EV Digest 3982
Topics covered in this issue include:
1) Re: Motors in series? Torque vs. power?
by Lonnie Borntreger <[EMAIL PROTECTED]>
2) Re: Ideal motor RPM?
by Seth Allen <[EMAIL PROTECTED]>
3) Re: EVLN(Jr Not Changing tho talks clean)
by "Charles Whalen" <[EMAIL PROTECTED]>
4) NEDRA Wicked Watts February 4-6, 2005!
by "Chip Gribben" <[EMAIL PROTECTED]>
5) Re: EVLN(Jr Not Changing tho talks clean)
by "Bob Rice" <[EMAIL PROTECTED]>
6) Re: Ideal motor RPM?
by "Roland Wiench" <[EMAIL PROTECTED]>
7) Re: Motors in series? Torque vs. power?
by Lee Hart <[EMAIL PROTECTED]>
8) Re: More EV ideas
by Lee Hart <[EMAIL PROTECTED]>
9) UPS Re-use for EV
by [EMAIL PROTECTED]
10) Re: Ideal motor RPM?
by Lee Hart <[EMAIL PROTECTED]>
11) RE: Hybrid options for a pickup
by [EMAIL PROTECTED]
12) RE: Motors in series? Torque vs. power?
by "Mark Fowler" <[EMAIL PROTECTED]>
13) RE: Hybrid options for a pickup
by "David Roden (Akron OH USA)" <[EMAIL PROTECTED]>
14) Zivan NGx
by "Paul Compton" <[EMAIL PROTECTED]>
15) Sparrow article in the Akron Beacon Journal
by Rod Hower <[EMAIL PROTECTED]>
16) Re: Ideal motor RPM?
by Electro Automotive <[EMAIL PROTECTED]>
17) Re: Ideal motor RPM?
by "Ryan Stotts" <[EMAIL PROTECTED]>
18) RE: Motors in series? Torque vs. power?
by "Jamie Marshall \(GAMES\)" <[EMAIL PROTECTED]>
19) RE: Trying to avoid battricide...SOC stuff
by "Jamie Marshall \(GAMES\)" <[EMAIL PROTECTED]>
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On Tue, 2004-12-28 at 04:34 -0500, [EMAIL PROTECTED] wrote:
> Read some good responses from some knowledgeable-sounding folks. Let me
> respond to this answer to my question at the top:
>
> >1) if you are getting "twice the torque"
> >then what are you giving up (power perhaps)?
>
> >1) The power is the same either way. You get twice the torque at 1/2
> >the RPM (roughly speaking, in an ideal series wound motor you would
> >get 4 times the torque at 1/4 the RPM
>
> Okay, that was my suspicion, basically. "There is no free lunch" so to
> speak, so the power is the same.
>
> But if the power is the same, then what's the difference? I have two
> identical cars, except that one has two motors in series, and the other only
> has one
> motor. I have two identical drivers, and they are both on the drag strip. I
> say "go!" and they both floor the accelerator at the exact same time. At
> this
> point, one car is making "twice the torque at half the RMP" and one car is
> making "single the torque at full RMP" but both are making the exact same
> power.
> Is there a difference? Which car wins?
Ummm. Not quite right. I believe, at the risk of putting words in
someone's mouth, that the comment meant that a single motor would double
torque at 1/2 rpm.
If motor a puts out 100ft-lbs of torque at 200 rpm, then:
1 - it would put out, from the comment above, 200ft-lbs at 100 rpm
(although I thought that the torque/rpm curve was logarithmic, not
linear).
2 - adding a second identical motor (also puts out 100ft-lbs at 200 rpm)
then at 200 rpm you will have 200ft-lbs of torque..... twice the HP.....
and at 100 rpm, you would have 400ft-lbs, again twice the HP.
Another view of it.... Remember that rpm is related to voltage. With
two motors in series, to reach a certain rpm the voltage to the "motor
chain" must be twice as much to get the same rpm (each drops 1/2 the
voltage applied). Example, your motor is rated at 200 rpm at 24V. Then
to have that motor see 24V when in series with another identical motor,
then the controller has to be providing 48V across both motors. The
motor characteristics also determine how much current drawn given a
certain rpm and voltage, thus the current at 24V and 200 rpm is the same
whether it is in series with another motor or not. So, you are applying
the same current, at twice the voltage to your drive system......
P=VI.... twice the power at a given rpm.
Lonnie Borntreger
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What I found when I measured was that transmissions get rather
inefficient at high input shaft speeds and low torques (like highway
speed cruising). This isn't a revelation, but I was surprised at the
amount of power they could suck up. Without cutting holes in the side
of the case to look, it SEEMS like there is a fixed bearing drag, and a
RPM dependent drag, which I would guess is the moving of the fluid. It
could be little aliens in the case holding onto the gears, it doesn't
matter where it comes from, in general, the most efficient operation
point for the transmission is with as slow an input shaft speed as
possible, which means the highest gear.
So IF your motor efficiency doesn't drop significantly when you slow it
down say 1/4 and add 1/3 more torque AND it won't overheat, then top
gear should help. Ditching any built in fan and swapping out an
external one for the motor should help with efficiency. And exhaust the
motor heat onto the transmission to reduce the viscosity of the fluid.
And slowing down helps all the way around.
Seth
On Dec 28, 2004, at 12:27 AM, Ryan Stotts wrote:
Driving down the highway for example, those 8" and 9" Advanced D.C.
motors,
what is their ideal/optimal rpm to be ran at for extended periods?
If the speed limit is 60 or 65 for example, the ideal rpm could be had
by
first getting it roughly close by swapping out the ring and pinion
gears in
the differential. Then it could be fine tuned by tire height
selection..
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What a joke this article is! How can anyone take this cr*p seriously? Bill
Ford's environmental pretentions were forever irreparably tarnished and
exposed as a sham when he premeditatively murdered the Th!nk, and no amount
of greenwashing with the Escape Hybrid can change that!
And planting flowers on the roof of a factory? Oh please, give us a break!
Another joke! That roof space would be so much better used for
environmental purposes by covering it with solar panels to produce some of
the energy required to run the factory. But what would you expect from
Newsweek anyway?
Charles
----- Original Message -----
From: "bruce parmenter" <[EMAIL PROTECTED]>
To: "evlist" <[email protected]>
Sent: Monday, December 27, 2004 10:17 PM
Subject: EVLN(Jr Not Changing tho talks clean)
EVLN(Jr Not Changing tho talks clean)
[The Internet Electric Vehicle List News. For Public EV
informational purposes. Contact publication for reprint rights.]
--- {EVangel}
NEWSWEEK: Bill Ford Jr. Ready to Revive His Clean Revolution at
Auto Company; Says His 'Passion for the Environment Hasn't
Waned,' But Events 'Overtook' Him When He Became CEO
Says He Won't Veer Off The Garden Path Again;
'If People Judge
This Is The Wrong Path to Be On,
Then I'm Not The Guy to Do The Job...
I'm Not Changing'
NEW YORK, Dec. 5 /PRNewswire/ -- Ford Motor Co. CEO Bill Ford Jr.
tells Newsweek that he's ready to restart his clean revolution
now that his company is no longer losing money. "My passion for
the environment hasn't waned one bit over the years," he tells
Detroit Bureau Chief Keith Naughton in the current issue. "It's
just that events overtook me when I became CEO, and the fires
were raging everywhere."
Now Ford won't publicly commit to any hard targets, even refusing
to confirm leaks from his own execs that Ford is aiming to cut in
half the global-warming gases coming from its cars by 2030, which
will require an 80 percent boost in gas mileage. "These are the
kind of issues I'm driving personally," he says. "But I won't
speak externally to numbers because a cynic would say, 'Well,
it's easy to make a promise that far in the future'." He's right,
Naughton reports, but even his allies want something tangible on
how he's cleaning up his cars in the next five years-not in a
quarter-century. "We're rooting for him," says environmental
shareholder activist Mindy Lubber. "But he's got to act sooner."
Ford's long-awaited gas-electric-hybrid Escape SUV is finally on
the road and he's cranked up his new ecofriendly factory, with
the world's largest "living roof" blanketed in flowering ground
cover. He's even convened a panel of young execs to tackle the
thorny issue of how Ford can clean up its cars to combat global
warming. The boyish optimism he once displayed about saving the
planet has now been replaced by a world-weary determination to
re-establish Ford's green credibility-and his own, Naughton
reports in the December 13 issue of Newsweek (on newsstands
Monday, December 6).
Ford's next hybrid, a Mercury version of the Escape, won't arrive
until 2006, while Toyota will launch as many as four new hybrids
next year. Bill Ford clearly doesn't like playing catch-up. "I
can't control what people think of Toyota," he says. "All I can
control is what they think of us. And that's what I'm working
really hard to get right." He knows it will take more than one
hybrid and one clean factory. And he insists he won't veer off
the garden path again. "Ultimately, if people judge this is the
wrong road to be on, then I'm not the guy to do the job," he
says. "Because I'm not changing."
(Article attached. Read Newsweek's news releases at
http://www.Newsweek.com.
http://www.msnbc.msn.com/id/6652237/site/newsweek/
SOURCE Newsweek CO: Newsweek ST: New York SU:
Web site: http://www.newsweek.msnbc.com
http://www.prnewswire.com 12/05/2004 11:57 EST
=====
Bruce {EVangel} Parmenter
' ____
~/__|o\__
'@----- @'---(=
. http://geocities.com/brucedp/
. EV List Editor, RE & AFV newswires
. (originator of the above ASCII art)
=====
__________________________________________________
Do You Yahoo!?
Tired of spam? Yahoo! Mail has the best spam protection around
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--- End Message ---
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NEDRA will kick off the 2005 season with Wicked Watts February 4-6, with our
main event on Saturday, February 5. So get your EVs ready for 3 days of
fun-filled racing at the Las Vegas Speedway.
Brigham Young University will be there with their ultra-capacitor powered EV-1,
Brian Hall from Thunderstruck Motors plans to race and many more plan to come
out for this exciting event.
Richard Furniss and the Las Vegas Chapter of the EAA will be organizing the
event.
DATES AND TIMES
Friday, February 4 - Gates open at 8:00 am. The track will be closed in the
evening
Saturday, February 5 - Main Event. Gates open 8:00 am for a full day of racing.
Sunday, February 6 - Gates open at 8:00 am. For those who can't get enough.
For more information contact Richard Furniss at [EMAIL PROTECTED], the Las
Vegas EVA website at http://www.lveva.org and the NEDRA website at
http://www.nedra.com
We are looking for sponsors for this race and other races for the 2005 season.
Dates for the rest of the 2005 schedule including Power of DC and Woodburn are
in the planning stages and will be available soon. We are looking at a possible
date in July for Woodburn and a date in June for Power of DC.
Chip Gribben
NEDRA Webmaster
http://www.nedra.com
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--- Begin Message ---
----- Original Message -----
From: "Charles Whalen" <[EMAIL PROTECTED]>
To: "evlist" <[email protected]>
Sent: Tuesday, December 28, 2004 8:57 AM
Subject: Re: EVLN(Jr Not Changing tho talks clean)
> What a joke this article is! How can anyone take this cr*p seriously?
Bill
> Ford's environmental pretentions were forever irreparably tarnished and
> exposed as a sham when he premeditatively murdered the Th!nk, and no
amount
> of greenwashing with the Escape Hybrid can change that!
> Right on, Charlie!
If Bill Fraud, iI mean Ford wanted to DO something cool and good, bring
back the Think and start doing a EV in Dearborn, from the ground up, say a
Ford 500 size Li On powered family size vehicle. Instead of the silly
Escape/ I looked at that, cabin isn't a hellova lot bigger than my Prius,
but outside it is a SBT =Slow Boxy Thing, like all the OTHERS out there.
Drag co efficient of a Freight Diseasel locomotive and damn near as heavy! I
weighted up my Prius at my friendly Junkyard, only 2500 lbs or so, 200 lbs
lighter than my Sentra, a bit of a surprise. Whythehell won't/can't car
builders TELL you the curb weight of each vehicle, with gas and vital fluids
aboard, ain't going anywhere without them! Sure would make it easier to shop
for doners.Weighted the Rabbit 3100 with T 105's, goes close to 3300 with
the T 145's Gees! A load to pack, for sure! Car is detererating, but doesn't
seem to care about the weight, the rocker panels on the driver side are
rotting away. Normal thing with Rabbits and every OTHER kinda car in the
Least Coast theater of operation. But with bare metal underneith, like my
Sentra. Crawled under that, sandblasted the rust away, slopped rustoliun and
undercoating to slow the rot down a bit. Fighting the Rust-O-Matic cars all
come with from the factory.
> And planting flowers on the roof of a factory? Oh please, give us a
break!
> Another joke! That roof space would be so much better used for
> environmental purposes by covering it with solar panels to produce some of
> the energy required to run the factory. But what would you expect from
> Newsweek anyway?
> The flowers LOOK nice, but whatdoyaexpect from a CAR outfit. Look at the
impractical stuff with their cars. The White Star Line thought two rows of
Lifeboats on the Titanic would make the boat deck look too cluttered! And
on through history.
Oh yeah! One last thought on topic, a bit. Couldn't Ford write off the
EV Pogram, I mean PROGRAM as a tax loss? They have a lot of sharp tax guyz
in their employ, that could figure this one out. Sell EV's and get a tax
credit on each one? Would work til they hadta shut down the SBT factories to
switch over to EV production, by popular demand!
Seeya
Bob
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Used the following formula to calculated the motor RPM for a given speed:
WC = Wheel Circumference in inches.
(put a mark on the tire and grade and roll
the car one wheel turn and mark the grade
again. Measure between the two marks.
Ratio = Axil ratio or could be overall ratio
Constant = 1056 ( is deride from 5280 feet=1 mile
divided by 60 minutes times 12
inches)
Mph = (RPM x WC)/(Ratio x 1056) or
RPM = (MPH x Ratio x 1056)/WC
Ratio = (RPM x WC)/(MPH x 1056)
The Axil Ratio is indirectly proportion to the weight and speed. For
example by expermentation that it takes about 2400 watts to push 100 lbs of
weight to 50 mph for 60 minutes using a one to one overall ratio.
Therefore:
Watts = Weight = MPH = Time = Ratio
2400 100 50 60 1:1
24000 1000 50 60 1:1
48000 2000 50 60 1:1
12000 2000 50 60 4:1
18000 3000 50 60 4:1
24000 4000 50 60 4:1
9600 2000 50 60 5:1
14400 3000 50 60 5:1
19200 4000 50 60 5:1
8000 2000 50 60 6:1
12000 3000 50 60 6:1
16000 4000 50 60 6:1
24000 6000 50 60 6:1
My EV weighs 6000 lbs with 90 each 244 AH cells at 180 volts = 43920 or
44000 watts.
With a 5.57:1 axil ratio the amount of watts required is:
(24000 x 5.57)/6 = 22280 watts for 50mph for 1hr.
The RPM will be:
RPM = (50mph x 5.57 x 1056)/90 inch wheel cir.)
= about 3300 RPM.
The HorsePower Required:
(22280 watts/746) = 30.5
My motor hp is 32 HP.
Roland
----- Original Message -----
From: "Ryan Stotts" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Monday, December 27, 2004 10:27 PM
Subject: Ideal motor RPM?
> Driving down the highway for example, those 8" and 9" Advanced D.C.
> motors,
> what is their ideal/optimal rpm to be ran at for extended periods?
>
> If the speed limit is 60 or 65 for example, the ideal rpm could be had by
> first getting it roughly close by swapping out the ring and pinion gears
> in
> the differential. Then it could be fine tuned by tire height selection..
>
>
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>> I've noticed my 4 pole, series, ADC motor has the field poles in
>> series and the armature poles in parallel... can we pull the same
>> series/parallel trick on the armature of a single motor, similar
>> to what is being discussed for a two motor drive?
Joe Smalley wrote:
> There are four brushes alternating positive and negative around the
> commutator. All four quadrants of the armature are in parallel.
> The best I can imagine would be to change the polarity of two field
> poles to make it a two pole motor and then use only one pair of
> opposing brushes.
I don't think that would work very well. There are in effect 4 armature
coils. They are wired in a square, with a brush at each corner. Going
around the square, the brushes are + - + -. When powered, this structure
generates 2 north and 2 south poles. Thus, the field has to provide a
matching 2 north and 2 south poles.
Off the top of my head, I think if you connected power to only the
diagonal two + brushes (making one + and the other -), you'd have 4
times the armature resistance. The poles on its surface would be N N S
S. If you rewire the 4 field coils to produce the same poles (N N S S),
it should run as a 2-pole motor, but with a badly designed pole shape
(there would be a "hole" in the center of each N-N and S-S pole where
the peak field strength should be), and with twice the normal winding
resistance. So it would be a rather inefficient motor.
But, you *could* wire the 4 field poles in parallel, series, or
half-parallel, half series. The stock setup (all in series) provides the
lowest speed per volt and highest torque per amp. Half-series and
half-parallel is equivalent to 50% field weakening, and is faster per
volt, and less torque per amp. All fields in parallel would be
equivalent to 25% field weakening, even faster per volt and less torque
per amp.
It's usually easier to accomplish this with an external field weakening
resistor (far fewer connections).
But, there is a special case that is interesting. If you have two
motors, you can wire their armatures in series/parallel; and
independently wire their fields in series/parallel. Now your
combinations are:
armatures fields result (compared to a single motor)
--------- ------ -----------------------------------
parallel parallel stock rpm/volt, 2x torque/amp
(100% field)
parallel series less rpm/volt, 4x torque/amp
(200% field)
series series half rpm/volt, stock torque/amp
(100% field weakening)
series parallel more rpm/volt, half the torque/amp
(50% field weakening)
The parallel armatures, series fields case is interesting, because it
provides even more torque per amp. It could be useful for drag racing or
any time you need even more torque at low speed.
--
"Never doubt that the work of a small group of thoughtful, committed
citizens can change the world. Indeed, it's the only thing that ever
has!" -- Margaret Mead
--
Lee A. Hart 814 8th Ave N Sartell MN 56377 leeahart_at_earthlink.net
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[EMAIL PROTECTED] wrote:
> What about... an "acceleration pack" or "hybrid pack" -- having some
> batteries which are used for acceleration (maybe AGMs), and others
> for cruising (floodeds)... Anyway, have no idea if that's been
> proposed before, or if it's been done already, but add one more
> crappy idea from an EV idiot to the rest.
No, it's not a bad idea at all! It's been proposed before, and even
tried on occasion. I just don't think we've seen any experimental
results to say how well it works, and what surprises it holds.
The key challenge is that now you have two packs. This means two
chargers, two monitors (E-meters or equivalent), and two controllers (or
other means to decide which pack supplies power). This gets expensive.
So, it is human nature to look for a cheaper way: To try to "get by"
with only one charger, monitor, and/or controller. Maybe this works,
under ideal circumstances. But more likely, the two packs will not
cooperate. You may wind up damaging one pack or the other from excessive
charging or discharging, or not be able to control which pack supplies
your motor power. A good idea, badly implemented, becomes a bad idea.
As a first try, I'd probably have two packs of the same voltage, one
floodeds and one AGMs. Use a pair of isolating diodes to connect each
pack to a single controller's input (with a suitable main disconnect and
precharge circuit). This way, the higher voltage of the two pack will
supply your motor current.
I'd use two E-meters, one per pack, so you can see what each is doing.
This way you can tell if the "right" pack is supplying your power, and
during charging, you can tell that each pack is reaching "full".
Then I'd have either two chargers, or one charger that can be set to a
suitable charging algorithm for floodeds or AGMs. You could experiment
to see if you can charge the two packs in parallel for at least part of
the charge cycle (probably the bulk phase). But they will certainly need
different end-of-charge criteria.
--
"Never doubt that the work of a small group of thoughtful, committed
citizens can change the world. Indeed, it's the only thing that ever
has!" -- Margaret Mead
--
Lee A. Hart 814 8th Ave N Sartell MN 56377 leeahart_at_earthlink.net
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Our electrical department has several 1.15kVA UPS's that that are headed for
the dumpster. They each went into a failure mode, but they don't have the time
to troubleshoot. Chances are at least one of them can be fixed.
The units take 12VDC input, but you can parallel the batteries to increase the
capacity. The batteries are not part of the deal.
Could these have any use in an EV application?
I'm thinking not, only because at 1.15kVA, that means a maximum of 9.6 amps
output, but I thought I'd pose the question anyway.
Richard
http://www.austinev.org/evalbum/474.html
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Ryan Stotts wrote:
> Driving down the highway for example, those 8" and 9" Advanced D.C.
> motors, what is their ideal/optimal rpm to be ran at for extended
> periods?
It depends. The most efficient rpm for the motor is a function of the
torque it is being asked to deliver. The peak is also very broad; so
broad that other factors in the car will determine the most efficient
speed (wind resistance, transmission/differential losses, etc.).
Also, the ADC motors have an internal fan. Lower rpm is more efficient
in part because the internal fan is providing less cooling. But you
can't run this way for very long or it will overheat. Often, you need to
run it at higher rpm just to provide cooling.
--
"Never doubt that the work of a small group of thoughtful, committed
citizens can change the world. Indeed, it's the only thing that ever
has!" -- Margaret Mead
--
Lee A. Hart 814 8th Ave N Sartell MN 56377 leeahart_at_earthlink.net
--- End Message ---
--- Begin Message ---
Responses below.....
-----Original Message-----
From: Lee Hart [mailto:[EMAIL PROTECTED]
Sent: Tuesday, December 28, 2004 8:07 AM
To: [email protected]
Subject: Re: Hybrid options for a pickup
[EMAIL PROTECTED] wrote:
> I just read the post where someone suggested using a 4x4 front axle
> and attaching a motor to it to run just the front axle.
Yes; this is a viable strategy for building a simple hybrid.
Attaching an electric motor to the front differential might be hard;
it's pretty crowded up there in most cars. It might be easier to remove
the drive shaft to the rear axle, and use the electric motor to drive
it.
Well, now I wish I had bought a 4x4 instead of a 4x2. I bought this pickup
with the intent on converting it so it's a manual 4x2. This was before I got
my hands on the Rabbit. I'm going to post this question to a Nissan 4x4
forum but I'll also ask you guys just in case we have a Nissan truck expert
in the crowd. Is it a fairly straightforward affair to swap the front 4x2
axle in my 98 4 cyl Nissan Frontier with a 4x4 axle from a junk yard 4x4
front axle? Does it matter from what year truck I get it from? Can I get it
from a Nissan Hardbody?
> What would be the minimum motor size and voltage to be able to get
> say a 45 mph top speed and 20 mile range?
Electric motors don't work like ICEs -- they don't have a peak HP
rating. The more electrical power you feed in, the more mechanical
horsepower you get out NO MATTER HOW LARGE! What basically limits an
electric motor's size is heat. It works sort of like this:
- a 10 lbs motor can make 100 horsepower for 1 second
- a 20-lbs motor can make 100 HP for 10 seconds
- a 50 lbs motor can do it for 1 minute
- a 100 lbs motor for 10 minutes
- a 200 lbs motor for an hour
- a 400 lbs motor can do it continuously
So, with electric motors, you have to decide how much power you need,
and for how long you need it. In most EVs, you don't have enough battery
power to run at high power for more than a few minutes; thus, the motor
can be considerably smaller than you'd think.
In some hybrids (called serial hybrids), the ICE drives a generator
which in turn drives an electric motor to drive the wheels. If you build
a hybrid like this, then the ICE can deliver high power for a long time,
so you need a much larger electric motor and generator to handle the
power continuously.
In other hybrids (called parallel hybrids), the electric motor only runs
for very short times, or runs at very low power levels. For example, it
might be used only for accellerating or passing, or creeping around at
low speeds. In this case, the electric motor and generator can be much
smaller.
This will definitely be a parallel hybrid. I think a series hybrid would be
too complex for my skill level. Plus I want the stealth mode ;-)
> I assume an E-Tek is too small and would be toast in short order.
It mould work for a parallel hybrid, but not a series hybrid. Still,
it's a pretty lightly-built motor. There are better choices.
Yeah, looking at it again I think the 96v rated 6.7" might be my best bet as
far as power and cost goes.
> How would you control it?
Control strategies are the bane of hybrid designs. There are ENDLESS
ideas for the best way to do it. Everything depends on what you are
trying to get it to do.
I suppose the simplest strategy would be to have two accellerators; one
for the ICE and one for electric. You could choose which one (or both)
you wanted to use. Once you have figured out when and how you use each
one, maybe then look for schemes to combine them so the car
automatically uses the "right" one.
I think I'm leaning towards a motorcycle style throttle on the shifter. Two
pedals might be dangerous for an absent-minded person like me ;-)
> How tough would it be to charge the pack from the alternator while
> in ICE mode?
Not hard at all. Basically, you would have a battery pack of some size
(how big depends on how far and how fast you want it to go on pure
electric). Then put an alternator or generator on the ICE set up to
charge this pack.
> Do DC to DC conveters go in the other direction, 12v to 72v or 96v?
Yes; you can get DC/DC converters for any input and output voltage.
However, a given converter only works one way -- 12v to 72v, but not 72v
to 12. Thus, if you want power to go both ways, you need two DC/DCs.
I didn't want power to go both ways, I was just thinking I could use a 12v
to 72v (or whatever the pack voltage will be) tapped off of the 12v system
instead if sending 12v power to a 120vac inverter to run an onboard charger.
Do you think I would need a dedicated alternator? Or just a single high
output alternator? Keep in mind that while it's still a straight ICE vehicle
I'm going to install both an electric water pump and an electric cooling fan
to take loads off of the engine to make it run more efficiently. The pump
and fan both have electronic monitoring systems that will run them only when
needed.
> What happens to a DC motor when it freewheels? Can anything be
> damaged?
It acts as a generator. You can either ignore the power it generates, in
which case it just freewheels and consumes essentially no power. Or, you
can use the power it generates to charge the batteries (regenerative
braking) or just burn it up in resistors (dynamic braking).
> I'd like to make my pick up (98 Nissan Frontier) as fuel efficient
> as possible by possibly making it a hybrid. I would like to be able
> to make it run under battery power, with the engine at idle so I'll
> have steering and brakes, when accelerating from a stop or backing
> up.
That's a good simple plan. It won't give you the ultimate in gas
mileage, but is simple to implement.
> One, put hub motor wheels on the front
Hub motors are essentially "unobtainium". In other words, you can't get
them.
> and batteries under the bed.
That's fine. For a hybrid, you don't need all that big a battery pack,
since EV-only range can be quite short.
> Is it possible to machine a cover that would replace the cover
> on the back of the rear differential that would have a motor
Yes, it's possible. It adds a lot of weight to the rear axle though. It
may be better to cut the drive shaft, and use a motor with a shaft at
both ends. Couple the ends of the drive shaft to each end of the motor
with universal joints, so the motor mounts to the frame.
Wow, that's an awesome idea. That never would have occured to me to try.
> A small 72v system might be a good option for this arrangement.
> Six Exide Orbitals under the bed, a DCP 600 or Curtis, and a 72v
> charger. Or it could be charged off of the engine with a high
> output alternator. Or both.
Right. Or, you could use a shunt motor (such as an aircraft surplus
starter-generator) and just let the driveshaft spin it as a generator to
recharge the batteries.
And I might be able to find on that goes a lot cheaper than an ADC would.
> The motor would just be used for slow speeds and would freewheel
> when not in use.
A classic series hybrid.
> The main drawback I see with this is I'm not sure I could sufficiently
> protect the motor from the elements.
Not really hard. Put it in a sheetmetal sleeve. Use an external blower
to blow air thru it.
Any recommendations on 12v blowers for an ADC motor?
> Somehow mount the motor to the engine and set it up to drive
> the engine with a belt, like an alternator or AC pump in reverse.
Possible, but harder. Many engine compartments don't have the room. You
would need a pretty stout belt or chain if it was to handle significant
power.
Another problem with this arrangement is that the electric motor and ICE
are locked together. You can't let the ICE idle and run the electric
motor at high speed or high power.
> Don't know if this is possible with all the drivetrain movement but
> how about mounting a motor between the framerails forward of the
> rear diff and driving the driveshaft with a gear of some sort welded
> to the shaft or teeth that are machined into the shaft itself.
I don't think it would work for gears, but you could probably have
pulleys on the drive shaft, and a pair of belts and motors (one left,
one right) so it equalizes the side thrust. It would probably take
multiple V-belts to handle the torque and the slight misalignment as the
drive shaft moves up/down with suspension movement.
Thanks for the ideas!!!
John
--
"Never doubt that the work of a small group of thoughtful, committed
citizens can change the world. Indeed, it's the only thing that ever
has!" -- Margaret Mead
--
Lee A. Hart 814 8th Ave N Sartell MN 56377 leeahart_at_earthlink.net
--- End Message ---
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A very black-and-white simplification...
At the start of a drag race you want torque - lots of it - for a
massively quick launch.
At the end of a drag race you want RPM for top end speed.
Somewhere in the middle you want to change from series to parallel to
get the quickest overall time.
Doing the series/parallel thing with electric motors is a lot like a
mechanical gearbox.
Series is low gear. Lots of torque, low RPM, same overall power.
Parallel is high gear. Low torque, high RPM, same overall power.
In a race between a series motored car and a parallel motored car, the
series car would take off the quickest, but the parallel car would
gradually catch up with its higher top speed.
Would they cross the line at the exact same time?
I doubt it - there are so many factors to take into consideration.
Which one would win?
Dunno - for the same reasons.
The best compromise is to switch between series and parallel, just like
changing gears.
Otmar's Zilla controllers can handle this automatically based on the
current flowing through the system.
(Oops - just reread your post - you were asking about single motor vs.
two in series)
Well a single motor will have less torque than two motors in series and
less speed than two motors in parallel.
This assumes that the batteries and controller are capable of dishing
out more power than a single motor can handle.
I guess that's what it comes down to. A motor is a device for converting
electrical power to mechanical power. Under some circumstances it does
this job very efficiently, under others it wastes a lot of that input
power.
A dual motor setup allows you to run the motors more efficiently at both
low and high RPM compared to a single motor setup. (Just like a
gearbox.)
Mark
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Sent: Tuesday, 28 December 2004 8:34 PM
To: [email protected]
Subject: Re: Motors in series? Torque vs. power?
...
But if the power is the same, then what's the difference? I have two
identical cars, except that one has two motors in series, and the other
only has one
motor. I have two identical drivers, and they are both on the drag
strip. I
say "go!" and they both floor the accelerator at the exact same time.
At this
point, one car is making "twice the torque at half the RMP" and one car
is
making "single the torque at full RMP" but both are making the exact
same power.
Is there a difference? Which car wins?
...
If you tell me there is no difference in power or pulling ability
between the
cars, and both will cross the finish line the exact same time, then I
will
ask "then why bother setting up two motors in series in the first
place?"
...
Thanks.
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Some other vehicles have been made into the kind of parallel hybrid you're
considering. Audi prototyped a Quattro with a gas engine in front and motor
in back. I seem to recall a Volvo with a similar layout. I also recall a
homebrewed Subaru which was more like the auto companies' "hybrids" (it
used the motor to boost acceleration, not to actually move the car), and GM
and Chrysler have both proposed "through the road mild hybrids."
The advantages of using a p'up chassis for this project is that there's lots of
room to shoehorn in all the extra components (you essentially have two
complete drive systems to find homes for), and ample capacity for extra
mass of batteries and components. The disadvantages of a p'up are higher
weight and so-so aerodynamic qualities compared to a car.
One interesting strategy might be to use the p'up as a test bed to experiment
with various layouts and control schemes. Then, when you have the design
somewhat stable, try to transfer it to something lighter and more efficient.
You might consider a Honda Civic - perhaps the rear axle from one of the
early-90s 4wd wagons could be adapted to a more recent hatchback or
sedan.
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I've reverse engineered the logic board from a Zivan NGx series charger and
put a PDF file up on the web. Some of the component values may be specific
to 156v (ex Sparrow charger).
http://www.compton.vispa.com/Old_NG3_logic.pdf
Please let me know if you find any errors
Paul Compton
www.sciroccoev.co.uk
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http://www.ohio.com/mld/ohio/2004/12/26/business/10496545.htm
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At 11:27 PM 12/27/04 -0600, you wrote:
Driving down the highway for example, those 8" and 9" Advanced D.C. motors,
what is their ideal/optimal rpm to be ran at for extended periods?
If the speed limit is 60 or 65 for example, the ideal rpm could be had by
first getting it roughly close by swapping out the ring and pinion gears in
the differential. Then it could be fine tuned by tire height selection..
"Extended periods"? At 60 mph, you've got maybe an hour. You're not going
to cruise all day on the highway like you do in a gas car. Are you really
going to spend your entire range at one speed?
Shari Prange
Electro Automotive POB 1113 Felton CA 95018-1113 Telephone 831-429-1989
http://www.electroauto.com [EMAIL PROTECTED]
Electric Car Conversion Kits * Components * Books * Videos * Since 1979
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----- Original Message -----
>"Extended periods"? At 60 mph, you've got maybe an hour. You're not going
>to cruise all day on the highway like you do in a gas car. Are you really
>going to spend your entire range at one speed?
In some states, interstate traffic is light and a steady speed on the
highway can be
maintained. I feel with a possible gear change in the differential and tire
height
selection, an ideal motor rpm could be had at a selected mph. With a manual
5-speed transmission, getting around town would be no problem in regards to
having the selected highway speed dialed in like that.
What is your desired highway cruising mph? What rpm do you want to run the
motor at on the highway? Pick the number and it can be had.
"In 5th gear, at this mph, I want this ___ rpm."
Check this out:
http://www.corral.net/tech/gearcalc.html
Additional example info for the caculator link posted above:
You know that little Borg-Warner T5 transmission? It's in a lot of
different cars
and trucks. Looks just like this:
http://ddperformance.com/images/t5a.jpg
The transmission gear ratios are here:
http://ddperformance.com/Trans%20ID%20chart.htm
1st gear: 2.95
2nd gear: 1.94
3rd gear: 1.34
4th gear: 1.00
5th gear : .63
FYI: Most older 3 and 4 speed manual transmissions top gear is 1:1. Hence
no "overdrive".
Common rear end gear ratio's for '87-93 Mustangs were 2.73, or 3.08
(Considered "highway gears"). "Performance" gears are 3.27, 3.55, 3.73,
4.10, etc.
All in the 8.8" Ford rear end.
Summary:
Using that calculator, input your current tire size and the mph of your
choice(60 or 65 for example),
look at that page with the transmission gear ratios and see if you can find
one that matches your
current transmissions top gear. Enter in your current gear ratio that is in
your differential and now
you can get the motor rpm. Buy adjusting the tire height and maybe even a
rear end gear swap,
you can have any rpm you want at a chosen speed.
This site has nice tables showing tire height in inches. How is one to know
that a 215/65/R15 tire
is 26" tall for example? And if you changed to a 195/60/R15 at 24", the
effect on your motors rpm...
http://www.pepboys.com/
Basically, would you want a higher or lower rpm when you are on the highway?
Or if you only do
around town driving, having low gears in the differential sure would make it
easy on the motor..
Regards
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The difference between one motor and two in series is that the two in
series are both resisting the flow of the current, and therefore
doubling the voltage on the motor side of the controller.
In a perfect world you would be using twice the watts (same amps, double
volts). The higher resistance should cause smaller amps, but amps is
usually limited by factors other than the motor. (controller rating,
wiring, etc).
So if I have a controller that is rated for 1K amps, and I dump all of
it to a single motor at launch, the motor amps is maybe limited to 50v.
But my pack is 120v, so the controller is holding back, so as not to
blow itself up.
Now if I add another motor in series, I can dump the same 1k amps, but
I'm feeding both motors with that current. The total voltage on the
motor side of the controller is not 100v, so I'm using twice the
electricity, and getting twice the power.
-Jamie
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of [EMAIL PROTECTED]
Sent: Tuesday, December 28, 2004 1:34 AM
To: [email protected]
Subject: Re: Motors in series? Torque vs. power?
Read some good responses from some knowledgeable-sounding folks. Let me
respond to this answer to my question at the top:
>1) if you are getting "twice the torque"
>then what are you giving up (power perhaps)?
>1) The power is the same either way. You get twice the torque at 1/2
>the RPM (roughly speaking, in an ideal series wound motor you would
>get 4 times the torque at 1/4 the RPM
Okay, that was my suspicion, basically. "There is no free lunch" so to
speak, so the power is the same.
But if the power is the same, then what's the difference? I have two
identical cars, except that one has two motors in series, and the other
only has one
motor. I have two identical drivers, and they are both on the drag
strip. I
say "go!" and they both floor the accelerator at the exact same time.
At this
point, one car is making "twice the torque at half the RMP" and one car
is
making "single the torque at full RMP" but both are making the exact
same power.
Is there a difference? Which car wins?
If you say that one car (the two motors in series car) "pulls harder,"
then
doesn't that translate into more power at the wheels? Well, no, because
we
have just said that power is identical. Both cars have exactly the same
power.
So the question becomes, is all power created equal, or not? Is some
power
"better" or "more powerful" than other power? When I am measuring power
at the
rear wheels on both of these cars, is it possible to say "yeah, they are
both
the same power, but that car is still pulling harder than this one, and
will
win?"
If you tell me there is no difference in power or pulling ability
between the
cars, and both will cross the finish line the exact same time, then I
will
ask "then why bother setting up two motors in series in the first
place?"
If these are perceived as stupid questions, please forgive me. I'm not
trying to be difficult - I just want to learn. I actually have a fairly
good
college physics background and what not - that's why I'm asking the
questions. In
fact, a little bit of knowlege is a dangerous thing, they say. Perhaps
if I
had no physics knowledge at all I wouldn't be asking anything. But to
me,
power was always power, and was always "created equal" if you know what
I mean.
Thanks.
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So if this lower SOC is only apparent, how does it affect lifespan?
Will drawing 20 amphours 100 times from a cold battery kill it faster
than drawing 20 amphours 100 times from a warm one?
-Jamie
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Lee Hart
Sent: Saturday, December 25, 2004 9:30 PM
To: [email protected]
Subject: Re: Trying to avoid battricide...SOC stuff
Ryan Bohm wrote:
> I got back from a short drive, and let the batteries sit for a
> couple hours... But my measurements after letting them sit are
> worrying me. They are all in about the 11.8V range. According
> to what Lee recently said, that would be below 0% SOC for any
> of the batteries he mentioned.
It worries me that their voltage is this low. This indeed implies that
they are very dead. However, there are two mitigating circumstances.
First, they were cold; second, you only waited 2 hours after driving.
Cold batteries sag more and take longer to recover, and 2 hours is not
enough time for the voltage to stabilize. So if you can, wait more like
8-24 hours after driving and measure the voltage again.
> Does anyone have any rough numbers for how SOC changes with
> temperature?
Actual state of charge doesn't change with temperature, but the USABLE
amount of charge left does. For example, a battery can be at 50% SOC at
70 deg.C -- half its amphours are left. Chill it to 0 deg.F, and its
voltage hardly changes -- it is *still* technically at 50% SOC. However,
if you put it under a heavy load, its voltage falls almost immediately
below 1.75v/cell (dead). It is not dead, but its internal resistance is
so high that you can't get EV-levels of current from it any more. So, it
is effectively dead (0% SOC) at this temperature and current.
But, let it warm back up to 70 deg.F. Again, its voltage doesn't change
-- but now you have a much lower internal resistance, and have your
capacity back!
> I'd like to build that into my SOC measuring device... along with
> current measurement and raw, instantaneous voltage. Not sure how to
> do it after that - a table lookup seems to be the most reasonable,
> other than it will be a big table!
The relationship is complex, and difficult to program into any sort of
instrument. It is also hard because you don't *know* the relationship.
I think one of the better ways to do it is the "dual meter" approach.
Get an analog meter with two pointers that cross (the type used in SWR
meters for radio use). Wire one to measure battery current, and the
other for battery voltage. The place where the two pointers cross
defines the present battery operating point. At any given current, the
voltage changes from some value at 'full' to another value at 'empty'.
This defines a line across the dual meter's face.
The simplest way to label such a meter is with colored red-yellow-green
bands that show the combinations of values for full-empty and good-bad
battery. You can thus tell at a glance that this voltage represents 50%
SOC at the present current.
Of course, you can digitize the process as well; but it will be harder
to label the scales.
--
"Never doubt that the work of a small group of thoughtful, committed
citizens can change the world. Indeed, it's the only thing that ever
has!" -- Margaret Mead
--
Lee A. Hart 814 8th Ave N Sartell MN 56377 leeahart_at_earthlink.net
--- End Message ---
