EV Digest 6065
Topics covered in this issue include:
1) RE: Cursit controllers revisited (squealing); precharge 'circuit' again
(please)
by "Roger Stockton" <[EMAIL PROTECTED]>
2) RE: EV controllers? the 4th option...
by "Roger Stockton" <[EMAIL PROTECTED]>
3) RE: clutch release bearing
by "Roger Stockton" <[EMAIL PROTECTED]>
4) Re: Splined Adapters, Was: Inexpensive DC Motors with Keyed Shafts
(Correction)
by Eric Poulsen <[EMAIL PROTECTED]>
5) Re: 72V Power Supply - Can I build one?
by "Peter VanDerWal" <[EMAIL PROTECTED]>
6) Re: EV controllers? the 4th option...
by "Stefan T. Peters" <[EMAIL PROTECTED]>
7) Re: Mechanical control, was: Re: EV controllers? the 4th option...
by GWMobile <[EMAIL PROTECTED]>
8) Re: 72V Power Supply - Can I build one?
by "Lawrence Rhodes" <[EMAIL PROTECTED]>
9) Re: 72V Power Supply - Can I build one?
by "martin emde" <[EMAIL PROTECTED]>
10) RE: Mechanical control, was: Re: EV controllers? the 4th option.
..
by Cor van de Water <[EMAIL PROTECTED]>
11) Inrush current, was: Cursit controllers revisited (squealing); pr
echarge 'circuit' again (please)
by Cor van de Water <[EMAIL PROTECTED]>
12) Re: Mechanical control, was: Re: EV controllers? the 4th option...
by "Dave Wilker" <[EMAIL PROTECTED]>
13) inexpensive, homebuilt, Contactor Controller...
by "jerryd" <[EMAIL PROTECTED]>
14) Re: Mechanical control, was: Re: EV controllers? the 4th
option...
by James Massey <[EMAIL PROTECTED]>
15) Re: Mechanical control, was: Re: EV controllers? the 4th
option...
by Lee Hart <[EMAIL PROTECTED]>
16) Re: inexpensive, homebuilt, Contactor Controller...
by "Ev Performance (Robert Chew)" <[EMAIL PROTECTED]>
17) Re: Mechanical control, was: Re: EV controllers? the 4th option...
by Jeff Shanab <[EMAIL PROTECTED]>
--- Begin Message ---
Cor van de Water wrote:
> Whether you use one battery or a string of many should
> not matter for Isc (short circuit current) as with each
> extra wire and internal battery resistance, you also
> increase the voltage sufficient to give the same current
> as with one battery.
This is true.
> The ESR of the cap does not change though, so the effect of
> the cap's ESR becomes less significant with higher pack
> voltage.
This is also true.
> I deliberately neglected the ESR, contactor resistance, fuse
> resistance, breaker resistance and wire resistance, because
> all that should be small compared to the pack internal resistance.
This is, I believe, your mistake. The better the battery (lower
impedance), the *more* significant the pack's external resistance (and
inductance) becomes with respect to reducing the magnitude of that peak
inrush current.
The current will still be several hundreds of amps, perhaps even over
1000A, but it will be well below the 3000A figure you suggested.
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
Cor van de Water wrote:
> In fact, there have already been two generations of
> switching controllers: SCR without the benefits of
> high frequent switching (squeal) and current multiplication
> (more battery current).
Actually, both of these are incorrect ;^>
SCR controllers (the commonly available GE EV1's) switch at such low
frequency that they don't squeal, they growl. This may seem like
splitting hairs, but once you've heard the SCR growl vs the Curtis
1.5kHz squeal, you'll understand.
Also, the SCR controllers most certainly do provide current
multiplication; they are still a buck converter, just using SCRs that
have to be switched at low speed instead of MOSFETs or IGBTs that
support higher switching frequencies. GE's literature states that the
average motor loop current is typically 2-3x the battery current. The
modern controllers certainly do do a better job at this, however.
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
John wrote:
> The service manual shows a cut away of the bearing holder
> with instructions to grease a recess on the the inside
> that contacts the transmission input shaft. As I understand
> it, the transmission input shaft spins inside the bearing
> holder so it seems the significantly smaller area on the
> bearing may be problematic.
Gotcha. As long as the input shaft can spin freely inside of the
throwout bearing you should be fine.
> I don't have a bearing puller so unless I want to buy another tool, I
> need to get a replacement bearing/holder combination.
I've yet to see an throwout bearing that you could disassemble (and have
it be usable afterwards ;^), so don't worry about buying another tool as
its not an option. I suppose you could try ordering a bearing from
another aftermarket parts place and if you still aren't happy with wht
you get, there is always the dealer.
Good luck,
Roger.
--- End Message ---
--- Begin Message ---
Eric Poulsen wrote:
Bruce wrote:
Which Surplus Center motor did you get? Was it their part #
10-1422? How
did it work out?
No, I went with the other option, the 10-1422. It's a 7" diameter
series-wound motor. 48V, 5.6HP. The shaft is a 1.25" 14T splined job.
It's dirty, and
I mean YES, I did get the 10-1422. For some reason, I read what you
wrote and in my mind it was the 10-2120, which is the one Lee Hart
mentioned originally.
--- End Message ---
--- Begin Message ---
Naw, you're going about this all wrong. If all you want to do is make
sure the mechanicals and the motor works, then all you need is One(1) car
battery.
You don't need 72V unless you are looking at going 25mph. 12V will get
you up to about 4-5 mph, plenty fast enough for testing and WAY cheaper
than a big transformer and and rectifier. Safer too, no cord trailing
around.
> Greetings,
> I have a GEM NEV that is in disrepair. I have all the parts (less the
> batteries), schematic, and manual and would like to see if I can get it
> going. I'd like to troubleshoot the car without having to invest in the
> batteries, and then later find that the controller or circuit board is
> fried. Is it possible to build an inexpensive, 72V power supply that
> would
> source enough current to power -up the car and maybe turn the wheels under
> no load? Maybe a large transformer and bridge rectifier? If you know of
> a
> design (schematic and parts list) or any other solutions I would
> appreciate
> it.
> Thanks.
> Martin
>
>
--
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 ---
Lee Hart wrote:
From: Rich Rudman
This is exactly what I am proposing... High voltage Curtis Killer, with
some goodies, not many... 96V to perhaps 192V... 500 amp... is going
to cover most anyone who would have bought this controller instead
of a Curtis... I am proposing an IGBT module based machine.
IGBTs are generally good for higher voltages and lower currents than
this. Your controller will have on the order of a 3v drop; that's 1500 watts
at 500 amps. Dissipating 1500 watts takes some pretty impressive (and
expensive) heatsinks.
Under 200v, I'd prefer MOSFETs. Use them for both the transistors and
freewheel diodes (synchronous rectification). This will get the drop under 1v,
which mean 1/3rd the heat to get rid of.
Modules are really nice because they get rid of dozens of tiny little devices that must
be meticulously wired in parallel. A controller like this would need a dual MOSFET
"half bridge" module.
Would a couple of these work well for a PWM controller?
http://www.st.com/stonline/products/literature/ds/7738/ste110ns20fd.pdf
...
rev limiter (and a tach drive output sure would be nice)
For a simple "black box" controller, such functions should be simple
enough to add that it doesn't need to be designed and integrated into
the controller. For instance, the controller might just have an "inhibit"
input that shuts it down if it exceeds X volts. The user could work out
circuits to apply a voltage proportional to RPM, or temperature, or
whatever.
Nice... BTW there are a ton of these "modules" with sensors that put out
12V already available. They are used for racers/hotrodders in
conjunction with idiot lights & safety shutdowns & various selenoids
(shifter, thottle linkage, etc). So I would add that the inhibit input
should take a > 4.5v < 15v range.
--- End Message ---
--- Begin Message ---
Tell more about the contact controller.
Please realize one of my goals is to keep it home built and simple.
I want to stay away from things that require huge labs and factories
like semiconductors.
I believe that while not the most perfect , an electric car that could
literally be made from a home builder including homebuilt batteries
would have a whole new level of appeal even if it only did a 20 mile
round trip.
Ok maybe you have to buy the motor off ebay but everything else can
perhaps be built or adapted from low tech components.
By the way mit recently came out with a cheap solar heat powered
electric generator using a solar concentrator, power sterring pumps
running off solar heated freon and linked to a good old car generator to
charge batteries.
With great efficiencies and very low cost compared to solar cells why
could that sit in an electric pickup truck and give great self
rechargability?
That's the kind of ultra low tech I want to aim for.
On Wed, 25 Oct 2006 9:04 pm, Lee Hart wrote:
It'd work, just be exceptionally inefficient if you tried to do it
with a
series motor. Instead of having 80% of the battery available energy
turned into motion, you may be as bad as 30%.
From: "Ted C."
What's the problem with that? Millions of people every day drive cars
powered by ICE motors every day. We don't hear to many of them
complain about 30% efficiency.
An ICE has a range of perhaps 300 miles even with its 30% efficiency.
If its engine was 100% efficient, its range would be more like 1000
miles
on a tank of gas.
An EV has a range of more like 30 miles, and that's *with* an
efficiency
of 80% or more. If its efficiency were 30%, its range would be more
like
10 miles. That's unacceptable.
I think what you're looking for is a contactor controller. This is what
they
used 100 years ago for EVs. They are crude and jerky, but almost 100%
efficienct and very simple. Basically, it is a bunch of switches that
wire
the batteries in various series/parallel combinations to get the
desired
motor speed.
www.GlobalBoiling.com for daily updated facts about hurricanes,
globalwarming and the melting poles.
www.ElectricQuakes.com daily solar and earthquake data.
--- End Message ---
--- Begin Message ---
Just get some used batteries 6 12 volt batteries will do. Test your system
that way. My favorite(Excess Solutions in Milpitas, CA) was selling some
7ah battereis for 5 buck each that might do. There were also some 2 ah
batteries that might work. Pick them up locally if you can. I measured all
the batteries to get two strings of 36v for some scooters. Lawrence
Rhodes......
----- Original Message -----
From: "Cor van de Water" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Wednesday, October 25, 2006 4:44 PM
Subject: RE: 72V Power Supply - Can I build one?
> See if you can find (or already have) a transformer that
> supplies 48V or so, you can even use a transformer that is
> used by people moving from abroad - they are pretty cheap
> at Frys and similar outlets, but instead of connecting
> the 110 side to the wall outlet to make 220V, you connect the
> 220 side to the 110V wall outlet, so the 110 side now has 55V.
> Make sure it is a heavy transformer - probably need more than
> 500 Watt to avoid burning up the transformer.
>
> Run the output of the transformer through a bridge rectifier
> and - dependent on whether the controller already has large
> capacitors on its input - you may want to add some large
> 80V or 100V capacitors between the + and - output of the
> bridge rectifier.
>
> Another alternative that may be even more realistic is to
> go to a local golf club or other place where they service
> the golf carts and ask if you can have a removed pack
> for testing your cart.
> It may not be good, but will likely allow you to test and
> even drive (albeit with shortened range) your cart.
> This latter solution should cost you little to nothing.
>
> Success,
>
> Cor van de Water
> Systems Architect
> Email: [EMAIL PROTECTED] Private: http://www.cvandewater.com
> Skype: cor_van_de_water IM: [EMAIL PROTECTED]
> Tel: +1 408 542 5225 VoIP: +31 20 3987567 FWD# 25925
> Fax: +1 408 731 3675 eFAX: +31-87-784-1130
> Proxim Wireless Networks eFAX: +1-610-423-5743
> Take your network further http://www.proxim.com
>
>
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> Behalf Of martin emde
> Sent: Wednesday, October 25, 2006 4:20 PM
> To: [email protected]
> Subject: 72V Power Supply - Can I build one?
>
>
> Greetings,
> I have a GEM NEV that is in disrepair. I have all the parts (less the
> batteries), schematic, and manual and would like to see if I can get it
> going. I'd like to troubleshoot the car without having to invest in the
> batteries, and then later find that the controller or circuit board is
> fried. Is it possible to build an inexpensive, 72V power supply that
would
> source enough current to power -up the car and maybe turn the wheels under
> no load? Maybe a large transformer and bridge rectifier? If you know of
a
> design (schematic and parts list) or any other solutions I would
appreciate
> it.
> Thanks.
> Martin
>
--- End Message ---
--- Begin Message ---
Actually I already connected the motor to a 12v battery to verify that the
motor works. It's the motor/controller interface that I'm concerned with.
I have a feeling the controller has a lock-out and will not function if the
voltage is below some threshold, say 66V. Same with the circuit board that
includes the DC-DC converter and other control. I kind of like the "find 6
old batteries at the junkyard" idea.
Thanks.
Martin
On 10/25/06, Peter VanDerWal <[EMAIL PROTECTED]> wrote:
Naw, you're going about this all wrong. If all you want to do is make
sure the mechanicals and the motor works, then all you need is One(1) car
battery.
You don't need 72V unless you are looking at going 25mph. 12V will get
you up to about 4-5 mph, plenty fast enough for testing and WAY cheaper
than a big transformer and and rectifier. Safer too, no cord trailing
around.
> Greetings,
> I have a GEM NEV that is in disrepair. I have all the parts (less the
> batteries), schematic, and manual and would like to see if I can get it
> going. I'd like to troubleshoot the car without having to invest in the
> batteries, and then later find that the controller or circuit board is
> fried. Is it possible to build an inexpensive, 72V power supply that
> would
> source enough current to power -up the car and maybe turn the wheels
under
> no load? Maybe a large transformer and bridge rectifier? If you know
of
> a
> design (schematic and parts list) or any other solutions I would
> appreciate
> it.
> Thanks.
> Martin
>
>
--
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 ---
Contactor controller is good to home-brew.
Forget homebrew batteries, unless you have a huge lab.
GolfCart batteries are cheap, reliable, have a decent
lifetime and capacity, this cannot be beaten with
anything you build at home.
It is like lamps - you don't go blow glass and put
filaments in to make lamps, you buy them.
You also do not go and pour some rubber to make
tires, you buy them.
Battery chemistry is so complex to get it right,
that it will take you a long time to make batteries
that last longer than a month, are reliable and
have decent capacity.
Also, they will not be cheaper than GolfCart batteries
so why bother?
Anyway, with a motor, batteries, fuse, breaker and
a contactor controller you can make a decent low-speed
vehicle.
See for an example schematic here:
http://www.aaroncake.net/circuits/cntctcon.htm
Cor van de Water
Systems Architect
Email: [EMAIL PROTECTED] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [EMAIL PROTECTED]
Tel: +1 408 542 5225 VoIP: +31 20 3987567 FWD# 25925
Fax: +1 408 731 3675 eFAX: +31-87-784-1130
Proxim Wireless Networks eFAX: +1-610-423-5743
Take your network further http://www.proxim.com
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of GWMobile
Sent: Wednesday, October 25, 2006 11:39 PM
To: [email protected]
Cc: [EMAIL PROTECTED]
Subject: Re: Mechanical control, was: Re: EV controllers? the 4th
option...
Tell more about the contact controller.
Please realize one of my goals is to keep it home built and simple.
I want to stay away from things that require huge labs and factories
like semiconductors.
I believe that while not the most perfect , an electric car that could
literally be made from a home builder including homebuilt batteries
would have a whole new level of appeal even if it only did a 20 mile
round trip.
Ok maybe you have to buy the motor off ebay but everything else can
perhaps be built or adapted from low tech components.
By the way mit recently came out with a cheap solar heat powered
electric generator using a solar concentrator, power sterring pumps
running off solar heated freon and linked to a good old car generator to
charge batteries.
With great efficiencies and very low cost compared to solar cells why
could that sit in an electric pickup truck and give great self
rechargability?
That's the kind of ultra low tech I want to aim for.
On Wed, 25 Oct 2006 9:04 pm, Lee Hart wrote:
>>> It'd work, just be exceptionally inefficient if you tried to do it
>>> with a
>>> series motor. Instead of having 80% of the battery available energy
>>> turned into motion, you may be as bad as 30%.
>
> From: "Ted C."
>> What's the problem with that? Millions of people every day drive cars
>> powered by ICE motors every day. We don't hear to many of them
>> complain about 30% efficiency.
>
> An ICE has a range of perhaps 300 miles even with its 30% efficiency.
> If its engine was 100% efficient, its range would be more like 1000
> miles
> on a tank of gas.
>
> An EV has a range of more like 30 miles, and that's *with* an
> efficiency
> of 80% or more. If its efficiency were 30%, its range would be more
> like
> 10 miles. That's unacceptable.
>
> I think what you're looking for is a contactor controller. This is what
> they
> used 100 years ago for EVs. They are crude and jerky, but almost 100%
> efficienct and very simple. Basically, it is a bunch of switches that
> wire
> the batteries in various series/parallel combinations to get the
> desired
> motor speed.
www.GlobalBoiling.com for daily updated facts about hurricanes,
globalwarming and the melting poles.
www.ElectricQuakes.com daily solar and earthquake data.
--- End Message ---
--- Begin Message ---
Roger,
Do you realize what you said?
Let me do a quick calculation, based on my pack's parameters
and my truck's max current draw (only 250A) and you will see
how ridiculous (sorry for the strong language) your statement is.
My pack is 312V.
Suppose that it would deliver 1000A when short-circuited.
that means we have 312/1000 = 0.312 Ohm of series resistance
in the wiring and batteries and such.
Since each battery is 4 mOhm, the 26 batteries have 0.104 Ohm
So the wiring, breaker, contactor and fuse must add 0.208 Ohm.
What does that mean during driving?
250A in 0.208 Ohm cause a voltage drop of 52 Volts.
This causes a heat production of 13 kW.
So, with 26 batteries we have 27 interconnecting cables and
each cable will be heated like a torchiere with almost 500 Watt???
No way.
In fact, I have actually measured the resistance of each cable in
my truck.
I trashed two pre-made cables because their resistance was way
too high. Most cables were close to 1 mOhm but these two were
8 and above 12 mOhm IIRC, so these two would indeed have
behaved as I calculated above.
But with good cables (and clean contacts) each element should
not need to add more than 1 mOhm, so total resistance better be
close to 104 mOhm (batteries) + 27 mOhm (cables) + 3 mOhm
(breaker, contactor, fuse) = 134 mOhm
Since freshly charged batteries sit around 13V (mine actually
at 13.25V) a short-circuit of this pack through 134 mOhm
results in a little over 2500 Amp current.
Then we need to factor in the ESR of the caps that are charged
in parallel, so their total ESR is the impedance per cap divided
by the number of caps. I think someone mentioned 22 mOhm per cap
so we can expect the total ESR to be in the order of 5 mOhm.
This drops the initial inrush current by less than 100 Amp to
a value over 2400 Amps
The difference with my initial value is not so big, that is
why I started with neglecting all secondary effects, as they
will make things a lot more complicated without significant
changes to the rough first-order number, as long as you
make sure that you are not accidentally neglecting a big
influence.
Regards,
Cor van de Water
Systems Architect
Email: [EMAIL PROTECTED] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [EMAIL PROTECTED]
Tel: +1 408 542 5225 VoIP: +31 20 3987567 FWD# 25925
Fax: +1 408 731 3675 eFAX: +31-87-784-1130
Proxim Wireless Networks eFAX: +1-610-423-5743
Take your network further http://www.proxim.com
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Roger Stockton
Sent: Wednesday, October 25, 2006 9:32 PM
To: [email protected]
Subject: RE: Cursit controllers revisited (squealing); precharge
'circuit' again (please)
Cor van de Water wrote:
> Whether you use one battery or a string of many should
> not matter for Isc (short circuit current) as with each
> extra wire and internal battery resistance, you also
> increase the voltage sufficient to give the same current
> as with one battery.
This is true.
> The ESR of the cap does not change though, so the effect of
> the cap's ESR becomes less significant with higher pack
> voltage.
This is also true.
> I deliberately neglected the ESR, contactor resistance, fuse
> resistance, breaker resistance and wire resistance, because
> all that should be small compared to the pack internal resistance.
This is, I believe, your mistake. The better the battery (lower
impedance), the *more* significant the pack's external resistance (and
inductance) becomes with respect to reducing the magnitude of that peak
inrush current.
The current will still be several hundreds of amps, perhaps even over
1000A, but it will be well below the 3000A figure you suggested.
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
Instead of dissipative current control, can you use switching/chopper type
control?
David C. Wilker Jr.
USAF (RET)
----- Original Message -----
From: "James Massey" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Wednesday, October 25, 2006 7:04 PM
Subject: Mechanical control, was: Re: EV controllers? the 4th option...
At 04:28 PM 25/10/06 -0700, GWMobile wrote:
What is needed for a controller. (Not charger)
I mean the real basics.
Why not make a huge rheostat and hook it up to the batteries?
You could do it with a parralel series of graphite rods and big copper
brushes on a lever hinge.
They could handle a huge current load and voltage.
Nothing fancy just more or less juice to the motor just like a gas engine
pedal.
Revlimiting could be done mechanically with a rev sensor disengaging the
rheostat with a servo motor.
Why wouldn't this work?
It'd work, just be exceptionally inefficient if you tried to do it with a
series motor. Instead of having 80% of the battery available energy turned
into motion, you may be as bad as 30%. And the price of the parts would
probably run out at more than a Curtis controller. Why so inefficient? If
your motor is needing 400A to accelerate, you start off with 120V pack
delivering 400A with 20V across the motor and the rest across the
rheostat, 100V @ 400A = 40kW, that's a big rheostat!. plus your battery
amps always equals motor amps, so puekert bites hard.
If you can find a shunt or sep-ex motor you can do that for field control,
and get reasonably efficient control. Do some research at 1920s EV
technology and you'll find what you're describing, but in ways that work
reasonably well. If you are mechanically clever, you can build a
centrifical 'gadget' that mounts the rheostat on it and prevents you from
having too little field at too low an RPM, giving current limit. If you
are not mechanically clever, someone could build you one for around, oh, I
dunno, the price of a Zilla? So just go out and buy a Zilla and get
something more compact, probably safer and more reliable.
Just my $0.02
RTegards
[Technik] James
--- End Message ---
--- Begin Message ---
HI GW and All,
----- Original Message Follows -----
From: GWMobile <[EMAIL PROTECTED]>
To: [email protected]
Cc: [EMAIL PROTECTED]
Subject: Re: Mechanical control, was: Re: EV controllers?
the 4th option...
Date: Wed, 25 Oct 2006 23:38:56 -0700
>Tell more about the contact controller.
>
>Please realize one of my goals is to keep it home built and
>simple.
>
>I want to stay away from things that require huge labs and
>factories like semiconductors.
I agree with you as I'm about to go to E
controllers for the first time, for the last 10 yrs I have
used only CC's.
They are made up of switches/contactors that
series/parallel the battery pack to different voltages, thus
vary the motors power output.
In low power EV's, you really only need/have 2
speeds, off and on except in parking lots, ect where you
need to go slow. Any speeds between that usually is just to
get to top speed. To vary speeds between these, you just
turn them on and off, depending on whether you need to go
faster or slower.
And since you need to limit the starting amps so
you don't break things, you use a starting resistor, easily
made from SS, other wire. For under 1500 lb EV's, get a golf
cart resistor series card and rewire them in parrallel is
about right, you can add, subtract to get the starting power
you want.
Field weakening, shorting the field some with say
a 12gge, 1' solid copper wire and a contactor, increases top
end power, speed and/or allows higher gearing.
A viable CC would then be 1 or 2 series/parallel
battery bank steps, a starting resistor and a field
weakening step or 2, giving 3 to 7 steps, is plenty smooth,
no different than a transmission shift when correctly sized.
And best, they have lots of power/amps naturally so
good starting torque for those times you need to start up a
hill, especially in EV's without transmissions, which would
need at least a 800 amp rating, price, to match it.
Citi-cars that replaced their CC's eith EC's were very
disappointed in their lack of power. Only when really high
amp EC's come around have they become viable in them except
in exceptionally flat places.
And the fact you can repair it yourself in a few
minutes by carrying a spare contactor or 2 and some
contacts, makes it a very good way to have an inexpensive,
reliable EV.
In my Ewoody, I was perfectly happy with just a
starting resistor and full power when it was at 45 mph and
36vdc. Resistor for starting, parking lots and on/off full
power at speeds above 10-20 mph. At 48 vdc and 60 mph, it
had too much power so needed another speed so went to
series/parallel the batts and field weakening to give me
field weakening speeds on 24 and 48 vdc and 48 vdc, for 3
more steps. If you have a lot of slow, stop and go driving,
pick the one with more S/P speeds.
Even if you have an EC, you should think about
putting in a parallel CC in case it fails, to get home. You
already have parts of it anyway to run the EC.
CC's have served well for 100+ yrs in commercial
use and a perfectly viable, some say better ;^D, controller
to use.
Jerry Dycus
>
>I believe that while not the most perfect , an electric car
>that could literally be made from a home builder including
>homebuilt batteries would have a whole new level of appeal
>even if it only did a 20 mile round trip.
>
>Ok maybe you have to buy the motor off ebay but everything
>else can perhaps be built or adapted from low tech
>components.
>
>By the way mit recently came out with a cheap solar heat
>powered electric generator using a solar concentrator,
>power sterring pumps running off solar heated freon and
>linked to a good old car generator to charge batteries.
>With great efficiencies and very low cost compared to solar
>cells why could that sit in an electric pickup truck and
>give great self rechargability?
>
>
>That's the kind of ultra low tech I want to aim for.
>
>
>
>On Wed, 25 Oct 2006 9:04 pm, Lee Hart wrote:
>>>> It'd work, just be exceptionally inefficient if you
>>>> tried to do it with a
>>>> series motor. Instead of having 80% of the battery
>>>> available energy turned into motion, you may be as bad
>>as 30%.
>> From: "Ted C."
>>> What's the problem with that? Millions of people every
>>> day drive cars powered by ICE motors every day. We
>>> don't hear to many of them complain about 30%
>>efficiency.
>> An ICE has a range of perhaps 300 miles even with its 30%
>> efficiency. If its engine was 100% efficient, its range
>> would be more like 1000 miles
>> on a tank of gas.
>>
>> An EV has a range of more like 30 miles, and that's
>> *with* an efficiency
>> of 80% or more. If its efficiency were 30%, its range
>> would be more like
>> 10 miles. That's unacceptable.
>>
>> I think what you're looking for is a contactor
>> controller. This is what they
>> used 100 years ago for EVs. They are crude and jerky, but
>> almost 100% efficienct and very simple. Basically, it is
>> a bunch of switches that wire
>> the batteries in various series/parallel combinations to
>> get the desired
>> motor speed.
>
>www.GlobalBoiling.com for daily updated facts about
>hurricanes, globalwarming and the melting poles.
>
>www.ElectricQuakes.com daily solar and earthquake data.
>
--- End Message ---
--- Begin Message ---
At 12:13 AM 26/10/06 -0700, David C. Wilker wrote:
Instead of dissipative current control, can you use switching/chopper type
control?
G'day David, and all
It would be possible to make a motorised chopper, but you would still need
to have a freewheel diode/diodes. You would need to be a careful driver,
since current limiting would be difficult to implement on a mechanical
sustem (but not impossible) so would be in the hands (foot) of the driver.
Last time this came up I had a think about it (but never posted it) and
came up with a concept where you could have a motorised segmented section,
like a commutator that has no windings attached. There would be a fixed set
of brushes and a moving set of brushes, that move one brush thickness
distance. The commutator segments would (i think) need be at least three
brush thicknesses wide. When the brushes are on adjoining segments (with a
gap between them equal to the thickness of the brushes), no current flows
as there is always a segment gap between the brushes. As the moving brushes
come further towards the fixed brushes, there will be more and more overlap
(on) time.
This would result in a fixed pulse frequency, pulse-width modulation
controller, with the frequency determined by the brush speed. The wider the
brushes are, the better, and I expect it would eat brushes if not careful
to keep the amps down as the current is all on the edges of the brushes.
An illustration, but without being able to draw the commutator arc follows:
0%PWM: At 0% a comm join is leaving the fixed brush as the join on the
other side of the comm segment is reaching the near side of the moving brush:
|///////////////
###############|///////////////
Fixed brush####|///////////////
###############|///////////////
###############|====Comm joint=
|///////////////
|///////////////
|///////////////
|//Comm segment/
|///////////////
|///////////////
|///////////////
|====Comm joint=
###############|///////////////
Moving brush####|///////////////
###############|///////////////
###############|//Comm segment/
|///////////////
50%PWM: At 50% a comm join is leaving the fixed brush as the join on the
other side of the comm segment is reaching the middle of the moving brush:
|///////////////
|//Comm segment/
###############|///////////////
Fixed brush####|///////////////
###############|///////////////
###############|====Comm joint=
|///////////////
|///////////////
|///////////////
|//Comm segment/
|///////////////
###############|///////////////
Moving brush####|///////////////
###############|====Comm joint=
###############|///////////////
|///////////////
100%PWM: At 100% a comm join is leaving the fixed brush as the join on the
other side of the comm segment is reaching the far side of the moving brush:
|///////////////
|//Comm segment/
###############|///////////////
Fixed brush####|///////////////
###############|///////////////
###############|====Comm joint=
|///////////////
|///////////////
|//Comm segment/
###############|///////////////
Moving brush####|///////////////
###############|///////////////
###############|====Comm joint=
|///////////////
Apart from the mechanical challenge of setting this up, and the lossed
involved in the motor that drives the PWM frequency, and the complete lack
of current limiting, there is no reason not to make something like this. 4
sets of segments on a 3000RPM motor would give a 200Hz switching frequency
(if I've done my maths right) which should be quick enough to not produce
pulses from the motor, and would growl rather than whine. For someone with
the necessary bits and a good workshop, this would be cheap to make.
<flame suit on>
Regards
[Technik] James
--- End Message ---
--- Begin Message ---
David C. Wilker wrote:
>> Instead of dissipative current control, can you use switching/chopper type
>> control?
From: James Massey
>It would be possible to make a motorised chopper, but you would still need
>to have freewheel diode/diodes. You would need to be a careful driver,
>since current limiting would be difficult to implement on a mechanical
>sustem (but not impossible) so would be in the hands (foot) of the driver.
If you are serious about this, research the kind of controls built after the
contactor controllers of the 1900's, but before the vacuum tube controllers
of the 1940's. The state of the art back then was the synchronous switch.
The key concept was that an LC resonant circuit was used to cause the
switch voltage or current natually fall to zero at the instant it needed to be
opened or closed. Arcing was thus minimized, so the switch could last for
billions of cycles. The "vibrator" found in 1940's car radios is an example
of this technology.
A PWM motor control had a mechanically resonant switch, such as a flat
spring with a contact on it. A pulse to a coil would flex the spring so the
contact closed, and then opened automatically a fixed time later (fixed
on-time). The motor inductance was resonated with a big capacitor at the
same frequency as the mechanical switch. Each time the switch closed,
the current ramped up from 0 to max, and then back down to almost zero
at the instant the switch opened. The controller controlled the duty cycle
by how often it triggered one of these fixe-on-time cycles.
This is exactly the same principle used in the SCR controllers, where the
SCR replaced the mechanical switch.
--- End Message ---
--- Begin Message ---
Hi all,
Does anyone have a schematic on a parallel/series battery arrangement for a
contactor controller?
Deeply interested in this as yes i agree its low cost and definately viable
for a small ev which i am interested in.
Cheers
On 26/10/06, jerryd <[EMAIL PROTECTED]> wrote:
HI GW and All,
----- Original Message Follows -----
From: GWMobile <[EMAIL PROTECTED]>
To: [email protected]
Cc: [EMAIL PROTECTED]
Subject: Re: Mechanical control, was: Re: EV controllers?
the 4th option...
Date: Wed, 25 Oct 2006 23:38:56 -0700
>Tell more about the contact controller.
>
>Please realize one of my goals is to keep it home built and
>simple.
>
>I want to stay away from things that require huge labs and
>factories like semiconductors.
I agree with you as I'm about to go to E
controllers for the first time, for the last 10 yrs I have
used only CC's.
They are made up of switches/contactors that
series/parallel the battery pack to different voltages, thus
vary the motors power output.
In low power EV's, you really only need/have 2
speeds, off and on except in parking lots, ect where you
need to go slow. Any speeds between that usually is just to
get to top speed. To vary speeds between these, you just
turn them on and off, depending on whether you need to go
faster or slower.
And since you need to limit the starting amps so
you don't break things, you use a starting resistor, easily
made from SS, other wire. For under 1500 lb EV's, get a golf
cart resistor series card and rewire them in parrallel is
about right, you can add, subtract to get the starting power
you want.
Field weakening, shorting the field some with say
a 12gge, 1' solid copper wire and a contactor, increases top
end power, speed and/or allows higher gearing.
A viable CC would then be 1 or 2 series/parallel
battery bank steps, a starting resistor and a field
weakening step or 2, giving 3 to 7 steps, is plenty smooth,
no different than a transmission shift when correctly sized.
And best, they have lots of power/amps naturally so
good starting torque for those times you need to start up a
hill, especially in EV's without transmissions, which would
need at least a 800 amp rating, price, to match it.
Citi-cars that replaced their CC's eith EC's were very
disappointed in their lack of power. Only when really high
amp EC's come around have they become viable in them except
in exceptionally flat places.
And the fact you can repair it yourself in a few
minutes by carrying a spare contactor or 2 and some
contacts, makes it a very good way to have an inexpensive,
reliable EV.
In my Ewoody, I was perfectly happy with just a
starting resistor and full power when it was at 45 mph and
36vdc. Resistor for starting, parking lots and on/off full
power at speeds above 10-20 mph. At 48 vdc and 60 mph, it
had too much power so needed another speed so went to
series/parallel the batts and field weakening to give me
field weakening speeds on 24 and 48 vdc and 48 vdc, for 3
more steps. If you have a lot of slow, stop and go driving,
pick the one with more S/P speeds.
Even if you have an EC, you should think about
putting in a parallel CC in case it fails, to get home. You
already have parts of it anyway to run the EC.
CC's have served well for 100+ yrs in commercial
use and a perfectly viable, some say better ;^D, controller
to use.
Jerry Dycus
>
>I believe that while not the most perfect , an electric car
>that could literally be made from a home builder including
>homebuilt batteries would have a whole new level of appeal
>even if it only did a 20 mile round trip.
>
>Ok maybe you have to buy the motor off ebay but everything
>else can perhaps be built or adapted from low tech
>components.
>
>By the way mit recently came out with a cheap solar heat
>powered electric generator using a solar concentrator,
>power sterring pumps running off solar heated freon and
>linked to a good old car generator to charge batteries.
>With great efficiencies and very low cost compared to solar
>cells why could that sit in an electric pickup truck and
>give great self rechargability?
>
>
>That's the kind of ultra low tech I want to aim for.
>
>
>
>On Wed, 25 Oct 2006 9:04 pm, Lee Hart wrote:
>>>> It'd work, just be exceptionally inefficient if you
>>>> tried to do it with a
>>>> series motor. Instead of having 80% of the battery
>>>> available energy turned into motion, you may be as bad
>>as 30%.
>> From: "Ted C."
>>> What's the problem with that? Millions of people every
>>> day drive cars powered by ICE motors every day. We
>>> don't hear to many of them complain about 30%
>>efficiency.
>> An ICE has a range of perhaps 300 miles even with its 30%
>> efficiency. If its engine was 100% efficient, its range
>> would be more like 1000 miles
>> on a tank of gas.
>>
>> An EV has a range of more like 30 miles, and that's
>> *with* an efficiency
>> of 80% or more. If its efficiency were 30%, its range
>> would be more like
>> 10 miles. That's unacceptable.
>>
>> I think what you're looking for is a contactor
>> controller. This is what they
>> used 100 years ago for EVs. They are crude and jerky, but
>> almost 100% efficienct and very simple. Basically, it is
>> a bunch of switches that wire
>> the batteries in various series/parallel combinations to
>> get the desired
>> motor speed.
>
>www.GlobalBoiling.com for daily updated facts about
>hurricanes, globalwarming and the melting poles.
>
>www.ElectricQuakes.com daily solar and earthquake data.
>
--- End Message ---
--- Begin Message ---
I wasn't going to post this due to the fear I would be laughed off the
list but what about this idea...
I thought of a uber simple high amp controller that is "out there"
Might be good for low budget drag racing.
Imagine a long 24 bar commutator that has big heavy bars on it and 2
adjustable 4 brush set riggings in which the brush width is the same as
the comm bar width. This is in the controller box. (problem1, where do I
get this commutator?)
This commutator is spun with a scooter motor (rpm = switching freq)
Power enters one set of brushes and leaves the other.
Pressing on the throttle cable advances the brush rigging allowing
overlap and the motor inductance integrates it. (Mechanical PWM overlap
= duty cycle)
The second set of adjustable riggings is moved away from the accelerator
by a shunt powered solenoid relative to the current being drawn-(current
limit!) Could even be adjustable since the solenoid operates against a
spring and we can adjust the spring tension by loosening the jam nut and
changing the spring preload.
Possible Names:
Mechanical PWM, Mechanical transistor, Sparky.
--- End Message ---
