving the RAV4-EV
> are real EV converter. In fact, LADWP transportation services has a
> reputation for being completely ignorant of maintenance for their
> (slightly different) 2001 fleet vehicles (68 now are left); I just
> heard one RAV4-EV expert scoff at their record of mis-use, but theirs
> are still running fine even though hardly used (several have only
> 6000 miles after 5 years of use -- an astonishing $5.00 per mile!).
>
> Toyota itself, in the person of such as Dave Hermance, states blandly
> that "...the batteries are not ready" for plug-in hybrids, as if the
> EV-95 battery did not even exist!
>
> Yet put a small engine-generator on a Toyota RAV4-EV (one driver has
> done this) and you have, presto chango, a SUCCESSFUL PLUG-IN HYBRID.
>
> These batteries have statistics associated with them; over the 5
> years during which they were mass-produced (starting in Jan., 1997,
> when EV-95 went into production), failure rates were documented to be
> in the low single-digits per millons cells.
>
> The 24 battery modules in each Toyota RAV4-EV have 10 cells each
> (288v total, 14.5v max per module, 13.2v more reasonable operating
> level of "full"). These 240 cells balance, not just on MY RAV4-EV
> cars but on ALL REPORTING RAV4-EV down to .1v. Reading the OBD
> (using Hanssen and Shwabe's palm pilot display) shows that only at
> extremely LOW voltages (9.5v or less) does the difference in cells
> become more than .1v.
>
> This is TRUE whether the RAV4-EV battery pack is REGULARLY LEVELED,
> using the SPI magnecharger, or whether it it only occasionally
> leveled. In my case, I hardly ever level, usually filling to 80% or
> 90%; occasionally, I fast-charge using the 10 kW or 12 kW Manzanita
> (Rich Rudman) charger (hooks right into the regenerative brake
> shunt). In NO case is the battery pack, the cell integrity, or the
> performance impaired.
>
> My RAV4-EV has only 66,000 miles (since 2003), but others have more,
> and some have less.
>
> CONCLUSION: With Toyota-Panasonic NiMH EV-95 batteries, the number of
> cells is entirely IRRELEVANT to battery performance.
>
> SECOND CONCLUSION: Toyota could solve the "no battery" problem just
> by going into production with the known, reproduceable EV-95 battery,
> but won't, perhaps because of pressure from GM or perhaps because
> Chevron-cobasis-ener-ovonyx owns the patent rights, and won't let
> them.
>
> The batteries are here, and work; it's only the Western States
> Petroleum, and Dave Hermance, who pretend that they don't exist.
> Amazing, hundreds of working battery-powered cars, and no one can see
> them!
>
> /Doug
>
>
>
> >option. I would not want to have a 500 cell lead acid pack or a
> 800 pack of
> >NiCads if I had a choice.
>
>
--- End Message ---
--- Begin Message ---
James wrote -
> For someone like Rich to take on a project like this, I feel that it would
> take something like a subscription project. Everyone who thinks they will
> want one (or more) puts up (for example) $250 to Rich. They get the value
> of what they put up as a discount on their kit once they are ready and Rich
> gets the cash to do the project.
>
> What do people (and especially Rich, or anyone else who may be in a
> position to design such a system) think?
>
Well, Jerry Dycus has already done something like this and a lot of us
supported him. His 3 wheeler is coming along nicely. I think it is important to
support efforts that will benefit all of us. I would have no trouble at all
contributing an amount for development and then getting a discount when
'production' happens.
Developing something of this nature takes time, effort and materials. Making
sure that Rich has a bank account to draw on for development makes sense.
How many people are there on the list? 300 or so? If everybody gave $25 that
would be $7500... Think of it as membership or fees for all the good advice and
having our questions being answered by some pretty knowledgeable people.
Rush
Tucson AZ
www.ironandwood.org
--- End Message ---
--- Begin Message ---
Both the honda and delphi units work without the main computer. At least
they did when I researched them a few years back. They are both sold to
the car manufactures who are actually better at buying parts and
assembling them than people know.
The main difference is the delphi units used on the saturn vue (for
example) are column mounted between a regular box or rack and the
steering wheel. The honda units(bosch??) are assisted racks so are a lot
less useful for us converters.
--- End Message ---
--- Begin Message ---
Maybe it is time for the "open source" automotive computer.
When the proprietary wizards at GM,Ford,etc push it to far they will
be opensourced. Kinda the way the computer industry is evolving now,
with open source gaining momentum and propritary providers haveing to
actually provide value if they want to keep in the game.
The Zilla already has a lot of Car computer features. Mostly for
safety.
Perhaps the next step is for someone to design an EV ECM. It can drive
thru CAN whatever modules you buy, Charger,ACcontroller,DC
controller,Sepex controller, BMS, digital dash, etc. Software modules
can then be loaded for which ABS system you need to talk to or Body
Computers, Etcetera.
Humm, This is sounding good
--- End Message ---
--- Begin Message ---
http://www.logisystemscontrollers.com/ You might try these guys. Lawrence
Rhodes...
----- Original Message -----
From: "Joseph H. Strubhar" <[EMAIL PROTECTED]>
I can't wait 6
> months on a Z1K. Anyone out there have a new Raptor that you would sell to
> upgrade to a Zilla, and you can wait that long?
>
> I may have to go with a Cursit, but I'd prefer not to; If I do, can
someone
> help me with a precharge circuit? I can build it, but not design it.
--- End Message ---
--- Begin Message ---
Never tried it, but I've heard of success with JB Weld. It can even hold
broken magnets together. Clean case and magnet thoroughly with solvent
before applying the stuff.
David Roden - Akron, Ohio, USA
EV List Assistant Administrator
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--- Begin Message ---
John W. is passionate about this subject, that's for sure, but I have to say
that not everyone will react as strongly (and negatively) to Curtis
controllers as he does.
Really, how often do Curtis controllers fail full on when powered up without
a precharge? I don't recommend omitting the precharge, but I ran one that
way for years with no ill effects (I didn't know any better ;-).
I also disagree with John's recommendation to use a 1221B - unless the motor
is an 8" ADC or a Prestolite. From all the reports I've seen, the 1221B is
a buckin' bronco with a 9" ADC.
Now, about that "irritating non-varying squeal." We've been round and round
on this before but I'll post it again for the newbies.
It may be that John's ears are especially sensitive to this frequency. I
suspect he also is bothered by that EVs that aren't totally silent (although
squealing tires don't seem to bother him ;-). There is something to this.
However, for most people the "Curtis squeal" is hardly bothersome. It lasts
for a second or so when you accelerate. You may hear it when you're
creeping into a parking space. You'll seldom hear it otherwise.
It is NOT loud, certaintly not as loud as an ICE's engine. People will NOT
laugh and point at your car. Dogs will NOT run howling from the vicinity.
Indeed, most people (or dogs;-), inside the car or out, won't notice it at
all.
The brief bit of whine when accelerating is NOT a big deal, and it provides
significant benefits. Having that short period of low frequency chopping
allows the controller to have a smooth takeoff with the commonly used 9" ADC
series motor. It will provide good current limiting at low power while
still having a relatively simple, low cost circuit.
I used a Curtis PMC-25 controller for years. It chopped at 2 kHz all the
time (I think it used bipolar transistors). I never found the slight whine
it produced (with a Prestolite motor) at all obtrusive. Most of the time
the noise was drowned out by the tire noise on the road. When I could hear
it, I appreciated knowing that the drive was still in current limit so I
could pick the right gear and open up for highest possible efficiency.
I also used an ancient PMC DCC-96 in my Comuta-Car, and it chopped at 4 kHz.
I hardly ever heard it over the rattling, creaking body and whining axle
gears. But that may be a special case. ;-)
Thanks in part to a low chopping frequency, the PMC-25 accelerated as smooth
as cream. I could literally move the car by half-centimeters using only the
accelerator. It ran cool; never broke a sweat even when climbing hills, and
that was without any kind of auxiliary heatsink. (Granted that the entire
case was a heatsink.) Not to say this is impossible with a 15kHz or higher
PWM, just that it is often easier to do with a lower frequency.
Curtis controllers are more like Ford Escorts than BMWs. They're not high
performance units, but they're entirely serviceable for the average person
who is building a practical commuter and not a sports car or dragster.
They're available today, and probably will be tomorrow. They have proven
their utility in hundreds, probably thousands, of conversions. Because they
are similar to Curtis's golf car controllers, there will most likely be
someone who can repair yours for you, at a reasonable cost, if it fails 5 or
10 years from now.
If you can afford a Zilla, and are willing to wait for it, then I say go for
it. It is, by all accounts, a fine product. But if you choose to buy a
Curtis instead, don't let anybody make you ashamed of your choice. It's a
decent, competent controller. Take the money you saved and invest it in a
better, smarter charger, one that will buy you longer battery life and lower
long-term operating costs.
David Roden - Akron, Ohio, USA
EV List Assistant Administrator
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--- Begin Message ---
So I finally saw the WKTEC car movie this afternoon down in Greenbelt
MD. Good movie without a doubt; I was impressed with the style the
research, and the commentary.
However in thinking about it, they forgot to add one suspect to the lineup:
The EV1.
The EV1 was a beautiful car, no doubt about it. But maybe some of the
fault can be laid to rest with it. It was an extremely complex car,
hand-built, with a million refinements and new bits of technology. It
looked sleek, but at what cost?
Before they made the EV1, they made the Dolphin series of cars. I have
one; it's the same controller. But instead of building a super-complex
car, they pulled a Prizm off the line, bolted the motor to the stock
transmission, put a battery clamshell in the middle, and stuck a
Magnecharger in the back. Not that complex, not that expensive, and 95%
of the car is stock. Even has AC, heat, regen braking, power steering,
the works...
It's drawback? It only goes 40 miles instead of 80. But it seats five,
looks like a normal car, can carry luggage, and probably costs only
about 10k more to build. It's an evolution; the EV1 was a revolution.
Perhaps the expectations of trying to sell a concept car as a production
car was what doomed the electric car. If they had taken a Dolphin Prizm
and put in 100ah NiCD batteries, they would have a 100 mile range car.
One that you could sell to families, people who had to haul things in
trunks, normal people.
Instead, everyone paid attention to the EV1; and by doing so they missed
the RAV4, the minivan, the S10's, and the Prizms.
Imagine if Hybrids had stopped with the Insight. It's a total new
technology marvel like the EV1. It gets 80+mpg. It's cute. But it only
seats two, it has no space for things. It doesn't seem to sell very
well. By contrast, Toyota made a normal dull 4 seater with a hybrid
system that only gets 50mpg and it sells like hotcakes. Not because it
is better; it's not in terms of sheer performance. But it will seat
four, carry a load in the trunk, and feels like a normal car. Same with
the Prizm.
One can only wonder...
Chris
--- End Message ---
--- Begin Message ---
Hi Cory,
I apologize that I do not have exact numbers.
The particular VFD is in the back of my garage, behind a
stack of junk that will take me too long to pull out, also
my controller did not open up far enough to be able to
read the capacity of the bank of electrolytes, but let's
throw some assumptions at it and see where we end up:
I have a tiny VFD with a 1500uF 400V capacitor that is
about 2" in diameter and 6" long.
My controller is about 2' long and has 8 elco's in one row
so that is about 3" diameter per capacitor and the length
is another swag, but let's say it is not shorter than the
1500uF one.
Since 1.5 times the diameter packs 2.25 times the surface,
the capacitors in my controller are likely to be at least
3300uF if not more - I suspect them to be 4700 but lets stick
with the minimum for now.
The configuration of the 8 in two series banks of 4 parallel
makes the total voltage and capacitance both double.
So 800V and 6600uF minimum for the total.
Since this is an AC drive with an inaudible (Sine) waveform,
I guess that they switch at least at 20 kHz if not higher.
This means that maximum AC current will likely be at 50%
duty cycle, which is 25us on and 25us off. This gives us
the time base. The max current my controller cranks out
draws 200A from the batteries, I suspect that they limited
the controller in SW.
Now the formula to find the voltage ripple is:
I x t = V x C and solving for V:
(I x t) / C = V entering the values we found above:
(200A x 25us) / 6600uF =
200 x 25 x 10^-6 x 150 = 0.75V
So my controller likely has less than 1V ripple at max
switching power at its current 312V pack.
I tell you that this capacitor bank is totally absorbing
the switching effect and my batteries see a constant
current being drawn by the controller with a very small
ripple due to the size of the capacitors, while they supply
the energy for the pulses to my motor.
I trust Otmar that he has optimized the Zilla to include
capacitors large enough to filter the ripple to a small
enough factor that also there the batteries essentially
see a constant current, although at 1000A the ripple
may be larger than in my case, still I would expect it
to be only a few percent of the DC current, so the
batteries are not affected significantly.
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
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Take your network further http://www.proxim.com
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Cory Cross
Sent: Saturday, October 21, 2006 10:51 PM
To: [email protected]
Subject: Re: Current multiplication, was: EV controllers? Practical
parame ters
Hi Cor,
The first purpose of capacitors is to protect the switching
elements. In order to feed the motor they must be capable of around
250Arms (in your case), which I doubt, in addition to needing enough
capacitance inversely to PWM frequency and minimum duty cycle. Do you
have part numbers and/or specs on those capacitors?
None of the golf cart controllers have enough capacitance. Judging
by the size of the Zilla, it does not either. I bet the VFD capacitors
are for power faction correction.
Cory Cross
Cor van de Water wrote:
>Hi Cory,
>
>Good controllers have large capacitors at the battery input
>for this very reason - to smooth out the short pulses into
>a constant battery current with very small ripple.
>It is indeed a measure of how good the controller is, with
>most SCR controllers this smoothing is not present, so they
>will peak the same batetry current as the motor sees, making
>the Peukert effect take a larger toll, that is why Lee
>suggested to add large capacitors at the input of an SCR
>controller, to increase range by drawing a constant current
>from the batteries instead of short high peaks.
>
>So - it depends on the controller!
>
>BTW, in my 700V 250A AC controller more than half the volume
>of the controller is taken up by 8 huge capacitors.
>I think they are switched as 2 series groups of 4 parallel
>if they are using standard 400V electrolytes, but I have
>not cut that deep into my controller yet.
>
>I have a salvage VFD (Variable Frequency Drive) that is
>specified for 600V 3 phase and it also has 2 banks of
>capacitors switched in series to take the voltage.
>
>Note that the higher the switching frequency, the smaller
>the capacitors can be, as long as their internal resistance
>is low enough to take the AC current of the charging and
>in particular the discharging peaks.
>
>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 eFAX: +1-610-423-5743
>Take your network further http://www.proxim.com
>
>
>-----Original Message-----
>From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
>Behalf Of Cory Cross
>Sent: Saturday, October 21, 2006 5:18 PM
>To: [email protected]
>Subject: Re: Current multiplication, was: EV controllers? Practical
>parameters
>
>
>Cor van de Water wrote:
>
>
>
>>The modern switching controllers allow the *motor* current
>>to me many times larger than the *battery* current, in
>>particular at low motor RPM.
>>
>>
>>
>>
>Nitpick -- they allow AVERAGE battery current to be lower. I recently
>requested information (on the evtech list) on any experiments to see if
>the high-frequency, low-duty-cycle draws consume at a Peukert's rate of
>the average or motor currents, but there don't appear to be any studies.
>
>Cory Cross
>
>
>
>>How? Simple - by sending battery voltage (and current) to
>>the motor for a very short period of time, which increases
>>the motor current quickly due to the low motor voltage at
>>low RPMs.
>>Then the majority of the time the controller disconnects
>>the battery from the motor, but since the motor acts as
>>an inductor, the current keeps flowing for a while, slowly
>>ramping down. The current flows through special diodes in
>>the controller output, which prevent the output voltage
>>
>>
>>from going negative by the motor current pushing through.
>
>
>>In low RPM situations the batteries may supply current
>>only 20% of the time, while the motor current loops around
>>through the diodes for the other 80% of the time.
>>Say the motor current is 500 Amps average, then the average
>>battery current is 20% or 100 Amps.
>>When you think this is impossible because energy cannot be
>>multiplied, it must come from somewhere then please think
>>about it as a transformer: low current and high voltage go
>>in at one side, high current at low voltage come out.
>>The above example may have a 200V battery pack while the
>>average motor voltage is around 36V.
>>(Yes, there is some loss in the controller and you can see
>>that the current goes from 20% to 100% while the voltage
>>goes from 100% to almost 20% - without loss it should be 40V)
>>
>>Indeed - current multiplication is only effective when RPMs
>>are low, but then is exactly when you need it!
>>
>>The motor current continuing to loop around can be thought of
>>as a wind-up toy: you can give it a quick turn, after which
>>is will run for a while, slowly losing speed. If you give it
>>a quick turn from time to time, it will continue going, just
>>like the controller giving the motor short bursts of battery
>>voltage to kick up the motor current, in between it will slowly
>>decay but as long as the ripple is small you will have a smooth
>>running motor at a much higher torque than the battery current
>>would suggest, because most current just loops around in the
>>motor and controller output diodes.
>>
>>Hope this clarifies,
>>
>>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 eFAX: +1-610-423-5743
>>Take your network further http://www.proxim.com
>>
>>
>>-----Original Message-----
>>From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
>>Behalf Of Dave Wilker
>>Sent: Saturday, October 21, 2006 12:26 PM
>>To: [email protected]
>>Subject: Re: EV controllers? Practical parameters
>>
>>
>>The only way I know of is a step-down transformer.. Is that what you mean?
>>Or do you mean torque multiplication?
>>
>>
>>
>>David C.. Wilker Jr.
>>USAF (RET)
>>----- Original Message -----
>>From: "Ryan Stotts" <[EMAIL PROTECTED]>
>>To: <[email protected]>
>>Sent: Saturday, October 21, 2006 11:44 AM
>>Subject: Re: EV controllers? Practical parameters
>>
>>
>>
>>
>>
>>
>>>Steve Condie wrote:
>>>
>>>
>>>
>>>
>>>
>>>>current multiplication
>>>>
>>>>
>>>>
>>>>
>>>Hows that work?
>>>
>>>
>>>
>>>
>>>
>>
>>
>>
>>
>
>
>
--- End Message ---
