EV Digest 6925
Topics covered in this issue include:
1) Re: DCDC converter and balancer in one? switch between 12V cells
by Marcin Ciosek <[EMAIL PROTECTED]>
2) Re: Cheap "balancer" for A123 pack
by Marcin Ciosek <[EMAIL PROTECTED]>
3) Re: Google presses for 100 MPG vehicle
by "Bob Rice" <[EMAIL PROTECTED]>
4) Re: Cheap "balancer" for A123 pack
by Tony Hwang <[EMAIL PROTECTED]>
5) Rolling Resistance
by "Rob Hogenmiller" <[EMAIL PROTECTED]>
6) RE: Cheap "balancer" for A123 pack
by "Dewey, Jody R ATC COMNAVAIRLANT, N422G5G" <[EMAIL PROTECTED]>
7) Motor cooling and temps
by "Richard Acuti" <[EMAIL PROTECTED]>
8) Re: Motor speed
by [EMAIL PROTECTED]
9) Re: Google presses for 100 MPG vehicle
by Lee Hart <[EMAIL PROTECTED]>
10) Re: Motor cooling and temps
by "Roland Wiench" <[EMAIL PROTECTED]>
11) Re: DCDC converter and balancer in one? switch between 12V cells
by Christopher Robison <[EMAIL PROTECTED]>
12) Re: DCDC converter and balancer in one? switch between 12V cells
by Lee Hart <[EMAIL PROTECTED]>
13) EVS meeting tonight - Toronto, Canada
by "james s" <[EMAIL PROTECTED]>
14) Re: Motor speed
by "TrotFox Greyfoot" <[EMAIL PROTECTED]>
15) Re: DCDC converter
by Lee Hart <[EMAIL PROTECTED]>
16) Siamese 8 Lives Again...Seattle here we come!
by John Wayland <[EMAIL PROTECTED]>
17) RE: Cheap
by Lee Hart <[EMAIL PROTECTED]>
18) RE: Motor speed
by "Bukosky, Allen" <[EMAIL PROTECTED]>
--- Begin Message ---
Tony,
good idea. Fortunately I had it way before and few working prototypes are
under testing right now :D
But anyway, good approach in controlling and you really will have your pack
balanced.
Marcin
On Thursday 21 June 2007 12:55:36 Tony Hwang wrote:
> I have an idea that I've been throwing around, would it be possible to make
> a DCDC converter for say a 300V pack that outputs 12V by switching between
> each of the 25 12V batteries in the 300V pack?
>
> It would probably need a capacitor to keep the voltage steady during the
> "switching", but it would stay on one 12V battery for say, 1 second, then
> very quickly switch to the next one. For batteries with lower voltages, it
> can stay on for say 0.5 seconds, while batteries with high voltages could
> be connected for 2 seconds.
>
> What sort of switches would be needed for something like this? I'm thinking
> something like a solid state relay? Ideally it would be something that
> physically cannot be connected to more than one battery at a time, so that
> you wouldn't have the risk of more than 12V out of this DCDC "converter".
>
> - Tony
--- End Message ---
--- Begin Message ---
Sure active balancing is the most required solution. But if you are not
willing to invest in controlling equipment you must stay with easiest
solution. For overcharging protection you can buy small electronics parts
that will cut of circuit if voltage will exceed 4.22 V and 2.8V. They are
really cheap.
Marcin
On Thursday 21 June 2007 14:39:45 Dewey, Jody R ATC COMNAVAIRLANT, N422G5G
wrote:
> Please educate me if I am wrong but I would think that if you want to
> balance your batteries you wouldn't want to drain some down to match the
> others but charge the low ones to match the others. Using shunt
> regulators will waste valuable charging current won't it? I think Lee
> Hart makes a battery balancer that takes the current and shunts it
> AROUND the battery but does not run it through a resistor.
>
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
> Behalf Of Marcin Ciosek
> Sent: Thursday, June 21, 2007 5:12
> To: ev@listproc.sjsu.edu
> Subject: Re: Cheap "balancer" for A123 pack
>
> Tony,
>
> recently I bough 1900 LiFP cells (not from A123 but it doesn't matter)
> and the voltage difference between highest and lowest value was 7mV !!
> Assuming you will start from similar point you balancer will do the
> trick as long as zener diodes won't differ too much (usually tolerance
> of of shunt voltage is 5%). That's my opinion. I would add a protection
> circuit preventing cells from deep discharge.
> If you don't need fancy BMS that would cost (for you configuration) 400E
> this will work fine.
>
> Marcin
--- End Message ---
--- Begin Message ---
----- Original Message -----
From: "Brian Pikkula" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Wednesday, June 20, 2007 12:43 PM
Subject: Re: Google presses for 100 MPG vehicle
The A/C in many parts of the country is not a luxury. I'm in Houston
and the heat index was 105ºF at 6pm yesterday and it's still June.
You sweat in the car even with the A/C on. That's why I am including
A/C into my Jetta conversion. Here, A/C is a necessity.
Brian
http://www.austinev.org/evalbum/960
Hi EVerybody;
Brian sure has a point. Rarely mentioned BUT if energy costs became more
than a common man could afford you would see a mass exodous of Sheeple OUT
of the South, Florida, So. Cal, Nm, Az etc when they become uninhabitable
for human life.I guess before AC there just wasn't many, if any, people in
these places?Here in the NE you can survive the cool winter by burning wood,
you can have all you want, IF you are willing to cut and haul it. Summers
are not that hot, except, maybe a few weaks of the summer. Nobody mentions
that the finate water supply, issues that are coming.
Few people remember the first VW's? They had little in creature
comforts, but sold faster than Volkswagenwerke could build them. Light,
economical, easy to fix, fun to drive. We need a E version of the old
Beetle!!Yes, you COULD have heat in a Electric!And(gasp) defrost, too!AC too
for less fortunate, geography wise folks? But ya don't need 3 tons of
vehicle to commute.
Well, chances are ya HAVE AC in the Jetta, I did, but it didn't work,
when I got the car, so I got rid of it early on. I have thought of painting
the roof of Jetta silver or white. Car is black, NOT MY choice of colors, I
like Silver best of all. Stay's clean, or at least LOOKS clean? So run the
AC off the drive motor or a separate motor.The power steering is nice in a
led sled, so I left it, running it, and the Rabbit vacuum pump, with a
common wrap-a-round v belt. Down side is no P/S when the motor isn't
turning. So ya slip the clutch when parking, like ya learned to do, when
learning to drive a standard? Rather than rip out the P/S rack and pinion I
just lived with the P/S system.
All this is the downside of conversions, Jerry or Lee aren't thinking of
a power brake and steering system.Freedom, at 1200lbs and Sunrise at 2lK
lbs only a tad hevier than an old Beetle.
Just a few thoughts
Bob
On 6/20/07, Richard Acuti <[EMAIL PROTECTED]> wrote:
These people need
power/heated seats, heated mirrors, A/C, power steering, power brakes,
GPS,
DVD player for the kids and on and on. You simply don't need this crap to
commute everyday.
--
No virus found in this incoming message.
Checked by AVG Free Edition. Version: 7.5.472 / Virus Database:
269.9.1/854 - Release Date: 6/19/2007 1:12 PM
--- End Message ---
--- Begin Message ---
Yes that would be better to move charge around instead of shunting, but there's
no way to make an active charge shuttling balancer for "cheap", at least not
that I know of.
- Tony
----- Original Message ----
From: "Dewey, Jody R ATC COMNAVAIRLANT, N422G5G" <[EMAIL PROTECTED]>
To: ev@listproc.sjsu.edu
Sent: Thursday, June 21, 2007 5:39:45 AM
Subject: RE: Cheap "balancer" for A123 pack
Please educate me if I am wrong but I would think that if you want to
balance your batteries you wouldn't want to drain some down to match the
others but charge the low ones to match the others. Using shunt
regulators will waste valuable charging current won't it? I think Lee
Hart makes a battery balancer that takes the current and shunts it
AROUND the battery but does not run it through a resistor.
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Marcin Ciosek
Sent: Thursday, June 21, 2007 5:12
To: ev@listproc.sjsu.edu
Subject: Re: Cheap "balancer" for A123 pack
Tony,
recently I bough 1900 LiFP cells (not from A123 but it doesn't matter)
and the voltage difference between highest and lowest value was 7mV !!
Assuming you will start from similar point you balancer will do the
trick as long as zener diodes won't differ too much (usually tolerance
of of shunt voltage is 5%). That's my opinion. I would add a protection
circuit preventing cells from deep discharge.
If you don't need fancy BMS that would cost (for you configuration) 400E
this will work fine.
Marcin
--- End Message ---
--- Begin Message ---
This morning I did a test for rolling resistance.
I was traveling at 60mph on flat ground in my car on a non windy day.
It took me 7 seconds to slow 0.1 Miles (on the odometer)
My speed at the distance of 0.1 Miles was 55mph at the 7second mark.
What would be my rolling resistance in this range 55-60mph?
God bless
--- End Message ---
--- Begin Message ---
The one that I am using is a battery tender. I have a 10 bank one. I
hook one up to each battery and it charges it all by itself. The unit
cost $450. The nice thing is I get individual equalization but I also
get individual monitoring. I used it yesterday to equalize my 24V
scooter. One battery came up to charge quickly, the other took 2 more
hours.
http://www.amazon.com/exec/obidos/tg/detail/-/B000GZMN18/sr=1-1/qid=1160
702654/ref=sr_1_1/102-8495456-3134502?_encoding=UTF8&m=A2Y992VSW47X5F&n=
&s=merchant&v=glance
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Tony Hwang
Sent: Thursday, June 21, 2007 9:20
To: ev@listproc.sjsu.edu
Subject: Re: Cheap "balancer" for A123 pack
Yes that would be better to move charge around instead of shunting, but
there's no way to make an active charge shuttling balancer for "cheap",
at least not that I know of.
- Tony
----- Original Message ----
From: "Dewey, Jody R ATC COMNAVAIRLANT, N422G5G" <[EMAIL PROTECTED]>
To: ev@listproc.sjsu.edu
Sent: Thursday, June 21, 2007 5:39:45 AM
Subject: RE: Cheap "balancer" for A123 pack
Please educate me if I am wrong but I would think that if you want to
balance your batteries you wouldn't want to drain some down to match the
others but charge the low ones to match the others. Using shunt
regulators will waste valuable charging current won't it? I think Lee
Hart makes a battery balancer that takes the current and shunts it
AROUND the battery but does not run it through a resistor.
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Marcin Ciosek
Sent: Thursday, June 21, 2007 5:12
To: ev@listproc.sjsu.edu
Subject: Re: Cheap "balancer" for A123 pack
Tony,
recently I bough 1900 LiFP cells (not from A123 but it doesn't matter)
and the voltage difference between highest and lowest value was 7mV !!
Assuming you will start from similar point you balancer will do the
trick as long as zener diodes won't differ too much (usually tolerance
of of shunt voltage is 5%). That's my opinion. I would add a protection
circuit preventing cells from deep discharge.
If you don't need fancy BMS that would cost (for you configuration) 400E
this will work fine.
Marcin
--- End Message ---
--- Begin Message ---
Well here's the good news:
I drove my car home 20 miles on the freeway at 55 & 65 mph. The moment I got
home, I slapped my multi-meter on the temp probe pigtails of my motor to see
if the probe was open or closed (since I haven't hooked up a dummy/warning
light yet) and the probe was still open. I assume this is good and that I
haven't overheated.
The motor is an ADC L91-4003 6.7" motor. I've seen motors that have a
coupling on the body where you can hook up a duct or a cooling blower. These
motors have no such fitting. This leaves me with more questions:
How can I set up forced air cooling for this motor?
Am I supposed to?
Do ADC motors provide some self cooling while they spin? For instance, if I
leave the car in gear while I coast, is the motor circulating air?
Should I just mount a couple of small DC fans to blow on the motor body?
Rich
_________________________________________________________________
PC Magazines 2007 editors choice for best Web mailaward-winning Windows
Live Hotmail.
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--- End Message ---
--- Begin Message ---
Think of a bicycle wheel.
If you measure it near the hub, 1 rpm of the bicycle wheel will still be 1
rpm if you measure it at the tube-valve-stem.
Its 1 trip around, that you're measuring and counting.
What you may be thinking of is distance traveled (the hub -sensor travels
less, while the valve stem distance traveled measures 2*Pi*R).
Think of it this way....
Imagine all the spokes are clean, and 1 spoke has a straw on it.
The portion of the straw near the center of the wheel travels less, but it
makes 1 revolution around the hub at the same time that the outer portion
(near the rim) of the straw.
A device measuring "revolutions" would be accurate either at the rim or at
the hub.
When Rob measures his rpm at the flywheel (whether or not its near the
rim), because its locked onto the motor shaft - (via taper lock, or some
other method) he receives the same rpm measurement there that he'd receive
if he used a magnet on the shaft itself.
Ed
"Rob Hogenmiller" <[EMAIL PROTECTED]>
Sent by: [EMAIL PROTECTED]
06/21/2007 09:06
Please respond to
ev@listproc.sjsu.edu
To
<ev@listproc.sjsu.edu>
cc
Subject
Re: Motor speed
How can that be?
If you measure the rpms at 3500 on a 1inch shaft motor.
And you now put a 2 inch shaft on the same motor still turning at the same
speed, the revolutions per minute will have changed because where your
measuring now takes it twice as to make one revolution.
So unless I'm incorrect it does make a difference where it's measured.
God bless
----- Original Message -----
From: "Phil Marino" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Thursday, June 21, 2007 7:10 AM
Subject: Re: Motor speed
>
> Rob - If I understand your question, you're asking - where in the motor
> should the RPM be 3500?
>
> The answer is - everywhere. RPM is short for revolutions per minute.
> Since the shaft/armature of the motor is a single rigid assembly, it
> doesn't matter where you measure it. All parts of it are rotating at
the
> same speed. ( rotational speed, not linear speed)
>
> Often RPM is measured at the motor shaft ( usually the non-drive end)
but
> some people measure it with a device which "sees" the fan blades go by.
> They will all give the same result. It's a matter of convenience of
> installation.
>
> I measure motor RPM with a hall-effect sensor that looks at a notch in
the
> flywheel. Since the flywheel is keyed to the motor shaft, it gives the
> right result. For me, that was a convenient way to do it.
>
> Phil Marino
>
>>From: "Rob Hogenmiller" <[EMAIL PROTECTED]>
>>Reply-To: ev@listproc.sjsu.edu
>>To: <ev@listproc.sjsu.edu>
>>Subject: Re: Motor speed
>>Date: Wed, 20 Jun 2007 22:57:16 -0500
>>
>>When you type 3500rpm for an electric motor, where is that determined
at?
>>
>>By/at the shaft circumference point, inside the motor, or some other
>>location?
>>
>>God bless
>>
>>
>>----- Original Message ----- From: "Mike Willmon" <[EMAIL PROTECTED]>
>>To: <ev@listproc.sjsu.edu>
>>Sent: Wednesday, June 20, 2007 10:21 PM
>>Subject: RE: Motor speed
>>
>>
>>>Storm,
>>>My WarP9 finds its sweet spot around 3500 RPM, which in 2nd gear
happens
>>>to be 35 mph. at 37mph I can feel acceleration start to
>>>taper and seems the perfect shift point to 3rd gear.
>>>
>>>Mike
>>>
>>>>-----Original Message-----
>>>>From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
>>>>Behalf Of Jim Husted
>>>>Sent: Wednesday, June 20, 2007 6:01 PM
>>>>To: ev@listproc.sjsu.edu
>>>>Subject: Re: Motor speed
>>>>
>>>>
>>>>Hey Storm
>>>>
>>>>Actually you don't want to lug the motor and you have
>>>>plenty of room and would say it'd be happier at the
>>>>3000 to 4000 rpms, you got lots more rpm to play with
>>>>8^)
>>>>
>>>>Hope this helps
>>>>Jim Husted
>>>>Hi-Torque Electric
>>>>
>>>>
>>>>--- Storm Connors <[EMAIL PROTECTED]> wrote:
>>>>
>>>> > I got the tachometer installed, now the big
>>>> > question.
>>>> > What is the best speed to aim for with my ADC 9"
>>>> > motor
>>>> > pushing almost 3500 pounds? I have been keeping it
>>>> > between 2000 and 2500 RPM generally. My thinking is
>>>> > that if the revs are too low under load, there is
>>>> > the potential of overheating. I have red lined it at
>>>> > 5000 so as not to break the motor.
>>>> >
>>>> > What do you think? I have been treating it like an
>>>> > ICE
>>>> > but don't know if that is right.
>>>> >
>>>> >
>>>>
>>>>
>>>>
>>>>
>>>>____________________________________________________________________________________
>>>>Never miss an email again!
>>>>Yahoo! Toolbar alerts you the instant new Mail arrives.
>>>>http://tools.search.yahoo.com/toolbar/features/mail/
>>>>
>>>>
>>>
>>>
>>
>
> _________________________________________________________________
> Make every IM count. Download Messenger and join the i'm Initiative now.
> It's free. http://im.live.com/messenger/im/home/?source=TAGHM_June07
>
>
--- End Message ---
--- Begin Message ---
From: "Brian Pikkula"
> The A/C in many parts of the country is not a luxury. Here, A/C
> is a necessity.
I think the real problem is to consider only the extremes; no A/C at all,
versus the refrigerator-on-wheels type of extreme A/C systems used in vehicles.
The A/C in a car is more powerful than the one for an apartment or small home!
That's what you get when energy is virtually free.
An EV forces us to realize that energy is *not* free! It has to come from
batteries, and they are expensive.
It would be nuts to try to air condition a home with single-pane windows, no
insulation in the walls, and lots of leaks and drafts. The size of the A/ would
be huge, and the cost to run it would be ruinous. But that's what we do in
cars.
If you're going to air condition your EV, it makes sense to re-think the
situation. Do you really want to use an inefficient automotive belt-driven A/C
system, with all its leaky rubber hoses and compromises to deal with the huge
variations in engine speed? Do you really want to try to cool a totally
uninsulated metal box, and bring it down 40 degrees F. below ambient air in
just a few minutes?
Or, are the less drastic ways to accomplish the same job? Use a smaller, more
efficient unit, like we use in our homes, that can run at a constant, efficient
speed from an inverter. Add insulation to the vehicle. Plug up holes and leaks
(often put there on purpose to vent fumes in case the ICE's exhaust system
leaked). Use tinted or even double-glazed windows. Use a timer to start the A/C
a little while before you return to drive the car, so it can be far smaller.
And of course, dress the the weather. Don't try to keep your car in the 60's
when it's 100+ deg.F outside. Use fans or "swamp coolers" to do more of the
work.
> All this is the downside of conversions, Jerry or Lee aren't
> thinking of a power brake and steering. Freedom, at 1200lbs
> and Sunrise at 2lK lbs are only a tad hevier than an old Beetle.
I'll certainly avoid them if it's feasible. We know how to design good braking
and steering systems that don't require power. But in so many modern cars,
designers just assume power steering and power brakes, and build them to make
it a necessity. Like A/C, if you start out assuming it is a necessity, then you
unconsciously warp the whole design to *make* it a necessity.
--
"Those who say it cannot be done should not interrupt the one who is
doing it." -- Chinese proverb
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377
--- End Message ---
--- Begin Message ---
Hello Richard,
If your brush cover is a solid steel cover, then cut a square hole in it and
mount a 12 volt Dayton 150 CFM or more blower on it. Cut a 1/8 inch thick
piece of rubber for a gasket. The outlet of these blowers had tabs that can
be bent to fit the shape of the curve of the motor. If not, than make a
adapter piece from a insulator board that you can pick up from a motor shop.
On my GE motor, it has a solid steel brush cover, and that is how it is
mounted. On my Warp 9 motor, it has a screen cover, so I made a steel fan
mount from a segment of 10 inch tubing. Welded on steel tabs that came down
on the front face of the motor and bolted it to two of the existing bolt
holes. Glue on a 1/8 inch rubber pad on this fan mount, so the steel does
not make direct contact with the aluminum screen.
I also mounted a 6 inch diameter air cleaner housing and filter unit that I
pick up from a auto parts store. I mounted a cross bar across the opening,
tap it for the 1/4 inch thread rod that is use to hold the air cleaner cover
on.
I use this type of fan blower for my Zilla which is mounted in a plastic
enclosure that has a outlet vent, and another one which is 120 VAC for my
PFC battery charger which brings in filter air for cooling.
Roland
----- Original Message -----
From: "Richard Acuti" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Thursday, June 21, 2007 7:49 AM
Subject: Motor cooling and temps
> Well here's the good news:
>
> I drove my car home 20 miles on the freeway at 55 & 65 mph. The moment I
> got
> home, I slapped my multi-meter on the temp probe pigtails of my motor to
> see
> if the probe was open or closed (since I haven't hooked up a dummy/warning
> light yet) and the probe was still open. I assume this is good and that I
> haven't overheated.
>
> The motor is an ADC L91-4003 6.7" motor. I've seen motors that have a
> coupling on the body where you can hook up a duct or a cooling blower.
> These
> motors have no such fitting. This leaves me with more questions:
>
> How can I set up forced air cooling for this motor?
> Am I supposed to?
> Do ADC motors provide some self cooling while they spin? For instance, if
> I
> leave the car in gear while I coast, is the motor circulating air?
> Should I just mount a couple of small DC fans to blow on the motor body?
>
> Rich
>
> _________________________________________________________________
> PC Magazine's 2007 editors' choice for best Web mail-award-winning Windows
> Live Hotmail.
> http://imagine-windowslive.com/hotmail/?locale=en-us&ocid=TXT_TAGHM_migration_HM_mini_pcmag_0507
>
>
--- End Message ---
--- Begin Message ---
On Thu, 2007-06-21 at 03:55 -0700, Tony Hwang wrote:
> I have an idea that I've been throwing around, would it be possible to make a
> DCDC converter for say a 300V pack that outputs 12V by switching between each
> of the 25 12V batteries in the 300V pack?
>
> It would probably need a capacitor to keep the voltage steady during the
> "switching", but it would stay on one 12V battery for say, 1 second, then
> very quickly switch to the next one. For batteries with lower voltages, it
> can stay on for say 0.5 seconds, while batteries with high voltages could be
> connected for 2 seconds.
I think this would work, but I see some problems.
1. What you want out of a DC/DC converter isn't really 12 volts. You
really want about 14V (see any of John Wayland's screeds about this
subject). All your vehicle accessories and lights were really designed
to run on approximately 14V, not 12.
2. You won't even get 12 volts out of this converter. You'll get a
variable voltage that starts out a little bit above 12, sags
significantly during acceleration, and rises significantly during
braking if you have regen. And over the course of your drive, your
headlights will start out somewhat dim, and will become *really* dim
(maybe illegally dim) by the end of your trip.
3. Not everyone uses 12V batteries. I've found that 8V batteries are
pretty popular, and of those using 6V, not everyone is using an even
number.
--
Christopher Robison
[EMAIL PROTECTED]
http://ohmbre.org <-- 1999 Isuzu Hombre + Z2K + Warp13!
--- End Message ---
--- Begin Message ---
Tony Hwang wrote:
> Would it be possible to make a DCDC converter for say a 300V pack
> that outputs 12V by switching between each of the 25 12V batteries
> in the 300V pack?
Yes, it would be possible. Take a look at my Battery Balancer for an example.
It's at:
http://www.geocities.com/sorefeets/balancerland/>>
It uses relays to select any 12v battery and route its wires to a single 12v
pair of wires. From there, you can measure its voltage, charge it, or discharge
it as desired.
I typically use the system to measure each battery's voltage, and then charge
it as needed with a small DC/DC converter powered from the pack as a whole, or
from the AC line when you're plugged in. It also maintains the 12v accessory
battery (it is no different than any other 12v battery in the pack).
What you're proposing is a bit simpler yet. I think you are suggesting
connecting each 12v propulsion battery in turn to the 12v accessory battery.
Done right, this could balance them all; i.e. push them all toward the same
state of charge.
Be aware that the peak currents that the switches have to carry are very high.
When two batteries are (say) 1 volt different and have (say) 0.005 ohms of
internal resistance, then the current that flows when the switches first close
is I = V/R = (13v-12v) / (0.005+0.005 ohms) = 100 amps! This would require big,
expensive switches to last for long.
It would be better to include some circuit to limit the peak current, so you
could use much smaller switches. It could be as simple as a resistor, though
this wastes a little energy (though a 1v drop out of 12v is still 92%
efficient).
A 12vin/12vout DC/DC converter could improve on this if done right.
Or, you could use a series inductor. Like a resistor, it limits the peak
current. When you first switch on, the current starts at zero and rises. The
inductance determines how fast it rises. It will eventually be at the same
current that you'd have due to the DC resistance of the inductor, which again
could be huge; however, the current between two batteries in parallel natually
falls pretty fast as they equalize at the same voltage. Plus, once your
switches have closed, they can handle a higher peak current, at least for a
short time.
> What sort of switches would be needed for something like this?
> I'm thinking something like a solid state relay?
You could use solid state switches, but I think you will find they are so
expensive and have so much voltage drop that they make the system impractical.
Things change pretty slowly in batteryland, so plain old mechanical relays
could be all you need.
> Ideally it would be something that physically cannot be connected
> to more than one battery at a time, so that you wouldn't have the
> risk of more than 12V out of this DCDC "converter".
Yes! This is the biggest problem I had with my Balancer. Little problems become
very big problems when they short a battery! I went to considerable lengths to
make it essentially impossible for two relays to close at once in my Balancer.
And if it still manages to happen somehow, there are fuses everywhere to
prevent disasters.
"The only thing new is the history you don't know yet." -- Harry Truman
--- End Message ---
--- Begin Message ---
This will be our last meeting untill after the summer.
When
Meetings of the Electric Vehicle Society are held on the third
Thursday of the month at 7:30 p.m. except for July and August
Where
Centennial College (Ashtonbee Campus), 75 Ashtonbee Rd, Room B216, Scarborough.
EVS
James Sullivan
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I think you're mistaking speed for RPM. The rim speed of a 1"
diameter shaft is indeed slower than the rim speed of a 2" diameter
shaft when they turn at the same RPM. In other words, if you have a
spinning shaft with a 1" section and a 2" section measuring the speed
of the surface of those two sections will give you different speeds.
This is the Angular Velocity of the surface of the shaft. However,
the entire shaft is spinning at the same RMP.
Trot, the mathematical, fox...
On 6/21/07, Rob Hogenmiller <[EMAIL PROTECTED]> wrote:
How can that be?
If you measure the rpms at 3500 on a 1inch shaft motor.
And you now put a 2 inch shaft on the same motor still turning at the same
speed, the revolutions per minute will have changed because where your
measuring now takes it twice as to make one revolution.
So unless I'm incorrect it does make a difference where it's measured.
God bless
--
| /\_/\ TrotFox \ Always remember,
| ( o o ) AKA Landon Solomon \ "There is a
| >\_/< [EMAIL PROTECTED] \ third alternative."
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--- Begin Message ---
From: [EMAIL PROTECTED]
> All isolated switchmode DC/DC converters run on DC and they all
> use a transformer.
True (except for a few oddballs, that use piezoelectrics or PV cells).
> Without the AC and without the transformer or inductor it would
> be an analog regulator which is horribly inefficient.
Usually true as well. But when the input-output voltage difference is small,
analog regulators are frequently used and can be more efficient than switching
regulators.
For example, the recent example of connecting a 12v accessory battery to a 12v
propulsion battery where there is less than a 1v difference between them. A
linear regulator is 92% efficient; this is hard to beat with a switchmode
converter.
> Generally, the higher the frequency the higher the efficiency.
> That is why the 60Hz line frequency is converted to DC so it can
> then be "switched" to a higher frequency.
No; frequency has very little effect on efficiency (assuming the parts are
properly designed for the frequencies involved). A 60 Hz transformer is just as
efficient as a 60 KHz transformer (both >95%). The main reason for higher
frequencies is to reduce size and cost (transformers cost by the pound).
--
I would not waste my life in friction when it could be turned into momentum. --
Frances Willard
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
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Hello to All,
Before getting into my post here, I want to publicly thank my friend Jim
Husted for his heroic effort in rebuilding & improving the Siamese 8
these past weeks! Jim is 'THE' DC motor king! His artistry is amazing. I
had the motor in the back of my work service truck yesterday in all its
purple glory, and the 'wows' it got from all those who had the pleasure
of seeing it, told it all. Thank you, Jim!
OK, here we go.....Advancing motor timing as you increase the volts to
the motor under high amperage has been long known for its benefits, so
it's nothing new. If Corbin had listened to all of us seasoned EVers,
the neutral timed ADC 8 inch motors would not have kept fireballing and
taking out controllers....all they had to do, was advance the timing 10
degrees. They and ADC refused to listen, motors kept fireballing, and DC
Power Systems faded away as the maker of fine air-cooled controllers
pretty much over losing their shorts 'doing the right thing' as they
covered all the controller failures in Corbin Sparrows. I helped more
than on Sparrow owner advance the timing in their unique cars, and
magically, all the problems went away as performance increased, too.
Loni wrote:
Are you manually adjusting the timing via a cable or the like? Seems
like the sort of thing I'd get tired of fiddling with, like choke
cables of yore.
Marko Mongillo's fun little Baby Blue Datsun minitruck has an ADC 9 inch
with a dash mounted pull-type cable that he uses to advance his motor
timing. Jim Husted built the timing system in that motor, and it works
wonderfully.
To do a motorized servo controlled timing advance on the Siamese 8 is a
bit difficult. The first problem, is how tightly the rear motor's shaft
output end (with a com setup) fits into the little Datsun's small
driveline tunnel entrance. It's so snug, there's no room for an external
lever-actuation system, with exception to perhaps the underside of the
rear motor section's com end. The front end of the Siamese 8, where
another com section is, is the opposite, in that you can't mount
anything under it, as it rests atop a mount that bolts to the transverse
frame rail, so any external lever-actuation system wound have to be
mounted on top of it or maybe on one side or the other. Now, not having
the exact place on both motor sections in which to mount these actuators
presents the first big obstacle because they can't easily be linked
together with a linkage shaft of some sort. The second one, is that on
the Siamese 8 motor, the timing rotation is opposite from one end to the
other, so any mechanical twisting setup has to move in two directions at
the same time, exactly the same way. You can see it's not an easy thing
to do with this unique hotrod electric motor. If anyone could come up
with a mechanical system to accomplish this, it's Father Time. Anyone
who's seen what mechanical marvels this guy can make with his hands,
knows what I'm talking about!
On the other hand, we've had pretty good success with the Siamese 8
without any sort of adjustable advance system. Consistent low 12's
bordering on the 11s aint all that bad. However, even with the new
stronger Genesis pack able to deliver lots of power, the pretty severe
arcy-sparky event in March and the 'wall' of 12.1 blocking us from the
11s, all point to the need for more motor advance. I decided to have Jim
to mods to give another 5 degrees of advance. This is a pretty big jump
in timing that will definitely have a noticeable effect. It 'should'
chase away the fireball monster while at the same time, give a
considerable hp boost at the higher rpms we run at the far end of the
track. It may take away some from the car's outrageous launch...maybe
not, but we'll soon find out as we are heading back to PIR next Friday,
June 29th, weather permitting. We had planned on going tomorrow but the
weather forecast changed from what was predicted to be mid 70's and
sunshine, to colder and wet. Calls were made and travel arrangements
changed for the Wall Street Journal guy as we now look to next weekend
to try for the 11s again.
I've been pretty focused the past couple of years in the way I've run
our racing strategy. I don't make multiple changes, and instead, try to
do one change at a time. We easily clicked off 12.1 second runs in March
until we had the motor problem, and the battery current was never turned
up higher than 1000 amps. It is tempting to crank up the battery pack
current next Friday, but I'll resist that and leave it set at 1000 amps.
The only difference will be the 15 degree timing advance, and of course,
the other performance mods to the motor that include a professionally
balanced armature stack, beefier brush interconnect arced solid bus bars
that replace the flex cables for better current carrying capacity (and
heat dissipation away from the brushes), and other nice 'Jim' tricks
applied....but the biggest change, is still the twist from 10 to 15
degrees in timing. In the event that the car does crack the 11s without
turning up the battery amps, it will then be my call whether or not to
turn it up to 1200 amps....we'll just have to see how it pans out, I
guess. I've got to keep in mind that the BIG EVent, the Wayland
Invitational III, is less than a month away, and we need to keep the
car running and in good shape for that.
The July races will be very exciting. Will Bill and his devoted team
become the first EVers to run in the 7s in the 1/4 mile? Will White
Zombie lightened from 2580 lbs. down to under 1900 lbs., fitted with
taller 3:70 gears, wheelie bars, and an A123 lithium pack outputting
1400+ amps, run low 11s - high 10s?
Tonight, after I return from yet another 320 mile round trip to Central
Oregon and back (7 trips in less than 4 weeks now), Tim Brehm and I will
meet up at my house at 6:00 pm or so to re-install the Siamese 8 in
White Zombie. Then, after a quick spin around the neighborhood and a
recharge to make sure all is well again, the car gets loaded up on the
trailer behind Tim's diesel Dodge. Tomorrow, Friday, I get to have a fun
85+ mpg run to Seattle in my Honda Insight with its hi pro sound system
while Tim will leave later in the early evening to bring the car up.
We've meet up with the SEVA gang early Saturday morning to be part of
the 2007 'Gasless on Greenwood' car show where 15,000 car fans will clog
Greenwood Avenue to see a huge array of hotrods and of course, electric
cars!
It's going to be fun!
See Ya....John Wayland
Plasma Boy Racing....'We blow things up, so you don't have to!'
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--- Begin Message ---
From: "Dewey, Jody R ATC COMNAVAIRLANT, N422G5G"
> Please educate me if I am wrong but I would think that if you want
> to balance your batteries you wouldn't want to drain some down to
> match the others but charge the low ones to match the others.
Any method that lets you put *different* amounts of charge in each battery or
cell can work for balancing.
Think of it like this. You have a bunch of 1-gallon jugs to fill. In theory
they all hold 1 gallon, but you find they actually vary from 0.9 to 1.1 gallon
Charging batteries in series automatically puts exactly the same current for
the same time into all batteries. This is like putting exactly 1 gallon in
every jug. This will cause some to be slightly less than full; and other to be
OVERfilled, with water drizzling down the side.
In both cases, you've shortened the battery's life. The over-filled ones are
harmed right now, from overcharging. The under-filled ones ae harmed later,
when you drive thinking you can get 1 gallon from each and it runs empty at 0.9
gallons.
So, what do you do to insure that every jug has the same amount of water?
1. You can fill them individually with a pump with an automatic
shutoff. This is what is done with modular chargers (one charger
per battery).
2. You can add a drain hose to each battery at the 0.9 gallon level.
When it reaches this level, excess liquid is routed safely to a
drain. This is what shunt regulators like the Rudman regulators
do; they bypass excess charging current, and dispose of it as heat
somewhere.
3. You can put 0.9 gallons into all of them, and then use a separate
filling hose to top off each one individually. This is what an
additive system does.
4. You can fill them all at once, with the same amount going to
each jug, but have a set of siphon hoses between jugs to transfer
liquid from the more-full ones to the less-full ones. This is
what charge transfer systems do, like the Powercheq or my Battery
Balancer does.
They all work; they just have different strengths and weaknesses.
--
I would not waste my life in friction when it could be turned into momentum. --
Frances Willard
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
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Hi Rob,
The circumference of a 2 inch shaft has twice as far to go to make one
revolution, but it is moving twice as fast as the circumference of a 1
inch shaft. Thus, the time it takes to make one revolution is the same
for a 1 inch and for a 2 inch shaft.
Think about putting a mark on the end of the shaft from the center to
the circumference. If every point on the mark didn't take the same time
to make one revolution, then the mark would "twist" around the shaft as
it rotated. Obviously, this doesn't happen.
The same will be true for any point on the motor's armature assembly, so
it doesn't make any difference where on the armature assembly you take
an RPM measurement. A speed or velocity measurement would be dependent
on diameter, but that isn't what RPM is about.
Allen
-----Original Message-----
From: Rob Hogenmiller [mailto:[EMAIL PROTECTED]
Sent: Thursday, June 21, 2007 8:07 AM
To: ev@listproc.sjsu.edu
Subject: Re: Motor speed
How can that be?
If you measure the rpms at 3500 on a 1inch shaft motor.
And you now put a 2 inch shaft on the same motor still turning at the
same
speed, the revolutions per minute will have changed because where your
measuring now takes it twice as to make one revolution.
So unless I'm incorrect it does make a difference where it's measured.
God bless
----- Original Message -----
From: "Phil Marino" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Thursday, June 21, 2007 7:10 AM
Subject: Re: Motor speed
>
> Rob - If I understand your question, you're asking - where in the
motor
> should the RPM be 3500?
>
> The answer is - everywhere. RPM is short for revolutions per minute.
> Since the shaft/armature of the motor is a single rigid assembly, it
> doesn't matter where you measure it. All parts of it are rotating at
the
> same speed. ( rotational speed, not linear speed)
>
> Often RPM is measured at the motor shaft ( usually the non-drive end)
but
> some people measure it with a device which "sees" the fan blades go
by.
> They will all give the same result. It's a matter of convenience of
> installation.
>
> I measure motor RPM with a hall-effect sensor that looks at a notch in
the
> flywheel. Since the flywheel is keyed to the motor shaft, it gives
the
> right result. For me, that was a convenient way to do it.
>
> Phil Marino
>
>>From: "Rob Hogenmiller" <[EMAIL PROTECTED]>
>>Reply-To: ev@listproc.sjsu.edu
>>To: <ev@listproc.sjsu.edu>
>>Subject: Re: Motor speed
>>Date: Wed, 20 Jun 2007 22:57:16 -0500
>>
>>When you type 3500rpm for an electric motor, where is that determined
at?
>>
>>By/at the shaft circumference point, inside the motor, or some other
>>location?
>>
>>God bless
>>
>>
>>----- Original Message ----- From: "Mike Willmon"
<[EMAIL PROTECTED]>
>>To: <ev@listproc.sjsu.edu>
>>Sent: Wednesday, June 20, 2007 10:21 PM
>>Subject: RE: Motor speed
>>
>>
>>>Storm,
>>>My WarP9 finds its sweet spot around 3500 RPM, which in 2nd gear
happens
>>>to be 35 mph. at 37mph I can feel acceleration start to
>>>taper and seems the perfect shift point to 3rd gear.
>>>
>>>Mike
>>>
>>>>-----Original Message-----
>>>>From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]
>>>>Behalf Of Jim Husted
>>>>Sent: Wednesday, June 20, 2007 6:01 PM
>>>>To: ev@listproc.sjsu.edu
>>>>Subject: Re: Motor speed
>>>>
>>>>
>>>>Hey Storm
>>>>
>>>>Actually you don't want to lug the motor and you have
>>>>plenty of room and would say it'd be happier at the
>>>>3000 to 4000 rpms, you got lots more rpm to play with
>>>>8^)
>>>>
>>>>Hope this helps
>>>>Jim Husted
>>>>Hi-Torque Electric
>>>>
>>>>
>>>>--- Storm Connors <[EMAIL PROTECTED]> wrote:
>>>>
>>>> > I got the tachometer installed, now the big
>>>> > question.
>>>> > What is the best speed to aim for with my ADC 9"
>>>> > motor
>>>> > pushing almost 3500 pounds? I have been keeping it
>>>> > between 2000 and 2500 RPM generally. My thinking is
>>>> > that if the revs are too low under load, there is
>>>> > the potential of overheating. I have red lined it at
>>>> > 5000 so as not to break the motor.
>>>> >
>>>> > What do you think? I have been treating it like an
>>>> > ICE
>>>> > but don't know if that is right.
>>>> >
>>>> >
>>>>
>>>>
>>>>
>>>>
>>>>____________________________________________________________________
________________
>>>>Never miss an email again!
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>>>>
>>>
>>>
>>
>
> _________________________________________________________________
> Make every IM count. Download Messenger and join the i'm Initiative
now.
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>
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