EV Digest 5042
Topics covered in this issue include:
1) Re: Pic vs mc68HC05
by Lee Hart <[EMAIL PROTECTED]>
2) Re: I want to build a PWM DC motor controller
by Lee Hart <[EMAIL PROTECTED]>
3) Re: I want to build a PWM DC motor controller
by Lee Hart <[EMAIL PROTECTED]>
4) Re: I want to build a PWM DC motor controller (LONG)
by Lee Hart <[EMAIL PROTECTED]>
5) Re: Reverse for Direct Drive (was S10 reverse)
by Doug Weathers <[EMAIL PROTECTED]>
6) RE: refractometer vs hydrometer...
by "Roger Stockton" <[EMAIL PROTECTED]>
7) Re: Competition for Jerry's Freedom EV?
by Michael Hurley <[EMAIL PROTECTED]>
8) RE: refractometer vs hydrometer...
by "Roger Stockton" <[EMAIL PROTECTED]>
9) RE: I want to build a PWM DC motor controller
by "Roger Stockton" <[EMAIL PROTECTED]>
10) Re: If I build it, will it perform? Or, do I need to go with "more power"
by "David Roden" <[EMAIL PROTECTED]>
11) Re: If I build it, will it perform? Or, do I need to go with
"more power"
by "John G. Lussmyer" <[EMAIL PROTECTED]>
12) Re: Reverse for Direct Drive (was S10 reverse)
by Doug Weathers <[EMAIL PROTECTED]>
13) Re: Reverse for Direct Drive (was S10 reverse)
by James Massey <[EMAIL PROTECTED]>
14) Re:S10 reverse
by James Massey <[EMAIL PROTECTED]>
15) RE: Reverse for Direct Drive (was S10 reverse)
by "Dave Davidson" <[EMAIL PROTECTED]>
16) Madman is back from MG
by "Roderick Wilde" <[EMAIL PROTECTED]>
17) Re: Reverse for Direct Drive (was S10 reverse)
by "Peter VanDerWal" <[EMAIL PROTECTED]>
18) power master or deltran battery chargers
by paul wiley <[EMAIL PROTECTED]>
19) Re: refractometer vs hydrometer...
by Dave <[EMAIL PROTECTED]>
20) Re: Tax Credit for Conversion
by mike golub <[EMAIL PROTECTED]>
21) Re: Reverse for Direct Drive (was S10 reverse)
by John Wayland <[EMAIL PROTECTED]>
22) Re: If I build it, will it perform? Or, do I need to go with "more
power"
by Dave <[EMAIL PROTECTED]>
--- Begin Message ---
Danny Miller wrote:
> The PIC is quite C-friendly... BASIC Stamp is pretty much a marketing
> joke. There's zero reason to be running externally stored, interpreted
> code. The PIC can store all the code on-part.
You're experience is a bit limited, Danny.
PICs were optimized for assembly-level programming, and have very
limited stacks, small RAMs, and separate program and data memory spaces.
You can program in C only because a C compiler can produce assembly code
for it.
In the context of writing safe code, using a high-level language like C
is counter-productive because the programmer loses track and control of
what is really going on.
For example, one of the requirements for safe programming is that you
must tolerate memory errors. So, you store data redundantly in 3 RAM
locations, and compare them. If one doesn't match the other two, ignore
it. If the memory error persists, lock down the product so it won't work
any more.
Programming in a high-level-language blocks control over this. The
standard run-time libraries won't do this kind of checking. Even if you
wrote your own library, the nature of subroutine calls and returns will
still depend on perfect RAM to work correctly. You can avoid this
problem in assembler (don't *DO* subroutine calls), but not in C!
The BASIC Stamps are worthless for safe, reliable processing. They are
running a high-level language (BASIC) which has the same problem as C or
any other. But the Stamps do have useful features for other
applications. They are easier to use for beginners with no programming
experience. Their documentation is writtern for ordinary people, not
professionals. They include features you can't get on-chip, such as
voltage regulators, bypass capacitors, good power-on-reset circuits, and
RS-232 interfaces. The Stamps are PICs on a PC board that comes with all
the extra parts you'd need to make a working system.
With regards to the 68xx class micros vs. PICs, I've had *far* more
trouble getting the 68xx micros to work safely in high-noise
applications than PICs. It was the Motorola 68HC05 that had the
factory-test mode that it could accidentally fall into from noise, and
then couldn't be gotten out of except by removing power. The 68xx
architecture also combines memory and I/O in a single programming space;
this made it virtually impossible to prevent program errors from
inadvertently writing to outputs.
We did *extensive* testing of many brands of micros, and the PICs were
the most noise-immune and best able to be "tied down" by programming
techniques to prevent false operation. Now, this testing was done about
10 years ago, when some of the newer micros didn't yet exist. However,
the trend is to make newer micros WORSE than the older ones with respect
to noise and safety, by shrinking chip sizes, increasing speed, lowering
supply voltage, and increasing the number of parts on-chip. The micros
with the very highest safety and noise immunity (and still used in
spacecraft, medical, and other vital applications) are very old parts
like the 1802.
--
Lee A. Hart 814 8th Ave N Sartell MN 56377
[EMAIL PROTECTED]
--- End Message ---
--- Begin Message ---
Stefan T. Peters wrote:
> I would say that due to the nature of our physical universe, the
> same astronomically large number that is *theoretically* possible
> in digital circuits is *theoretically* present in analog.
This is incorrect. Take a simple application like an adder. If you do it
digitally, it used thousands of individual transistors, any one of which
can fail shorted or open. When one transistor fails, only certain sums
will be incorrect; others will still be correct. To find a bad
transistor, you have to test virtually every combination of sums and
check the result for errors.
An analog adder consists of a few resistors and an amplifier. There are
about 1/100th as many parts, so to start with, it is 100 times more
reliable. But there are more failure modes per component (analog parts
that change value also cause errors, instead of just being good/bad as
in digital circuits). So overall, the analog circuit is perhaps on 10
times more reliable.
In analog, all parts are used all the time. When a part does fail, it
causes *all* sums to be wrong; thus it is much easier to test.
> You only have an "astronomically large" possible numbers of failure
> with a unknown code set.
Even a tiny microcontroller with only 1k bytes of storage has 8,192
possible locations for a memory failure. Each location can be stuck high
or stuck low. Thus, you have 16,384 failure conditions to test for.
You might say, "Well, I'll include a subroutine that checksums memory."
That will catch perhaps 90% of the 16,384 possible failures. But the
checksum program itself is in memory; what if the error lands in the
checksum program itself? You'll need a separate way to test its memory.
> Use a micro with fused running parameters. No software access, period.
Except that reprogrammable flash or EEPROM memory is more popular;
permanently writable configuration memory is getting rare.
> If enough of the same parts fail in *any* electronic circuit, stuff
> goes nutty.
Yes; but you can design circuits so all possible "nutty" behaviour is
still safe.
>> 3. Programmers leave a "trap door" routine in the code...
> Now that is just PEBCAK (Problem Exists Between Computer And Keyboard).
It is hard to write software that you can *prove* is correct. All too
often, code is thrown together in a hurry, and no one double-checks it.
So bugs *do* commonly get left in.
>> 5. The micro's clock fails...
> Which means nothing happens. Nothing functions. If it does, change the
> interface circuit.
If the micro turns on a critical output, and THEN the clock stops, it
remains "hung" with a live output! Software has no control over it. Some
micros will not even reset without a clock, so even a watchdog can't
stop this failure. And, every micro I know of with an internal clock has
a "stop the clock" mode that the software can set.
They don't put "gotchas" like this in the data sheets; you have to try
it yourself to be sure the micro you picked doesn't have this failure
mode.
> You said "engineers can design fail-safe circuits, where every known
> failure mode leads to a safe condition." So they can design CPU clock
> and interface circuits in the same way, right?
They can; but they rarely do. It is easier to put a note on the data
sheet saying "not for use in safety-critical applications".
> I don't pretend to know how to do that, which is why I use well
> tested, expert-designed clock and interface circuits.
Unless it specically says it is fail-safe, it isn't! I don't know of any
standard micro or clock generator that is fail-safe. You have to design
and build your own.
>> 6. Micros usually have "write-only" locations for I/O, which can't
>> be read to verify that they are actually working.
> I would never try to read my outputs. If you need to monitor what
> you just did, use an independent data source
Yes, you normally use separate inputs to check your outputs to see if
they work. But, you will find lots of products where the engineer "saved
a pin" by not bothering to do this. Or, the output he wanted to monitor
in internal to the microcontroller, so it can't be read directly (for
instance, the outputs that control bank-selectable memory, or set modes
for internal peripherals).
>> 7. Most micros blindly continue to execute programs even when the
>> chip is too hot or too cold, the supply voltage is too high or
>> too low, or the clock frequency is out of bounds.
> Use one with thermal shutdown circuits. Voltage brownout circuits.
> Use a voltage regulator with overvoltage and cpu reset.
There are no micros that check their supply voltage, temperature, and
clocks for out-of-bounds conditions; some or all of these functions must
be done externally. Most designers save money and don't bother.
>> 8. An output bit gets stuck low due to being static zapped, or
>> other hardware failure.
> Make sure that only "output high" is the condition for external
> circuit activation.
This problem occurs no matter whether high or low is the "active" state.
Outputs can just as easily stick high or low.
One way to deal with this is to require an *AC* signal on the pin for
"active". The software has to actually be running to produce this AC
signal (and it has to be of the right frequency and duty cycle).
Another way is to have two outputs to control one device. Each output
also has an input to test its status. Turn on one output, and check to
see that it works; then turn it off. Turn on the other output, check to
see that it works; then turn it off. Now turn on BOTH outputs to
activate the load. Turning off EITHER output will disable the load.
Or, you can have a watchdog circuit that is watching for a stuck-on
output, and cuts power to the micro if it happens.
>> 9. Most micros have "factory test" modes so they can test the chip
>> even with some customer's program in it.
> Don't use one of those.
Except that the manufacturer won't tell you about these modes (unless
you drag it out of them). Every time I've found them, the manufacturer
would deny such a mode existed until AFTER I proved it was there! :-(
>> 10. High-current pulses on a micro's output... can cause "latch up"
> Now *this* is a well-documented, sometimes unavoidable (from a
> programmers perspective) event. But the answer is the same as with any
> circuit, analog or digital. Isolate, buffer, and protect.
Latch-up is very common in ICs, but not in most discrete circuits.
> It's much easier for *you* to build fail-safe hardware circuits.
> Which means it is also much easier for *you* to build fail-safe
> micro circuits.
What I'm saying is fail-safe design is easier with hardware circuits,
period. Add a micro adds more failure modes and more complexity, both of
which complicate things enormously. A large company may have the reasons
and resources to proceed anyway; but the lone hobbyist probably doesn't.
So, he's better off avoiding micros for the fail-safe parts of the
design.
> I'd say all things are equal, circuit are circuits, professionals
> are professionals, amateurs are amateurs. Encouraging the casual
> electronic hobbyist to attempt the safe design of a large analog
> motor speed controller is the same as encouraging a casual
> programming hobbyist to code a micro doing the same thing. Not a
> great idea either way. But they both are going to do it anyways,
> so you might as well help make sure both are safe by lending a
> hand with what you are an expert in.
Yes, I agree with you.
Step one is to make the casual builder AWARE that there is a problem.
He's likely to charge into it blind, not knowing (for example) that
transistors fail "on", or that micros "crash". Some will just ignore the
warnings, and proceed anyway. They are the ones that will create buckets
of blown parts, or make new exits in their garage walls. They may still
succeed (and may even have a lot of fun and excitement doing it). But
more likely, they will get discouraged, or hurt, or give up.
Step two is to discuss HOW to avoid these pitfalls. This list is a great
source for this kind of information. In fact, that's what we are doing
in this thread!
--
Ring the bells that you 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
[EMAIL PROTECTED]
--- End Message ---
--- Begin Message ---
Stefan Peters wrote:
> Hmmm... would simply cutting the connection to the gate when you let
> up on the throttle be sufficient?
MOSFET and IGBTs can turn *on* when you disconnect their gate! At the
very least, you need to install a resistor between gate and source
directly at the package. This will turn it off even if the wire between
the transistor and its driver breaks.
> Use a "throttle interlock" connection from a microswitch that
> energizes a N.O. relay (maybe solid-state?) whenever the gas is
> pressed.
This is the right sort of thinking. The key is to make your fail-safe
circuit as simple as possible, so it is easier to examine all the things
that might go wrong with it.
The standard approach is to put a microswitch on your accellerator. When
the pedal is released, this switch turns off the main contactor. Even if
the controller goes nuts, this switch and contactor should stop the
entertainment.
A more automated method would be to tape a normally-closed reed switch
to one of your high-current cables. Position it so if the current ever
exceeds the controller's current limit, this reed switch opens. This
switch cuts power to the main contactor.
If you don't trust the contactor to turn off (i.e. you cheaped out and
don't have one big enough to handle a worst-case event), then you can
use a crowbar circuit instead. A crowbar is a switch, contactor, SCR,
etc. that turns on to SHORT the battery if something goes wrong. The
short blows a fuse to stop the entertainment. It is much easier to get a
switch, contactor, or SCR that can be guaranteed to turn on rather than
off. For example, you have a normally-open reed switch taped to a
battery cable; overcurrent makes it close, which turns on an SCR to
short the battery and blow a fuse.
> I just want to see if something else besides the seemingly sacred
> PWM is a possibility for DC series motors in a traction application.
PWM just means Pulse Width Modulation; i.e. cyclic on/off control rather
than a huge adjustable resistor. PWM isn't the controller itself; the
controller is a "converter" that happens to use PWM as one of its
components.
Look up circuits for "converters" -- you will find that the are dozens,
perhaps hundreds of different ones. Only a few have been used in EVs;
mainly the "buck" converter and 3-phase H-bridge. But many others are
feasible and perhaps even practical. They just haven't been explored
nearly as much.
--
Ring the bells that you 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
[EMAIL PROTECTED]
--- End Message ---
--- Begin Message ---
Steve Arlint wrote:
> 1. What is the line between a hobbyist and an engineer?
You don't need a degree to be an engineer. A lot of "engineering" is
about one's attitude, and the approach one takes to problem-solving.
The famous engineer Charles Proteus Steinmetz said, "Amateurs create
problems. Engineers solve them!"
Are you just fooling around, playing, not bothering to measure results,
not doing any real research, and don't really care if it works or not?
Will you give up if you don't succeed right away? Are you mostly
concerned with appearnce, or people's opinions? Then you are a hobbyist.
Are you serious and determined to solve the problem, even if it turns
out to be hard or expensive? Are you willing to study, and learn new
things to make it work? Are you methodical and logical? Do you measure
and document your results? Are you more cuncerned with results, and not
appearances or other people's opinions?
> 4. The best advice I can give on building a motor controller is don't
> go for the 192V 1200A project to begin with.
> 5. One other thing to do is don't work alone.
Excellent advice!
--
Ring the bells that you 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
[EMAIL PROTECTED]
--- End Message ---
--- Begin Message ---
On Dec 31, 2005, at 9:28 AM, John Wayland wrote:
Hey list folks, any creative but light weight reverse ideas for a high
powered direct drive drag - street car?
Instead of a reversing contactor, how about a big beefy reversing knife
switch? Would that provide less loss than the reversing contactors?
Or instead of the knife switch, how about another one of those
emergency disconnects you've got in the cabin? Take it out, turn it
around, and plug it back in, and you've got reverse (assuming
everything was wired up correctly). This idea would remove all the
bare metal of the knife switch.
How about having a small idler wheel on a hydraulic strut in front of
each rear tire? Extend the strut, and the idler wheel is forced under
the tire. Now when the rear wheels turn, the idler wheels turn the
opposite direction and move the car backwards.
Is there a way to make the rear end reverse, perhaps with a yank on a
cable?
See Ya.....John Wayland
--
Doug Weathers
Bend, OR, USA
http://learn-something.blogsite.org
--- End Message ---
--- Begin Message ---
Dave [mailto:[EMAIL PROTECTED] wrote:
> I was all set to order a misco refractometer because I was
> getting tired of spending 20-30 minutes once or twice a day
> to check my batts...
Once or twice a day??? Why are you checking them that often?
> Then I thought to ask my wife who has used refractometers in
> the lab, She said her experience has been they are difficult
> to read and the dilenation is not sharp more gradual from
> light thru grey and then dark requiring eperience/guesswork
> to interpolate the proper reading.
>
> So is anyone currently using a refractometer? How
> simple/difficult is it to read?
I use a MISCO refractometer regularly and find it to be a *huge*
improvement over a hydrometer.
It is very simple and easy to read, and the delineation is sharp unless
the sample glass/window gets contaminated. (I have found one particular
brand of battery that gets a black tarry contaminant in the electrolyte
that the manufacturer states is a mold release agent from the
manufacture of the plates, and if some of this contaminates the sample
window, I have to give it a wipe with isopropyl alcohol before sampling
the next cell otherwise the delineation between the light and dark areas
will be poor.)
Perhaps your wife hasn't used a MISCO refractometer (they have an
illuminated eyepiece that may make them more readable than others)?
> One other downside it seems to me would be stratification of
> the acid in the battery. with a hydrometer I take my reading
> on the 3rd bulbful. whereas the refractometer uses only a
> drop or two of liquid and would only be reading the very top
> layer of acid...
This is true, however, if you take your sg readings shortly after the
batteries finish charging, the electrolyte should still be fairly
uniform due to the mixing action of the end-of-charge gassing. Or, rock
the car a bit on its suspension to stir things up a bit before checking
the sg if you want to be doubly sure.
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
At 5:52 AM -0500 on 12/29/05, jerryd wrote:
Michael is correct about building a one
off fiberglass on shape foam body as very labor intensive
and probably why neither the Doran or any of the Riley
designs have ever been finished.
Ummm.. Jerry, that isn't quite what I said. I said the plans were
largely incomplete and therefore very hard to follow. In fact dozens
of Riley's machines have been made and finished all over the world.
To my knowledge only two Dorans have ever been finished (Rick's
original and EV3PO). The difference? Riley's plans are thorough and
complete, telling you exactly where to put what when and simple to
understand and build. The Doran plans are really just guidelines. The
related Dolphin Vortex, while the plans are very thorough and
complete is not simple in the slightest and requires much more work,
so only four or so have been made.
Though Riley has sold over 40,000 plans sets!!! Sadly they could
have easily been designed in bent flat panel construction and
finished in a couple weeks
instead of many times yrs, if at all.
I think the major problem with that is it often makes something which
is obviously wooden and "weird" looking. It usually doesn't have the
compound curves and smooth lines of a production car. Most people
don't like that kind of look. FRP/Urethane composite may well be more
work (I've done neither so I can't comment), but it produces
something more in line with what people think a finished vehicle
should look like.
--
Auf wiedersehen!
______________________________________________________
"..Um..Something strange happened to me this morning."
"Was it a dream where you see yourself standing in sort
of Sun God robes on a pyramid with a thousand naked
women screaming and throwing little pickles at you?"
"..No."
"Why am I the only person that has that dream?"
-Real Genius
--- End Message ---
--- Begin Message ---
Bob Bath [mailto:[EMAIL PROTECTED] wrote:
> I _was_ using a refractometer, and am now back to a
> hygrometer, due to incomplete charging.
Can you explain why incomplete charging would cause you to switch from
one method to the other?
Stratification will result in the lighter (lowest sg) electrolyte
remaining at the top of the cell, so if stratification were an issue for
you, it would *not* result in incomplete charging going undetected when
using a refractometer. Indeed, since stratification would result in the
refractometer readings being *lower* than if the electrolyte were more
uniformly mixed, you would detect incomplete charging even sooner with
the refractometer.
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
Mark Hanson [mailto:[EMAIL PROTECTED] wrote:
> All the presently sold motor speed controls use a
> uP or uController.
Not true; the Curtis series motor controllers are all analog.
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
It's hard to say whether your project will outperform your earlier ones
because you don't say what they were or how they performed.
Others may disagree, but IMO, a light car can perform adequately with a
series DC setup and an 84 volt system. The old US Electrical Renaults were
48 volts and could hit around 50 mph in factory trim, IIRC. So you should
be able to get around 55 mph as a top speed, maybe 60, but not much more.
If you can hold weight to around 2200 lb, your acceleration should be
adequate but it won't be a neck-snapper by any means.
As a benchmark, I had a '74 Honda Civic with a 400 amp PMC controller, 96
volts of golf car batteries, and a Prestolite motor - total weight 2500 lb.
It did 0-50 in about 20 seconds (estimate, I never timed it). It reached a
top speed of something over 65 mph, but it took a while. In conservative
city driving, it would do a reliable 40 miles of range, with an absolute max
of almost 65 miles while risking batteries on a hot day. Many people here
would call it a slug, but it was adequate for my needs.
You are likely to have problems with pack balance if you use a different
type and brand of charger on part of your pack. It'll be worse if you drive
after partial charges. I recommend that you either buy an 84 volt charger,
or go with a 72 volt pack.
Note though that the 10a, 72v charger you cite is a fairly low power
charger. It may well be the limiting factor on your daily range, rather
than the battery, because it's likely to need 15 hours or more to bring up
an 80% discharged pack. I'd estimate you'd get about 3 miles of range per
hour of charging (assuming you actually charge to 100% each day). Thus if
you have only 8 hours to charge each day, your effective daily range is 24
miles.
You might do better (and possibly for less money) with a couple of used 36
volt golf car chargers, one for each half of the pack.
>From what I understand, Sam's Club buys golf car batteries from whomever
bids lowest that year (or quarter). You might get Exide, Johnson, Trojan,
or US Battery product, or some other brands I've forgotten now. I'm not
much a fan of Exide, but whatever differences exist among the other brands
are probably less significant in determining life than how you care for
them.
David Roden - Akron, Ohio, USA
EV List Assistant Administrator
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--- Begin Message ---
At 08:52 AM 12/31/2005, [EMAIL PROTECTED] wrote:
1. Good acceleration - 0 - 45 MPH in ~15 sec or less (faster is better!)
2. Speed - Capable of 55 MPH, even though I don't plan to take it over 45 MPH
3. Hill climbing - We have them, and it needs to be able to make it up a
"decent grade" at 35 MPH
4. Range - 15 miles round trip - same route every day 25 - 45 MPH city
traffic. Stop signs about every 0.75 - 1 miles. Actual mileage =
6.2 miles each
way, but 15 miles gives me a buffer for stopping at a store on the way home.
5. Late model - parts still available for at least the next 5 years.
Other than the price you mentioned, a Corbin Sparrow meets these
requirements easily. (Much better performance though!) You can
sometimes find used ones in the 5K-8K range.
--
John G. Lussmyer mailto:[EMAIL PROTECTED]
Dragons soar and Tigers prowl while I dream....
http://www.CasaDelGato.com
--- End Message ---
--- Begin Message ---
On Dec 31, 2005, at 11:40 AM, Doug Weathers wrote:
Or instead of the knife switch, how about another one of those
emergency disconnects you've got in the cabin? Take it out, turn it
around, and plug it back in, and you've got reverse (assuming
everything was wired up correctly). This idea would remove all the
bare metal of the knife switch.
Sorry, dumb suggestion. You'd need two different plugs, one wired for
forwards and the other wired for reverse.
--
Doug Weathers
Bend, OR, USA
http://learn-something.blogsite.org
--- End Message ---
--- Begin Message ---
At 09:28 AM 31/12/05 -0800, John Wayland wrote:
Hello to All,
<snip>
Hey list folks, any creative but light weight reverse ideas for a high
powered direct drive drag - street car?
Hi All - and Happy New Year to those on the list using the standard western
calender.
OK, if I understand correctly, White Zombie has a pair of motors siamesed
together, with the commutators at oppsite ends to each other. This would
imply that one motor is running "backwards" to the other. I believe that it
is wired all with N.O. contactors, to do the series/parallel shift.
Something like:
o--o
[M+]-|----[F1]--[A1]-|-o o-|
| | C1a |
___| o--o | |
| |---o o----| |
| o--o | C2 |
|--o o-|-[F2]--[A2]-------|-[M-]
C1b
C1a, C1b being the paralell contactors, C2 being the series contactor. F1
being motor 1 field, A1 being motor 1 armature, etc. This is where my
thinking is coming from. I think this would only work properly for a pair
of motors ganged up like the Zombies' are, both doing equal work all the time.
How about wiring the field of the "front" motor in series with the armature
of the "back" motor and vice-versa, and then using a smaller contactor to
connect up one motor to its' "own" armature for reverse?
Forward wiring remains almost the same (note the F1/F2 change)
o--o
[M+]-|----[F2]--[A1]-|-o o-|
| | C1a |
___| o--o | |
| |---o o----| |
| o--o | C2 |
|--o o-|-[F1]--[A2]-------|-[M-]
C1b
Then to get reverse, there is an extra contactor, putting F2 in series with
A2:
_________________
| |
| o--o |
[M+]-|-[F2]-|-[A1]-|-o o-| |
| | C1a | |
____| o--o | | |
| |---o o----| ____| |
| | C2 | |
| o--o | | |
|-o o-|-[F1]-|-[A2]-|-|-[M-] |
C1b | o--o |
|----o o-------|
C3
C3 being the reversing contactor, would only need to be a 250A or so
contactor, since it only carries reverse current, adds two extra wires in
the motor bay, plus four extra wires along the sides of the motor pair to
link the F1/A2,F2/A1 terminals.
How's that for a "creative but light weight reverse idea"?
Of course, I may have the underlying theory wrong, but worth thinking about.
Regards
James
--- End Message ---
--- Begin Message ---
At 09:49 AM 31/12/05 -0500, Dennis Berube wrote:
<snip> Reverse a must can go through a
standard reversing contactor arangement or, can I use a small starter motor
through a ring gear setup on my ge drive motor? This setup could be made very
easy,only adding 9lbs.
Hi Dennis and all
Electric starter motors are designed to burn out after something like 30
seconds, since if your average ICE hasn't started by then the driver will
have let off the starter. How long do you need to reverse for, and are you
going to need to reverse on a steep hill?
How about an air/starter-motor like is used on trucks? It would have a
short overall life, but wouldn't burn out like an electric starter would.
May not have enough air reservoir on board to make it practical.
Single motor, I assume, so no way to implement a trick like I suggested for
John Waylands' car? If so I'd go with the reversing contactors, but keep
the ones carrying reverse current small (seperate contactors, based on John
Waylands comment about spring contact pressure).
Just my $0.02 from the peanut gallery
James
--- End Message ---
--- Begin Message ---
How about taking an idea from the electric bicycle adapters? Put a small
motor with a small wheel that you can pull against a tire to move the car
backwards? Not too elegant or efficient, but you only need to move the car
a few feet.
Dave
Hey list folks, any creative but light weight reverse ideas for a high
powered direct drive drag - street car?
See Ya.....John Wayland
--- End Message ---
--- Begin Message ---
I just talked to Rich a while ago and he has landed safely back in the state
of Washington and is heading home. Be expecting some great stories from him
and Shawn.
Roderick Wilde
"Suck Amps EV Racing"
www.suckamps.com
--
No virus found in this outgoing message.
Checked by AVG Free Edition.
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--- End Message ---
--- Begin Message ---
> Hey list folks, any creative but light weight reverse ideas for a high
> powered direct drive drag - street car?
How about a small reversing motor and a sprague clutch?
--
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 ---
Before i invest in another charger, any thoughts on the powermaster or Deltran
high freq charger? My pack is 48 volts.
Thanks
Paul
---------------------------------
Yahoo! Photos
Ring in the New Year with Photo Calendars. Add photos, events, holidays,
whatever.
--- End Message ---
--- Begin Message ---
Roger Stockton wrote:
Once or twice a day??? Why are you checking them that often?
Yeah I know it's probably anal but I'm a newbie and this is a brand new
pack and I'm still getting familar with it and battery maintenance in
general. The first dozen cycles I checked the SG after charge and after
dis-charge just so I could see what was going on as quickly as
possible. Turned out to be a good thing I did too because I had a cell
go bad in one. And got it exchanged with no cost and no hassle other
than pulling it.
I use a MISCO refractometer regularly and find it to be a *huge*
improvement over a hydrometer.
Well now you have me reconsidering, again. ;^)
Perhaps your wife hasn't used a MISCO refractometer (they have an
illuminated eyepiece that may make them more readable than others)?
She works in a lab and used a large expensive stationary model
refractometer to measure molecular concentrations. Probably not valid
comparison at all... sounds like it has a light source and uses the dual
microscope style eyepieces.
(Stratification) This is true, however, if you take your sg readings shortly
after the
batteries finish charging...
But if you do that you are measuring a surface charge that will
dissapate resulting in a higher than actual reading. ???
I wonder how much jostling of the car would be necessary to mix up the
batt acid...
thanks,
dave
--- End Message ---
--- Begin Message ---
What's the tax form number?
--- [EMAIL PROTECTED] wrote:
> I was just reviewing the federal tax form and found
> out that they are
> reducing the tax credit for conversions.
> Conversions placed into service in 2005
> (ending today) get a 10% credit. Starting tomorrow,
> the credit is only 2.5%.
> That sure doesn't make me very happy. Also, I see
> that credits offered by my
> home state (Georgia) are not what they used to be.
> They are offering a 10%
> credit as well, but it used to be $2500 a few years
> ago. I seem to remember
> people buying NEVs (basically golf carts) and
> getting them free after the tax
> credit.
>
> Does anyone know the plans for these credits after
> 2006? It seems to me
> (from the federal form at least) that it may just go
> away after 2006. I think we
> should all write congress and try to get this thing
> reversed and back to 10%.
> It may not seem like much, but on $6000 worth of
> conversion parts, I could
> have got a credit of $1200. If I can finish within
> a year, I can only get $750.
> Thats a pretty big deal to me. I was counting on
> the $1200.
>
> Steve
>
>
__________________________________________
Yahoo! DSL Something to write home about.
Just $16.99/mo. or less.
dsl.yahoo.com
--- End Message ---
--- Begin Message ---
Hello to All,
Doug Weathers wrote:
On Dec 31, 2005, at 9:28 AM, John Wayland wrote:
Hey list folks, any creative but light weight reverse ideas for a
high powered direct drive drag - street car?
Instead of a reversing contactor, how about a big beefy reversing
knife switch? Would that provide less loss than the reversing
contactors?
Yes, it would. However....One such knife switch would have to have 4
sets of single pole knives to reverse just one motor section. The
Siamese 8 has dual motor sections, thus, we're now looking at 8 sets of
beefy knife switches. Then, you have to consider that to wire these up,
you'd have to run six fairly long lengths of massive (heavy and bulky)
4/0 cable under the car, then into the car to the switcher. We labored
hours, just getting two 4/0 cables to fit through the tunnel, up into
the stainless steel emergency disconnect mount, and mounted secure to
where they would not be scraped by the fat aluminum driveline...it was
super tight fit that had Tim ready to throw things. Another version
could mount the 8 pole knife switch atop the motor, and use buss bar
connections, then have a rod actuator that would pass through the
firewall to a lever to operate things. This would eliminate all the BIG
cables running from the motor sections and into the car and back, but it
would still be a pretty heavy device, and quite frankly, it would ruin
the present super simple and clean motor install.
Or instead of the knife switch, how about another one of those
emergency disconnects you've got in the cabin? Take it out, turn it
around, and plug it back in, and you've got reverse (assuming
everything was wired up correctly). This idea would remove all the
bare metal of the knife switch.
Again, two motor sections to deal with, and lots of bulky and heavy 4/0
cables with next to zero room to rout them.
How about having a small idler wheel on a hydraulic strut in front of
each rear tire? Extend the strut, and the idler wheel is forced under
the tire. Now when the rear wheels turn, the idler wheels turn the
opposite direction and move the car backwards.
Now this is getting over the top...but it's fun to consider :-)
Is there a way to make the rear end reverse, perhaps with a yank on a
cable?
I wish.
Hey, I appreciate the ideas, keep 'em coming, but consider my
requirements of a clean and sano install that won't obscure the view of
the motor, very heavy current handling capacity, limited room to run
cables through the tunnel (call this next to none), high reliability,
and lastly but very important, low weight.
The rear mounted, 12V reverse motor idea sounds the best so far. Using a
nice, small sized import type starter motor, most of which use aluminum
for the head section, employ quality-made series wound motors, and use a
higher revving motor that's already gear reduced to lower current draw,
along with a gear that mounts to the rear end input flange, seems like
the best way so far.
See Ya....John Wayland
--- End Message ---
--- Begin Message ---
My little Honda (1972) 84v orig. but now 96 appears to satisfy your
criteria. I don't know how long it takes to get to 50mph but it'll do
50-55mph. I live in Seattle city on one of seven hills and find that if
I stay on the main roads I won't have a problem. But I can't take the
shortcuts through the steeper neighborhoods. Just today I drove 8miles
reached a top speed of 50mph usied up 56% of my 100ah pack with the
floor set at 70%. So I'd guess 15miles might be doable. but of course
it depends on both the driver and the route.
ta,
dave
[EMAIL PROTECTED] wrote:
I'm considering my options on the "small car" commuter EV that I was planning
on building. Having owned 3 "poor performing" EVs in the past 6 years, I
don't want to repeat that situation. If if won't perform, I won't build it. My
goals have been and still are:
1. Good acceleration - 0 - 45 MPH in ~15 sec or less (faster is better!)
2. Speed - Capable of 55 MPH, even though I don't plan to take it over 45 MPH
3. Hill climbing - We have them, and it needs to be able to make it up a
"decent grade" at 35 MPH
4. Range - 15 miles round trip - same route every day 25 - 45 MPH city
traffic. Stop signs about every 0.75 - 1 miles. Actual mileage = 6.2 miles each
way, but 15 miles gives me a buffer for stopping at a store on the way home.
5. Late model - parts still available for at least the next 5 years.
I already have the following parts:
1. Series wound 7.2" x 15" fork lift motor
2. GE EV-1B controller - 84 V with 1A bypass (I have no idea what the
continuous rating on the controller is, but I am guessing about 150 A). I wanted to
build my own 144 V / 600 A controller, but I have been talked out of it.
3. Main contactor
4. Other misc parts left over from my other cars
Two options:
First option - "The less expensive car"
1992 Ford Festiva - I actually like the way is looks and low curb weight
manual trans - retain clutch - use 2nd and 3rd gear only
EV-1B controller (150 A cruise, 84 V / 500 A full power for acceleration /
steep hill climbing)
- I realize this controller will reduce battery life because of the 300
Hz SCR switching speed, but maybe I can help it with some caps.
84 V - 14 x 6 V golf cart batteries (Sams Club)
- Dispersed around the car
- 4 in far rear - sunk low through cut out in floor
- 4 center of car behind front seats (remove rear seats) - floor level
- 2 where front pass seat was - floor level
- 4 in front where radiator was - sunk low
- Not the best batteries, but usable. Maybe I'd spring for some T-125's.
Charger
- www.northerntool.com, 72 V / 10 A charger + 1 12 V deep cycle 10 A
charger
Modifications
- I didn't plan to modify the suspension or brakes with only 800 lb of
batteries dispersed around the car, sunk low front and rear, I think it will be
OK with stock suspension and brakes.
Cost (parts only):
$500 - donor car - 1992 Festiva - 130,000 miles - running condition
$200 - batt boxes - home made
$140 - controller + two main disconnect contactors one on the +ve and one
on the -ve (already have them)
$50 - pot box (used)
$50 - main fuse and contactor drivers + other spare parts (salvage lift
parts)
$160 - motor (I already have it)
$265 - motor coupler and mounting plate - my design - material only -
labor not included
$200 - Charger #1
$40 - Charger #2
$125 - 2/0 welding cable + terminals (I'm not sure about this cost)
$770 - batteries - ~$55 / ea including tax
$65 - aux battery
$2565 Total
-$320 Tax credit (12.5% - 10% State of GA + 2.5% Federal for 2006)
$2245 Net cost
Notes:
- NO DC - DC convertor
- Little to no instrumentation (although I can get current reading off the
EV-1, and voltage off the pack)
With all that said and detailed out, I have several concerns.
1. I don't want to build an "electric jalopy". I've owned 3, and have no
need for another.
2. Is the motor at 7.2" undersized to much?
3. Only 84 V ? Can I meet my acceleration requirements with the EV-1B and 1A
bypass?
4. The charger - really may be too slow to recharge 12 miles of range over a
12 hour period. It may not work for that reason.
5. Handling if I don't modify the suspension / brakes.
Second Option:
- 1993 Ford Festiva (last year made), Chevy Metro 2 door (last year
made), Honda Civic hatchback (early 90's)
- 9" Warp or ADC
- 14 x 12 V = 168 V Optima batteries
- 1k Zilla controller
- PFC 20 Charger
- DC - DC convertor
- power steering off aux motor
- bower brakes off vac booster
- retain two front seats - remove others
- sink batts low for low CG center, front and rear - that's a lot of
cutting through the floor.
- e-meter with instrumentation
- some type of suspension and handling upgrades dependent on donor car
Projections:
Acceleration - FAST! - And I would look forward to that!
Top Speed - 80+ MPH
Range - >30 miles
Cost - Parts ~$7500 (Please correct me if I am way off)
The question becomes, what direction should I take? One option is to build
with the 9" motor, but still use the 84 V controller with bypass and 14 x 6 V
batteries and inexpensive charger. Later upgrade if "used parts" become
available.
But, if the first option can give me decent acceleration, it may work just
fine for meeting my original needs. So, my question is: Does anyone have any
experience using the EV-1 with bypass at 84 V with a 7" x 15", 36 V lift motor?
It may work just fine. But, if I build it, I'd sure like to be sure it will
work.
Suggestions?
Thanks,
Steve
--- End Message ---
