EV Digest 6971
Topics covered in this issue include:
1) Throttle strategy and Current Limit
by Chet Fields <[EMAIL PROTECTED]>
2) Re: electric bicycle - need help
by "Kip C. Anderson" <[EMAIL PROTECTED]>
3) Re: electric bicycle - need help
by "Lawrence Rhodes" <[EMAIL PROTECTED]>
4) RE: Trojan costs
by "Nawaz Qureshi" <[EMAIL PROTECTED]>
5) Re: Motor weight
by Lee Hart <[EMAIL PROTECTED]>
6) Re: Trojan costs
by "Roland Wiench" <[EMAIL PROTECTED]>
7) RE: Hybrids done right, Re: Would you build if you could buy?
by Lee Hart <[EMAIL PROTECTED]>
8) Re: Hybrids done right, Re: Would you build if you could buy?
by "Evan Tuer" <[EMAIL PROTECTED]>
9) RE: electric bicycle - need help
by Mike Willmon <[EMAIL PROTECTED]>
10) Re: AC HP or kW
by "Brian Pikkula" <[EMAIL PROTECTED]>
11) .
by "John Nicholson" <[EMAIL PROTECTED]>
12) Re: Building A Motor
by "Andre' Blanchard" <[EMAIL PROTECTED]>
13) RE: Made the first step recently...
by "damon henry" <[EMAIL PROTECTED]>
14) The Story of Air Conditioning, tongue in cheek.OT a Tad
by "Bob Rice" <[EMAIL PROTECTED]>
15) Re: Adapter Problem
by "Tehben Dean" <[EMAIL PROTECTED]>
16) Re: Made the first step recently...
by "Mark Eidson" <[EMAIL PROTECTED]>
17) Re: Motor weight, No Escape!
by "Bob Rice" <[EMAIL PROTECTED]>
18) Re: electric bicycle - need help - air drag as a function of speed
by "Phil Marino" <[EMAIL PROTECTED]>
19) Re: NiMH pack strategy
by "Joseph T. " <[EMAIL PROTECTED]>
20) Re: Throttle strategy and Current Limit
by Eric Poulsen <[EMAIL PROTECTED]>
21) Re: Adapter Problem
by "Joseph T. " <[EMAIL PROTECTED]>
22) Re: Adapter Problem
by David Dymaxion <[EMAIL PROTECTED]>
23) Re: electric bicycle - need help
by "Peter VanDerWal" <[EMAIL PROTECTED]>
--- Begin Message ---
I am progressing quite well on my controller design and now have a couple of
specific questions
that you all might be able to help me with.
After reading recently about different throttle behavior I have rethought the
way I am doing it. I
was just letting the level of input from the pot translate into a percentage of
duty cycle (with
current limiting and low voltage just reducing it). However, now I thought
maybe I should approach
it from the angle of the input establishing a desired current level and then
have a circuit that
would compare that to the actual via an op-amp at maximum gain that would then
either charge or
discharge a capacitor through a resistor that would then be the actual signal
for the PWM
percentage. I thought of this as I was designing my regen circuit off of the
brake signal. But I
guess it would also work just as well for the accelerator side as well.
My first question is: Do opamps allow you to sink as well as source the
current? In other words,
when the opamp output is 0v will it drain the capacitor and allow the voltage
to drop?
And the second is this: Will this control be fast enough to limit current etc.
Or should I also
have at a later stage some mechanism that will actually shut off the output to
the gate drive
input when the current exceeds my maxlimits?
--- End Message ---
--- Begin Message ---
I can't help with the calculations, but I agree that a 750W motor probably
isn't going to get you there at it's rated voltage. I have however seen
video of a guy with a hub motored bike claiming 45 mph performance. Even
with a 1000W hub motor, it took a fair distance to get up past 40 and I
don't know what voltage he was running.
The nice thing about hub motors is that they come in varied windings that
would allow this kind of speed without worrying about overspeeding. There
are dual-wound motors for mixed low end and high speed performance as well.
Crystalyte seems to offer the best range of choices for that right now.
- Kip
----- Original Message -----
From: "James Drysdale" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Cc: "James Drysdale" <[EMAIL PROTECTED]>
Sent: Friday, June 29, 2007 1:45 AM
Subject: electric bicycle - need help
G'day all,
Not an electric automobile, but an electric vehicle nonetheless.
I'd like to create a hybrid muscle-electric bicycle.
But I need some help.
1) Trying to work out how much *power* a specific 750W will actually
give me.
Power = (force * displacement) / time
Force = mass * acceleration
I am stuck, insufficient info and/or knowledge.
2) To move my fully-laden bicycle up to a speed of 80km/h
(49.67miles/h), how powerful a motor will I need?
Information I do have......
mass = 120kg
desired velocity = 22.2 m/s (80km/h or 49.67 miles/h)
Where I am stuck is in the acceleration & force equations.
I do not know how much acceleration and max forward velocity I can
achieve with a 750W motor.
This is the motor in question!!!
https://www.electricscooterparts.com/ShoppingCart.asp?ProductCode=MOT-36750G
From this page.
http://www.electricscooterparts.com/motors.html
36volt
750watt
2500rpm geared down to 420rpm
I realise that there are other factors here that need addressing, like I
said, I need help.
Is it okay to disregard factors such as wind resistance for now?
Wind resistance increases as the square of the velocity or something
like that.....
Cheers all,
James Drysdale.
--- End Message ---
--- Begin Message ---
The Zappy list is a good place to get more info. Lots of people working
with smaller motors. Not to put down the evlist. Many of the same people
are here too. Lawrence Rhodes
----- Original Message -----
From: "James Drysdale" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Cc: "James Drysdale" <[EMAIL PROTECTED]>
Sent: Friday, June 29, 2007 1:45 AM
Subject: electric bicycle - need help
> G'day all,
>
> Not an electric automobile, but an electric vehicle nonetheless.
> I'd like to create a hybrid muscle-electric bicycle.
>
> But I need some help.
> 1) Trying to work out how much *power* a specific 750W will actually
> give me.
>
> Power = (force * displacement) / time
> Force = mass * acceleration
> I am stuck, insufficient info and/or knowledge.
>
> 2) To move my fully-laden bicycle up to a speed of 80km/h
> (49.67miles/h), how powerful a motor will I need?
>
> Information I do have......
> mass = 120kg
> desired velocity = 22.2 m/s (80km/h or 49.67 miles/h)
>
> Where I am stuck is in the acceleration & force equations.
> I do not know how much acceleration and max forward velocity I can
> achieve with a 750W motor.
>
> This is the motor in question!!!
>
https://www.electricscooterparts.com/ShoppingCart.asp?ProductCode=MOT-36750G
> >From this page.
> http://www.electricscooterparts.com/motors.html
> 36volt
> 750watt
> 2500rpm geared down to 420rpm
>
> I realise that there are other factors here that need addressing, like I
> said, I need help.
> Is it okay to disregard factors such as wind resistance for now?
> Wind resistance increases as the square of the velocity or something
> like that.....
>
>
> Cheers all,
> James Drysdale.
>
--- End Message ---
--- Begin Message ---
FWIW:
I was the head of Engineering at Trojan from 1982 to 1993. Trojan never had
any patents whatsoever on the batteries or components. In 1993 Trojan got a
patent on the Mastervent.
Nawaz Qureshi
Vice-President of Engineering
U.S. Battery Mfg. Co.
1675 Sampson Avenue
Corona, CA 92879-1889
[EMAIL PROTECTED]
T: 951-371-8090
Fax: 951-371-4671
Making the simple complicated is commonplace; making the complicated simple,
awesomely simple, that's creativity - Charles Mingus
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Sent: Friday, June 29, 2007 7:17 AM
To: ev@listproc.sjsu.edu
Subject: Trojan costs
comment if you know better.
I was in line at PepBoys talking to a fellow customer who discoverred I had
an EV thru conversation. He is a bulk battery purchaser for floor
polishers.
Of course he knew that the Trojan is the best battery out there if you
don't want to be replacing them so frequently.
So, I asked what happened to cause the Trojan battery price to skyrocket
(racketeering?) NO.
------------------------------------
He claims that because the Patent on the Trojan's has run out,
Trojan is "giving more to the sales man to keep Deka's out".
------------------------------------
I was quite confused by that comment, as I would think a open patent would
open the market for competition.
Does he mean that, The sales man is allowed to charge a higher margin
whereas it used to be restricted.
Defies logic?
We did get talking about the new battery he wants for his floor polishers:
LiFeSO4 Lithium Iron Sulfate, because they'll have higher power, great
recharge cycles, but it is critical to have a controller per battery,
otherwise if it gets wet, it'll dump all it's power instantly (OH JOY!)
at double the cost of the current Trojan battery, I'll hold off. but I'm
glad there's more battery chemistry development.
If the patent only recently expried, should we be seeing 220 AHr Deka's?
with 2,000 recharges? at competitive prices or other mfg's? anyone in the
battery market loop?
Thanks, Ben
--- End Message ---
--- Begin Message ---
From: Roland Wiench
> You can build a rotating machine, without a metal casing as in a
> motor. This is done by using just using a large amount of copper
> windings wound around a plastic or fiberglass core.
>
> ...a 30 hp motor-generation would take a coil form about 4 foot
> in diameter and 12 feet high...
No, it's not *that* bad, unless the motor designer is extremely ignorant! This
is what would happen if you just tried to replace all the iron in a
conventional motor with plastic.
But there really are ironless motors, and they work quite well for specialized
applications.
To understand the principles involved, first think about a transformer. As you
reduce the amount of iron, the size and weight of course go down. But the
inductance also goes down. The voltage per turn V = L di/dt, so if L goes down,
di/dt must go up. Basically, this means the operating frequency must go up. For
example,
- A 100 watt 60 Hz transformer (standard power transformer) is
about the size of your fist, and is 75% iron.
- A 100 watt 60 KHz transformer (as used in a switching power
supply) has 1% of the amount of iron, and is about the size
of a golf ball.
- A 100 watt 60 MHz transformer (as used in a radio transmitter)
has no iron at all, and is the size of a few pennies stacked up.
All of these transformers are in excess of 90% efficient if well made. As
frequency goes up, magnetic losses go up but copper losses go down, because
they use less copper (fewer turns of thicker wire).
Now for motors. The challenge with high frequency motors is that speed is
proportional to frequency. RPM = 120 x frequency / poles. It gets hard (i.e.
expensive) to go much faster than 10,000 rpm at any reasonable horsepower. We
have EV-size motors that can run as fast as 13,000 rpm, but they avoid actually
operating there for any length of time, due to bearing balancing and strength
of materials issues. So, a more practical way to raise the frequency is to
raise the number of poles.
- A common 1 hp 60 hz motor 2-pole motor runs at 3600 rpm, and
weighs about 25 lbs.
- A 1 hp 8-pole 400 hz aircraft motor runs at 6000 rpm, and
weighs about 10 lbs.
- A 1hp 24-pole 2 KHz stepper motor runs at 10,000 rpm, and
weighs around 5 lbs.
But high pole numbers create other difficulties; you won't find many examples
of motors with really high pole counts outside of the laboratory. Each pole is
essentially a little transformer, with its own primary and secondary and little
cores. A 100-pole motor would be built like 100 little motors oriented in a
circle -- an expensive style of construction.
In the days before vacuum tubes were invented, Nikola Tesla built some 100 KHz
motors 1000-pole motors just to see what could be done. They worked, but had no
practical applications. (Later, he realized he could have put a carbon
microphone in the field, and create an AM radio transmitter! But by then, the
vacuum tube had been invented, which did it much easier).
"The only thing new is the history you don't know yet." -- Harry Truman
--- End Message ---
--- Begin Message ---
Hello Ben,
Several months ago, I call the Trojan battery distributor of which I bought
a pallet load of 50 batteries from him back in 2002. I paid $73.00 each
with the old battery exchange at that time. Today I got a quote for $107.00
for 50 batteries. A pallet load of 50 is the minimum I can purchase from a
distributor, other wise I would have to go to a dealer which may be up to
$137.00 each.
This is $30.00 difference per battery or for 30 batteries, that is $900.00
savings. If I only using 40 batteries or 240 volts, than the extra 10
batteries cost me only $170.00 extra at dealers prices.
Use the extra batteries for a UPS system for your house, or put on a
maintainer and use as spares or replacements.
Roland
----- Original Message -----
From: <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Friday, June 29, 2007 8:16 AM
Subject: Trojan costs
> comment if you know better.
> I was in line at PepBoys talking to a fellow customer who discoverred I
> had
> an EV thru conversation. He is a bulk battery purchaser for floor
> polishers.
>
> Of course he knew that the Trojan is the best battery out there if you
> don't want to be replacing them so frequently.
>
> So, I asked what happened to cause the Trojan battery price to skyrocket
> (racketeering?) NO.
>
> ------------------------------------
> He claims that because the Patent on the Trojan's has run out,
> Trojan is "giving more to the sales man to keep Deka's out".
> ------------------------------------
> I was quite confused by that comment, as I would think a open patent would
> open the market for competition.
> Does he mean that, The sales man is allowed to charge a higher margin
> whereas it used to be restricted.
> Defies logic?
>
> We did get talking about the new battery he wants for his floor polishers:
> LiFeSO4 Lithium Iron Sulfate, because they'll have higher power, great
> recharge cycles, but it is critical to have a controller per battery,
> otherwise if it gets wet, it'll dump all it's power instantly (OH JOY!)
>
> at double the cost of the current Trojan battery, I'll hold off. but I'm
> glad there's more battery chemistry development.
>
> If the patent only recently expried, should we be seeing 220 AHr Deka's?
> with 2,000 recharges? at competitive prices or other mfg's? anyone in the
> battery market loop?
>
> Thanks, Ben
>
>
--- End Message ---
--- Begin Message ---
From: "Dewey, Jody R ATC COMNAVAIRLANT, N422G5G"
> And Honda quit making them right? I guess it was from lack of sales?
> The only one to get now is the Civic Hybrid.
I think there are a couple reasons why the Honda Insight was discontinued.
It was their first hybrid design, and now about 10 years old. That's about when
most cars are either discontinued (if that model didn't sell well enough) or
redesigned (if it did).
Second, it was a difficult, and thus expensive car to make. The aluminum body
and hybrid components were specialized, and not shared with any other cars in
their product line.
I think they decided to concentrate on the Civic Hybrid, because it sells a lot
better.
From: "damon henry"
>> With the recent threads of people wanting to build their own
>> hybrids I can't help but ask myself why? This is as I look out
>> at my 2001 Honda Insight that I bought brand new and still love.
The factory hybrids are great cars! I own one myself. But, they aren't EVs. And
they aren't built to allow an easy conversion to EV, or even to a plug-in
hybrid.
>> It leads me to the question of what you would do if you could buy
>> a factory EV...
Personally, I want a little around-town car for commuting and running errands
etc. that seats 4, and is cheap to operate. A high initial cost is OK as long
as it will save money in the long run.
And sure; I'd pay a premium if it had some "gotta have it" features that
happened to appeal to me. For everyone, these will be different. It might be
wild styling, or high performance, or a killer sound system, or a "chick
magnet", or a high "geek" factor. But these are hard to predict.
--
"Excellence does not require perfection." -- Henry James
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart-at-earthlink.net
--- End Message ---
--- Begin Message ---
On 6/29/07, Lee Hart <[EMAIL PROTECTED]> wrote:
And sure; I'd pay a premium if it had some "gotta have it" features that
happened to
appeal to me. For everyone, these will be different. It might be wild styling,
or high
performance, or a killer sound system, or a "chick magnet", or a high "geek"
factor. But
these are hard to predict.
Someone should invent a "chick electromagnet". Much more powerful
than the usual kind, and it would plug into your traction pack. Great
idea, I must patent it :)
--- End Message ---
--- Begin Message ---
Way back then they were monthly. It was the December Issue in 1983.
I hope you find it. I have the magazine in my house somewhere. AI can find
all the other ones that I didn't put in a "special"
place :-O
> James Drysdale wrote:
>
> Digital reproductions are only available from 1993 onwards.
> And they have no listing for December 1983, but as they appear to be
> published quarterly I assume you mean October - December of 1983?
>
--- End Message ---
--- Begin Message ---
Does anyone have a source for a 5HP 90 to 150 VDC motor? The closest
I could find in the rpm rang of 1000 to 300o is here:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ih=003&sspagename=STRK%3AMEWA%3AIT&viewitem=&item=130128546415&rd=1&rd=1
On 6/29/07, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
AC compressor is supposed to take 5 HP or 4 kW of power off the engine to
function. according to wikipedia.
At 156 volts, that's about 25 amps when loaded.
Wow, that's a chunk of power, though I don't know the on/off cycle time of
the compressor till I actually run it.
Ben
--
Brian in TX
http://www.austinev.org/evalbum/960
http://www.evdub.blogspot.com/
It may seem like I am doing nothing, but on a cellular level I'm
really quite busy.
--- End Message ---
--- Begin Message ---
Good Question. After reading this list for about a year I decided I would
not build a conversion until a better alternative to lead acid batteries
was available. I need to commute 45 miles round trip a day in hilly New
England terrain and would want heat also in winter. The economics of lead
acid and the thought of becoming an accolyte in the Religion of Battery
Management just won't cut it for me.
If a factory built car like the Phoenix Motorcars models or Tesla's
planned consumer level model were available with advanced batteries, I'd
order one immediately if it was available for a price in the same range as
the premium + base your talking about. I agree with your criteria - it
would need at least 100 mile range, 150-200 would be better, and would
need to be highway capable to interest me. I would add that the battery
pack would have to be guaranteed for 100,000 miles if used with the
charger supplied with the car. It would also be nice to be offered a
trade-in plan on a spent pack or an upgrade option. I can dream, can't I?
EV hungry,
John
> With the recent threads of people wanting to build their own hybrids I
> can't
> help but ask myself why? This is as I look out at my 2001 Honda Insight
> that I bought brand new and still love. I always wonder why these hybrid
> folks want to roll their own when they can just go out and buy one
> straight
> from the factory. I know the main reason is because they want to build a
> plug in hybrid. Still, I am doubtfull that they can come up with
> something
> anywhere close to as good as the hybrids that can't be plugged in but can
> be
> purchased at a dealers lot.
>
> It leads me to the question of what you would do if you could buy a
> factory
> EV. Let's say it was like the hybrids that you can buy now that come at a
> premium. I think the hybrid system on a Honda usually costs about $4000.
> It's hard to say exactly because they usually throw in a bunch of upscale
> options as well to kind of hide some of the cost, but let's go with that
> marketing model. If you could buy a factory built Civic, Accord, Camary,
> S10 truck etc... that was just like it's ICE counterpart, but you had to
> pay a premium for, what would you buy, and how much more would you be
> willing to pay? Would that be the end of EVs as conversions, or would the
> type of people that haunt this list rather continue to roll their own?
>
> I know for me, I would love to have a nice mid size sedan and would gladly
> pay up to a $10,000 premium, but only if it had 150 - 200 mile range.
> Although I certainly don't need this much range everyday, it is a
> reflection
> of some of the longer trips I would still want to be able to take. If it
> only had a 50 - 100 mile range that would make it more of a specialty car
> that I'm not sure I would be willing to pay any kind of premium for.
>
> damon
>
> _________________________________________________________________
> Picture this share your photos and you could win big!
> http://www.GETREALPhotoContest.com?ocid=TXT_TAGHM&loc=us
>
--- End Message ---
--- Begin Message ---
At 08:42 AM 6/29/2007, you wrote:
I was just thinking in general, something that would be able to do
something and be useful. I have two starter motors and was hoping to take
the apart and see if I could make them into a motor that worked. Was hoping
that might be a nice website on the basics of building a practical motor.
Most on the web are variations of the old Boy Scout motor that you were
suppose to build without benefit of a kit.
<http://www.eas.asu.edu/~holbert/wise/dcmotor.htm>http://www.eas.asu.edu/~holbert/wise/dcmotor.htm
For a usable motor Lindsay has some cheap books. He does have some books
that are not listed on the web, you have to order the catalog.
http://www.lindsaybks.com/bks5/dynamo/index.html
http://www.lindsaybks.com/bks3/armature/index.html
This is not really plans for building but has lots of drawings of early
motors, some detailed enough you could duplicate them.
<http://books.google.com/books?id=3ochAAAAMAAJ>http://books.google.com/books?id=3ochAAAAMAAJ
__________
Andre' B.
__________
Andre' B. Clear Lake, Wi.
--- End Message ---
--- Begin Message ---
The good news is you can get a lot of work done on your conversion without
the controller. In fact you can have it all done and tested and plunk the
controller in last. It just takes a 12 volt battery or two and a pair of
jumper cables to make that first drive. Twenty weeks can go by quite fast
if you are trying to squeeze in conversion time around an already busy life
:-)
damon
From: Matthew Drobnak <[EMAIL PROTECTED]>
Reply-To: ev@listproc.sjsu.edu
To: ev@listproc.sjsu.edu
Subject: Made the first step recently...
Date: Fri, 29 Jun 2007 07:04:40 -0400
On Thursday, the 27th, I ordered a Zilla 2k, 300 V controller....with an
estimated 20 week lead time. :-/
The good news is that I'll have a controller that'll kick butt. The bad
news is it will take a while.
Approx lead time on PHET batteries is a month. I've read 2-3 weeks on the
motor. So, by far, this is the longest wait.
On my way to being an EVer,
-Matt
_________________________________________________________________
Dont miss your chance to WIN $10,000 and other great prizes from Microsoft
Office Live http://clk.atdmt.com/MRT/go/aub0540003042mrt/direct/01/
--- End Message ---
--- Begin Message ---
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--- End Message ---
--- Begin Message ---
If I design my own adapter and have a machine shop make it is there
some documentation, instructions, plans or something that I can get on
exactly what to do?
I am completely lost :(
The only adapter I have made is to align the motor for a belt drive in
my trimmer mower :^) ...
and it has about and inch of tolerance:P
--
TEhben
'hElix EV'
evalbum: http://www.austinev.org/evalbum/1225
--- End Message ---
--- Begin Message ---
I figured I would be ready with 26 weeks to wait but it still took a
couple of weeks to get it running. There are no drawings for the
mounting holes and I had to fabricate the mounting brackets after the
unit arrived. Then the final wiring, etc......It worked the first
time I turned it on.........me
On 6/29/07, damon henry <[EMAIL PROTECTED]> wrote:
The good news is you can get a lot of work done on your conversion without
the controller. In fact you can have it all done and tested and plunk the
controller in last. It just takes a 12 volt battery or two and a pair of
jumper cables to make that first drive. Twenty weeks can go by quite fast
if you are trying to squeeze in conversion time around an already busy life
:-)
damon
>From: Matthew Drobnak <[EMAIL PROTECTED]>
>Reply-To: ev@listproc.sjsu.edu
>To: ev@listproc.sjsu.edu
>Subject: Made the first step recently...
>Date: Fri, 29 Jun 2007 07:04:40 -0400
>
>On Thursday, the 27th, I ordered a Zilla 2k, 300 V controller....with an
>estimated 20 week lead time. :-/
>
>The good news is that I'll have a controller that'll kick butt. The bad
>news is it will take a while.
>
>Approx lead time on PHET batteries is a month. I've read 2-3 weeks on the
>motor. So, by far, this is the longest wait.
>
>
>On my way to being an EVer,
>-Matt
>
_________________________________________________________________
Don't miss your chance to WIN $10,000 and other great prizes from Microsoft
Office Live http://clk.atdmt.com/MRT/go/aub0540003042mrt/direct/01/
--- End Message ---
--- Begin Message ---
----- Original Message -----
From: "Dan Frederiksen" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Friday, June 29, 2007 8:20 AM
Subject: Re: Motor weight
Phil Marino wrote:
In a sense, natural selections works for manufactured products. If it
were possible to make lighter, cheaper series motors with the same
performance, someone would already be making them and successfully
selling them. And, the current, poor design, would have disappeared
from the marketplace.
Hi
I'm not sure that's entirely true. seems to me some markets are very
conservative. even semi fancy markets like boeing and airbus are now
switching to composite materials when those are far from new. the
electromotor market seems extremely conservative to me
Dan
Hi Dan;
Yeah! I know what ya feel, looking at the heavy field piece of a DC
motor. I felt the same way, with an old Elwell Parker forktruck motor in
Taiwan. I took it apart and hasd a machine shop make me a nice thin housing.
Figgured the coils and pole pieces would/did the job. WRONG! The motor was
BEAUTIFUL, when I put it back together but was wofully underpowered! Wasn't
worth a damn to RUN anything. I shouldsa listened to the Chinese machinest,
he was TRYING to tell me this, but my Chinese comprehension wasn't that
good<g>!
So the heavy field piece is there for a REASON!Ya want a light motor ya go
AC and a zillion RPM~! When I first saw a Solectria Force I asked if that
was the Windshield wiper motor? The one that ran the car. Cute, petite,
who-are-they-kidding?But it was light and small, compared with the
ironmongery if a DC machine.
General Murders did it right in EV 1!Cute little Monster Motor there,
too.
Motoring along
Bob
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--- End Message ---
--- Begin Message ---
From: James Drysdale <[EMAIL PROTECTED]>
Reply-To: ev@listproc.sjsu.edu
To: ev@listproc.sjsu.edu
Subject: Re: electric bicycle - need help
Date: Fri, 29 Jun 2007 21:57:37 +0800
G'day Peter,
Yeah, last time I checked the local law, powered bicycles could only
legally put out a maximum of 200W.
But I'm also planning a semi-large trip (one-way 1600 km / 994 miles) in
December.
As in, long lonely country roads, so it's not like I'll be using it to
speed through school zones like a dickhead.
Aerodynamic Drag goes up as the cube of your speed.
Really? I thought it was the *square* of the speed. Glad you mentioned
that. It's good to be proven wrong sometimes.
You and the other bloke Mike have been quite helpful.
You were right.
The air drag (force - in pounds, for example) rises as the square of the
speed.
The POWER required to overcome this drag force rises as the cube of the
speed, because power is force x velocity. The extra velocity multiplier
brings the power up to the cube of velocity.
This is an approximation, but a very good approximation for typical speeds
of land vehicles.
Phil Marino
Thanks.
Regards,
James Drysdale.
Peter VanDerWal wrote:
> Well, I assume you are aware that such a bicycle won't be legal on the
roads?
>
> Now that we have that niggling detail out of the way. Bicycles have
> pretty bad aerodynamics (compared to other vehicles).
> Not much of an issue at 20-30kph, but significant at 80 kph.
>
> 750W will be good up to perhaps 50-60kph on flat level ground with no
> wind. Of course getting to this speed will take a while, though
> acceleration from 0-25kph should be quite brisk.
> Note most human beings can put out almost 750W for a very breif time
(less
> than a minute?)
> The average human can put out about 100 watts for an hour or so, a very
> fit person can produce 200-250 watts for an hour or so.
> It takes roughly 200 watts to go 30 kph on flat ground with no wind.
> Aerodynamic Drag goes up as the cube of your speed.
>
> Getting up to 80kph will require at least twice and probably three times
> as much. Figure at least 2,000 watts.
>
>
>> G'day all,
>>
>> Not an electric automobile, but an electric vehicle nonetheless.
>> I'd like to create a hybrid muscle-electric bicycle.
>>
>> But I need some help.
>> 1) Trying to work out how much *power* a specific 750W will actually
>> give me.
>>
>> Power = (force * displacement) / time
>> Force = mass * acceleration
>> I am stuck, insufficient info and/or knowledge.
>>
>> 2) To move my fully-laden bicycle up to a speed of 80km/h
>> (49.67miles/h), how powerful a motor will I need?
>>
>> Information I do have......
>> mass = 120kg
>> desired velocity = 22.2 m/s (80km/h or 49.67 miles/h)
>>
>> Where I am stuck is in the acceleration & force equations.
>> I do not know how much acceleration and max forward velocity I can
>> achieve with a 750W motor.
>>
>> This is the motor in question!!!
>>
https://www.electricscooterparts.com/ShoppingCart.asp?ProductCode=MOT-36750G
>> >From this page.
>> http://www.electricscooterparts.com/motors.html
>> 36volt
>> 750watt
>> 2500rpm geared down to 420rpm
>>
>> I realise that there are other factors here that need addressing, like
I
>> said, I need help.
>> Is it okay to disregard factors such as wind resistance for now?
>> Wind resistance increases as the square of the velocity or something
>> like that.....
>>
>>
>> Cheers all,
>> James Drysdale.
>>
>>
>>
>
>
>
_________________________________________________________________
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--- Begin Message ---
I'm not 100% sure, but I think that it is bad to just have a couple
dozen chargers go off all at once. You'd need a system to control it
all. Are there chargers that can be programed to charge such a
high-voltage yet low-amp-hour pack? Manzanita Micro? Zivan?
On 6/29/07, Rob&Amy Smith <[EMAIL PROTECTED]> wrote:
Can anyone give me a synopsis of the current thinking on NiMH packs?
What I have gathered from reading the list for a while now (are these
true statements?):
1. Charging or discharging multiple cells in parallel is generally a
bad idea.
2. Charging or discharging long strings quickly gets cells out of
balance.
3. Finishing voltage is not a good indicator of charge complete.
4. Watching for -dv/dt turn is better indicator
5. Monitoring for cell temp rise can also be a good indicator of
charge complete
6. Previous cycle charge/discharge info is best indicator.
So, lets say I want to build a ~200V/40Ah pack out of 4 strings of
10Ah cells (not full EV size I realize)
For charging I was considering borrowing ideas from the EV AGM guys
and the RC NiMH guys. I really like the AGM balance idea of just
running multiple small independant isolated chargers to make sure
each battery is balanced. This gets tricky here though, as we have
potentially ~667 cells. The RC guys seem to pretty routinely fast
charge 7.2-9.6V strings with good results. There are 5A "smart" -dv/
dt based chargers available in the $40-$50 price range, which should
charge a 10Ah 7.2V ministring in ~2 hrs. Since in the this case we'd
still have 112 of these ministrings, the last component would be a
relay switch matrix and a controller. The simplest implementation
would probably be to have one charger per ministring in the string,
in this case 28. Then each charger would be responsible for charging
4 ministrings (one from each string) which should complete
overnight. Ideally thermal sensors would be used to monitor for
problems, but this could add alot of complexity. Maybe some simple
bimetal switches, simple thermistor/comparator circuits to provide
digital feedback rather than analog. Otherwise some sort of big
analog mux matrix would probably be needed due to the large number of
analog inputs you'd have to deal with. This is not cheap, we're
probably talking $1100 for chargers (maybe can find a volume discount
somewhere, or look at chinese rather than german chargers) plus
needing something to control it all (I'm thinking an old laptop and
DIO box?) and a big bunch of relays. On the other hand, what other
options are there in this price range?
For discharging, I'm less sure. Can you parallel the big strings
during discharge? Maybe if you use the above temp sensors and drop
strings if there is any signs of cells heating up? Otherwise I was
thinking of monitoring string voltage and switching through the
strings sequentially as each starts to roll off from its flat part of
the curve. I think I need some help here LOL!
Any thoughts or comments much appreciated,
Rob
Phoenix, AZ
--- End Message ---
--- Begin Message ---
Chet Fields wrote:
I am progressing quite well on my controller design and now have a couple of
specific questions
that you all might be able to help me with.
After reading recently about different throttle behavior I have rethought the
way I am doing it. I
was just letting the level of input from the pot translate into a percentage of
duty cycle (with
current limiting and low voltage just reducing it). However, now I thought
maybe I should approach
it from the angle of the input establishing a desired current level and then
have a circuit that
would compare that to the actual via an op-amp at maximum gain that would then
either charge or
discharge a capacitor through a resistor that would then be the actual signal
for the PWM
percentage. I thought of this as I was designing my regen circuit off of the
brake signal. But I
guess it would also work just as well for the accelerator side as well.
My first question is: Do opamps allow you to sink as well as source the
current? In other words,
when the opamp output is 0v will it drain the capacitor and allow the voltage
to drop?
Yes.
And the second is this: Will this control be fast enough to limit current etc.
Or should I also
have at a later stage some mechanism that will actually shut off the output to
the gate drive
input when the current exceeds my maxlimits?
Depends on how you design it. You're getting into feedback control
theory. It might help you considerably to do some research on PID
control techniques.
There's a difference between current limit and current regulation. For
your throttle response, it sounds as if you want current regulation.
i.e, 50% throttle translates to 50% current, or some such. Current
limit is primarily to prevent damage, and there's no reason you cannot
have a separate fast-response current limit sense as a failsafe.
I'm doing a bit of controller design myself. There is a current
amplifier for doing "normal" current limiting and throttle response
(user settable current limit), and there's a separate circuit that uses
an ultra-fast comparator for "overcurrent" conditions, which would kill
the PWM completely, until reset.
--- End Message ---
--- Begin Message ---
Because there are so many different transmissions, there are so many
different adaptors. You could contact someone who has made an adaptor
for the same car you are converting through evalbum.com or some
personal blogs.
On 6/29/07, Tehben Dean <[EMAIL PROTECTED]> wrote:
If I design my own adapter and have a machine shop make it is there
some documentation, instructions, plans or something that I can get on
exactly what to do?
I am completely lost :(
The only adapter I have made is to align the motor for a belt drive in
my trimmer mower :^) ...
and it has about and inch of tolerance:P
--
TEhben
'hElix EV'
evalbum: http://www.austinev.org/evalbum/1225
--- End Message ---
--- Begin Message ---
http://www.grassrootsev.com sells some excellent videos on how to make an
adaptor. Even if you don't do it exactly that way you'll learn alot.
http://www.metricmind.com also is excellent in detailing how Victor made his
adaptor.
I did my adaptor design in Emachine shop, and it was significantly more
expensive than buying one from http://www.electroauto.com/ .
----- Original Message ----
From: Tehben Dean <[EMAIL PROTECTED]>
To: ev@listproc.sjsu.edu
Sent: Friday, June 29, 2007 9:55:44 AM
Subject: Re: Adapter Problem
If I design my own adapter and have a machine shop make it is there
some documentation, instructions, plans or something that I can get on
exactly what to do?
I am completely lost :(
The only adapter I have made is to align the motor for a belt drive in
my trimmer mower :^) ...
and it has about and inch of tolerance:P
--
TEhben
'hElix EV'
evalbum: http://www.austinev.org/evalbum/1225
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--- Begin Message ---
> Aerodynamic Drag goes up as the cube of your speed.
>
> Really? I thought it was the *square* of the speed.
That one gets me all the time too. The power needed to overcome drag goes
up as the cube of the speed.
However, the energy needed to go a certain distance goes up as the square
of the speed, because it only takes you have as long to get there when you
go twice as fast.
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If you send email to me, or the EVDL, that has > 4 lines of legalistic
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