EV Digest 6415
Topics covered in this issue include:
1) Re: Brake Pressure Multiplier -brake drag
by Nick <[EMAIL PROTECTED]>
2) Re: what does unsprung mass or weight mean?
by "[EMAIL PROTECTED]" <[EMAIL PROTECTED]>
3) RE: what does unsprung mass or weight mean?
by Don Cameron <[EMAIL PROTECTED]>
4) Re: what does unsprung mass or weight mean?
by "Peter VanDerWal" <[EMAIL PROTECTED]>
5) Re: Soneil Chargers
by Lee Hart <[EMAIL PROTECTED]>
6) Re: Brake Pressure Multiplier?
by Lee Hart <[EMAIL PROTECTED]>
7) Re: Brake Pressure Multiplier?
by Lee Hart <[EMAIL PROTECTED]>
8) Re: Brake Pressure Multiplier?
by Lee Hart <[EMAIL PROTECTED]>
9) Re: Brake Pressure Multiplier?
by Lee Hart <[EMAIL PROTECTED]>
10) Re: Brake Pressure Multiplier?
by Lee Hart <[EMAIL PROTECTED]>
11) Re: Brake Pressure Multiplier?
by Nick <[EMAIL PROTECTED]>
12) Re: what does unsprung mass or weight mean?
by "Phil Marino" <[EMAIL PROTECTED]>
13) Drumming For Brakes. WAS Re: Brake Pressure Multiplier?
by "Bob Rice" <[EMAIL PROTECTED]>
14) Re: Brake Pressure Multiplier?
by "Phil Marino" <[EMAIL PROTECTED]>
15) Re: Brake Pressure Multiplier?
by Frank John <[EMAIL PROTECTED]>
16) Re: Brake Pressure Multiplier?
by "Peter Gabrielsson" <[EMAIL PROTECTED]>
17) RE: Cost to drive a EV
by "David Roden" <[EMAIL PROTECTED]>
18) RE: Cost to drive a EV
by "Dewey, Jody R ATC COMNAVAIRLANT, N422G5G" <[EMAIL PROTECTED]>
19) Citi car's Brakes, or lack thereoff WAS
by "Bob Rice" <[EMAIL PROTECTED]>
20) RE: Brake Pressure Multiplier?
by "Roger Stockton" <[EMAIL PROTECTED]>
21) Re: what does unsprung mass or weight mean?
by "Kaido Kert" <[EMAIL PROTECTED]>
22) Re: what does unsprung mass or weight mean?
by "[EMAIL PROTECTED]" <[EMAIL PROTECTED]>
23) Re: Loud Hybrid Legislation (was: Re: Chain Noise Re: Personal
Electric Transport)
by "Michael" <[EMAIL PROTECTED]>
24) Any suggestions for electric heater cores for pack voltages over
300vdc?
by Paul Wallace <[EMAIL PROTECTED]>
25) Re: Any suggestions for electric heater cores for pack voltages over
300vdc?
by MIKE WILLMON <[EMAIL PROTECTED]>
--- Begin Message ---
I'll second everything Phil has said. The Volvo 240 series brakes are
exactly like the ones Phil described on the 140, and I doubt that the
drag on any of these brakes could be measured with a torque wrench. In
fact, with the tire off the ground, I can give it a good heave and it
will spin several times before stopping.
Phil Marino wrote:
The Volve 140 series actually had four pistons in each front caliper (
and two in each rear caliper). They also had small drum brakes in the
rear ( as well as the main service disks) that were used only for
parking brakes.
The redundant hydraulic systems were set up so that any hydraulic
failure would still leave you with working brakes on both front wheels
and one rear wheel.
As far as brake drag, have people measured this, and is it really a
significant source of drag?
It seems to me ( I haven't done any measurements, but I will when the
temperature here goes positive again) that, whenever I spin an unloaded
wheel - when changing tires, for example- there is not a lot of drag.
I suspect that the torque due to brake drag would be too low to measure
with a torque wrench ( at least, the ones I have).
Phil
From: Nick <[EMAIL PROTECTED]>
Reply-To: ev@listproc.sjsu.edu
To: ev@listproc.sjsu.edu
Subject: Re: Brake Pressure Multiplier?
Date: Tue, 13 Feb 2007 22:19:26 -0800
I have only worked on these kinds of calipers on the Volvo 240 series,
but I have seen them on some sports cars, like Porsches and Corvettes.
The Volvo calipers are made by ATE and Girling (depending on front or
rear axle and model year). I have been driving vehicles with
four-wheel disc brakes for years, and others with drum brakes, and I
would much prefer disc brakes over drum.
Lee Hart wrote:
From: Nick
I know many cars - Volvos come to mind - have multiple pistons in
each caliper. In these set-ups the caliper is fixed and each pad has
one or more pistons to put pressure on it. I would think that by
eliminating the sliding caliper, that would eliminate the
possibility of those surfaces seizing, and the multiple pistons with
a rubber o-ring on each might retract more overall than a single
o-ring for the entire caliper. I know the added complexity of these
systems can lead to other problems, but like anything mechanical,
maintenance is critical.
The Volvo is the one car I've heard of that does this. Are there
others? Does anyone know if the Volvo system does in fact reduce
dragging brakes?
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Hi all,
On a truck, if you had extra weight in the drivetrain
(wheels, tires, driveline, pistons, crankshaft, gears,
pulleys, fanbelts), it would be "unsprung weight".
But, if you simply carried the weight as a load ON the
truck, it is "sprung weight".
Similarly, on a person, If you tied a brick to your
ankle, it would be "unsprung weight".
But, if you tied the brick to your back, it would be
"sprung" weight.
As an interesting experiment, try running across the
street with the brick strapped to your back (versus
your ankle) to experience the difference.
It'll be easy to see the different effects and
requirements of energy!
Hope this helps.
Jay Lashlee, GoWheel.com
[EMAIL PROTECTED]
____________________________________________________________________________________
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--- Begin Message ---
Unsprung weight is the amount of weight that is not supported by the
suspension of the vehicle. This typically includes the tire, wheel, brakes,
part of the drive axle, part of the shock, etc. The lighter the unsprung
weight the more the suspension can react to bumps in the road thus keeping
the tire on the ground more often. If you look at race cars, the designers
work hard to maximize the amount of tire on the ground - one of the tricks
is to keep unsprung weight low. There of course are huge compromises - one
is using large tires (heavy), but they have more tire contact patch (good)
The problem with hub motors is that it adds weight to the unsprung weight.
The more weight, the more it cannot react quickly to bumps in the road. In
a performance sports car (one that likes to go around corners fast) this can
cause the wheel to skip or hop. This can cause the car to slide.
Don Cameron, Victoria, BC, Canada
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-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Jonathan Perret
Sent: February 14, 2007 7:47 AM
To: ev@listproc.sjsu.edu
Subject: what does unsprung mass or weight mean?
Hi,
I have a basic mechanical question:
in discussions about direct drive electric motors it's often mentioned that
one of the design problems (or drawbacks) to this approach is that the motor
(presents) an unsprung mass (or weight) (to the wheel?)
can someone explain what this refers to / what it means and potential
work-arounds / solutions?
I'm interested in pursuing front wheel direct drive
I asked a friend of mine who is a mechanical engineer (and BTW a self-styled
genius) and he wasn't familiar with the term.
thanks,
Jonathan
--- End Message ---
--- Begin Message ---
> On a truck, if you had extra weight in the drivetrain
> (wheels, tires, driveline, pistons, crankshaft, gears,
> pulleys, fanbelts), it would be "unsprung weight".
Umm, no. Only the weight that is out by the wheels and moves with the
wheels in "unsprung". I.e. the Wheels and tires part, but NOT the
pistons, crankshaft, gears, pulleys, and fanbelts. All of the later parts
are "sprung" since they are fixed to the body and carried by the
suspension.
--
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--- Begin Message ---
Lee Hart wrote:
> What does it show for KWH (kilowatt hours used), accumulated over
> (say) 24 hours? This should capture the total amount of energy being
> put into a fully charged pack.
Darryl McMahon wrote:
Sorry, Lee. I don't have that information off-hand. The Porsche is
currently stored for the winter, and awaiting a new controller in the
spring. I could do a test on the bicycle battery pack if that would
be of any value.
That would work, too. Any 12v battery should work. It would give you an
idea just how much current on average is going into a fully charged battery.
I would connect the charger to a big filter capacitor, to simulate a
"perfect" battery with almost no self-discharge (compared to a battery).
See how many watthours per day the charger uses. Then connect a battery,
and see how many watthours per day it uses. The difference between the
two is watthours going into the battery. Doing it this way gets rid of
the measurement errors in the Kill-A-Watt and the charger's efficiency.
--
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in -- Leonard Cohen
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
--- End Message ---
--- Begin Message ---
David Roden wrote:
For some reason, I'm thinking of the Citicar - it started out with
aircraft disc brakes in front, but gave them up in favor of drums
all round.
The early CitiCars must have had the worst brakes ever used in a
"production" automobile. They went *way* too far in the direction of
cheap and light. I think the first ones were Dico aircraft brakes; they
only need to stop you *once*, and only need to work for forward. Then
they went to tiny little trailer brakes with stamped drums, that warped
badly. The later ComutaCar and ComutaVan went to larger 7" trailer
brakes, but still had the stamped drums. I replaced the drums with cast
iron ones on my ComutaVan, and the brakes finally worked reasonably well.
--
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in -- Leonard Cohen
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
--- End Message ---
--- Begin Message ---
Nick wrote:
I have only worked on these kinds of calipers on the Volvo 240 series,
but I have seen them on some sports cars, like Porsches and Corvettes.
The Volvo calipers are made by ATE and Girling (depending on front or
rear axle and model year). I have been driving vehicles with four-wheel
disc brakes for years, and others with drum brakes, and I would much
prefer disc brakes over drum.
Nick, do you know if the Volvo double-acting brakes drag? Or, do they
have the same sorts of problems as the more common single-acting disk
brakes?
--
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in -- Leonard Cohen
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
--- End Message ---
--- Begin Message ---
Frank John wrote:
Lee: what is estimated final weight?
The Solectria version must have been around 1200 lbs without batteries.
We're not likely to do this well, at least at first, so 1400 lbs is a
good guess. But the chassis is built to carry its own weight in
batteries, which makes the curb weight around 2800 lbs.
The only "real" way to tell is to build one and test, then compare
to similar offerings. If 60-0 performance is poor then it'd be hard
to justify.
Justify what? Disk or drum brakes?
Solectria had a 50kw drive system. We're using a WarP 9" and Zilla
controller, which is >100kw. This should be as good or better than the
average car.
--
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in -- Leonard Cohen
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
--- End Message ---
--- Begin Message ---
Peter Gabrielsson wrote:
The EV1 had a electro hydraulic disc brakes in addition to regen, the
brakes were indeed designed not to drag. Some info can be gleamed from
this PDF
http://www.thejaffes.org/rory/ev1/ev1.pdf
Interesting, but this is more sales literature than technical data. Do
you know what was actually different about the EV1 front brakes to
insure that they didn't drag?
--
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in -- Leonard Cohen
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
--- End Message ---
--- Begin Message ---
Jeff Shanab wrote:
ironically BMW is advertising that their disk brakes drag with just the
right amount when wet weather is detected so that they are dry and
available for max braking when needed. Although this is a good thing,
This advertisement can be miss-interpreted.
I have an old cartoon with two pictures. The first is a cockroach,
titled "a bug". The second is the same cockroach, but dressed up in a
suit and tie, titled "a feature".
Often, a company will take some negative characteristic (like dragging
brakes), and find some way to describe it as a feature (cleans and dries
your rotors).
--
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in -- Leonard Cohen
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
--- End Message ---
--- Begin Message ---
I don't have any hard data to say one way or the other. I might be able
to get a rough idea by comparing them to the single-acting calipers on
my S-10 since the brakes, tires and hubs are similar in size and both
use the same type of bearings, but I'm not sure how to measure it.
Lee Hart wrote:
Nick wrote:
I have only worked on these kinds of calipers on the Volvo 240 series,
but I have seen them on some sports cars, like Porsches and Corvettes.
The Volvo calipers are made by ATE and Girling (depending on front or
rear axle and model year). I have been driving vehicles with
four-wheel disc brakes for years, and others with drum brakes, and I
would much prefer disc brakes over drum.
Nick, do you know if the Volvo double-acting brakes drag? Or, do they
have the same sorts of problems as the more common single-acting disk
brakes?
--- End Message ---
--- Begin Message ---
From: "[EMAIL PROTECTED]" <[EMAIL PROTECTED]>
Reply-To: ev@listproc.sjsu.edu
To: ev@listproc.sjsu.edu
Subject: Re: what does unsprung mass or weight mean?
Date: Wed, 14 Feb 2007 08:47:15 -0800 (PST)
Hi all,
On a truck, if you had extra weight in the drivetrain
(wheels, tires, driveline, pistons, crankshaft, gears,
pulleys, fanbelts), it would be "unsprung weight".
But, if you simply carried the weight as a load ON the
truck, it is "sprung weight".
Similarly, on a person, If you tied a brick to your
ankle, it would be "unsprung weight".
But, if you tied the brick to your back, it would be
"sprung" weight.
As an interesting experiment, try running across the
street with the brick strapped to your back (versus
your ankle) to experience the difference.
It'll be easy to see the different effects and
requirements of energy!
I don't think this is a valid comparison. With a brick strapped to your
ankle, you have to repeatedly accelerate and decelerate the extra mass as
you travel forward. On a wheeled vehicle, the unsprung mass moves at
constant speed as you travel forward.
The energy loss effects of unsprung mass on a car - compared to a brick on
your ankle- are much more subtle, and depend largely on the smoothness of
the road surface.
Phil
Hope this helps.
Jay Lashlee, GoWheel.com
[EMAIL PROTECTED]
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--- Begin Message ---
----- Original Message -----
From: "Rich Long" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Wednesday, February 14, 2007 6:12 AM
Subject: Re: Brake Pressure Multiplier?
> On Tue, 2007-02-13 at 20:31 -0800, Lee Hart wrote:
>
> > How would people feel if I used drum brakes on the Sunrise kit car?
> >
> > 1. Great idea! Eliminates dragging brakes, and probably cheaper too.
> >
> > 2. Horrible idea! No one would even consider not having disk brakes
nowdays.
> >
>
>
> I'd like to assemble one of your kits and I vote #1.
>
> Yeah! Me too. Funny the Corvair Corsa, of 1965 had 10 inch druns all
around, and did fine. NO power assist, but with those hugh drums you
wouldn't have needed it. Sunrise isn't/ won't be a racing car, at least in
early format. For Mom to haul the kids, andor Dad to drive to work, it'll be
good enough.IF you wanna go auto Crossing or run Pike's Peak, do yur disc's
all around and 11" motor.
Bob
>
> --
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>
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--- Begin Message ---
From: "Michael Perry" <[EMAIL PROTECTED]>
Reply-To: ev@listproc.sjsu.edu
To: <ev@listproc.sjsu.edu>
Subject: Re: Brake Pressure Multiplier?
Date: Mon, 19 Jan 2026 21:34:54 -0800
The claims of this manufacturer... with their "stepped" cylinders sounds
like perpetual motion, as applied to brakes.
Not necessarily. It's still not clear to me exactly how their system works.
.
If it is a multi-ratio system ( as I first interpreted it, and, as Jeff
Shanab also interpreted it ) it could provide fast, low-force motion at the
first stage of actuation, and slower, higher force action toward the end of
it's range ( where you need the higher force, but not much motion.)
That would not be perpetual motion - just good engineering. Even if that is
not what they have done, that type of system is possible and would
certainly reduce ( or eliminate) the need for power assist on disc brake
systems.
Phil
Peter: You are correct. With drum brakes, you have a secondary leverage
applied. In most systems, you have a single wheel cylinder, applying force
outwards at one end of the shoes, the other end fixed. For a given diameter
of wheel cylinder, the force is multiplied. Unfortunately, there is also
more slack to take up, even when the self-adjusters keep the shoes
adjusted.
(eg: partially pull the emergency brake... less pedal distance.)
Disks don't clear the rotors by as great a distance. Though the force is
not
leveraged, you'll note that most calipers are of a larger diameter, giving
a
similar leverage (all hydraulic) and similar stopping power, when not power
assisted. Where power assist comes into play is in allowing a smaller
caliper to be used. This keeps your pedal pressure low (toe operated) and
travel distance is minimized by keeping the caliper smaller... less fluid
to
move the cylinder the same distance. A longer stroke (more volume) master
cylinder and larger calipers would have the same effect... except now your
pedal distance would be further. Instead of just heel/toeing the pedal,
you'd need to lift your foot and press further. Same effect, though... and
given enough leverage advantage, similar pedal pressure.
The only real advantage to using multiple calipers is that the calipers can
be smaller and spaced across the pad.
Now you get the advantage of more
piston area and the pressure is applied over the width of the pad... ala
some MC designs. The leverage is the same per square inch of piston,
however.
When ya'll buy special stepped cylinders, might I also suggest "multi fire"
spark plugs... guaranteed to increase your MPG and performance by 20%???
<vbg>
----- Original Message -----
From: "Peter VanDerWal" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Monday, February 12, 2007 5:50 PM
Subject: Re: Brake Pressure Multiplier?
> Hmm, interesting.
>
> Still, someone correct me if I'm wrong. but it seems to me that untill
you
> experience brake fade, drum brakes will like provide more stopping power
> per pedal effort on un-assisted brakes (due to the self-actuating
> feature).
>
> I pretty sure that sports cars went to disc brakes (even un-assisted
disc
> brakes) because racing involves LOTS of slowing down and speeding up.
> The kind of driving that is NOT typical for most EV commuters. I'm
> thinking that drum brakes might actually be better than discs in a
> commuter type EV.
>
> >>Were you experiencing brake fade due to long down hills or frequent
stops
> >>from high speed?
> >>
> >>THe big advantage of disc brakes is that they can shed heat faster and
> >>avoid fading (to some extent).
> >
> > That certainly is one advantage, but it's a little more complicated
than
> > that.
> >
> > Drum brakes are generally " self-actuating" by design, That is, most
of
> > the
> > force that pushes the shoes against the inside of the drums is caused
by
> > the
> > friction force of the drums on the shoes. Only a relatively small
> > actuation
> > force is required to start this chain reaction. That is why drum
brake
> > systems can easily get away without power assist.
> > Think of it as being similar to a rope brake that you can make by
wrapping
> > a
> > rope several times around a tree. You only need a small force on one
end
> > to
> > control a very large tension force at the other end.
> >
> > The downside of this self-actuating system is that the final braking
> > torque
> > is not linear with the coefficient of friction between the shoes and
drum.
> > It's a much stronger function of the friction coefficient So, a
small
> > drop
> > in friction coefficient ( due to temperature rise, for example)
> > can reduce the stopping force drastically. This is what used to be
called
> > "brake fade".
> >
> > With disc brakes, the stopping torque is linearly proportional to the
> > friction coefficient. A small ( or moderate) change in that
coefficient
> > doesn't have nearly as strong an effect on the stopping power.
> >
> > Phil
> >
> > _________________________________________________________________
> > Search for grocery stores. Find gratitude. Turn a simple search into
> > something more.
> >
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> >
> >
>
>
> --
> 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.
>
_________________________________________________________________
From predictions to trailers, check out the MSN Entertainment Guide to the
Academy Awards®
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--- End Message ---
--- Begin Message ---
Lee, I meant to justify the use of drum brakes. My personal preference would
be discs. If braking performance is unacceptable and might be improved with
use of discs, than it'd obviously be harder to justify the use of drums.
I wonder how much effect weight distribution would have on performance? Ex. no
need for rear discs on the majority of cars as weight transfer under heavy
braking makes the front brakes do most of the work. If battery weight is
mostly carried by the rear wheels front discs may be unnecessary.
BTW, kudos for this project! I wish I knew more about it.
----- Original Message ----
From: Lee Hart <[EMAIL PROTECTED]>
To: ev@listproc.sjsu.edu
Sent: Wednesday, February 14, 2007 12:03:17 PM
Subject: Re: Brake Pressure Multiplier?
Frank John wrote:
> Lee: what is estimated final weight?
The Solectria version must have been around 1200 lbs without batteries.
We're not likely to do this well, at least at first, so 1400 lbs is a
good guess. But the chassis is built to carry its own weight in
batteries, which makes the curb weight around 2800 lbs.
> The only "real" way to tell is to build one and test, then compare
> to similar offerings. If 60-0 performance is poor then it'd be hard
> to justify.
Justify what? Disk or drum brakes?
Solectria had a 50kw drive system. We're using a WarP 9" and Zilla
controller, which is >100kw. This should be as good or better than the
average car.
--
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in -- Leonard Cohen
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
____________________________________________________________________________________
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--- End Message ---
--- Begin Message ---
I don't recall at this time, I talked to one of the mechanical
engineers about a year ago and he mentioned that one of the reason for
the electric hydraulic brake system was to eliminate drag. I'll ask
him about it again next time I see him.
On 2/14/07, Lee Hart <[EMAIL PROTECTED]> wrote:
Peter Gabrielsson wrote:
> The EV1 had a electro hydraulic disc brakes in addition to regen, the
> brakes were indeed designed not to drag. Some info can be gleamed from
> this PDF
> http://www.thejaffes.org/rory/ev1/ev1.pdf
Interesting, but this is more sales literature than technical data. Do
you know what was actually different about the EV1 front brakes to
insure that they didn't drag?
--
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in -- Leonard Cohen
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
--
www.electric-lemon.com
--- End Message ---
--- Begin Message ---
On 14 Feb 2007 at 8:41, Dewey, Jody R ATC COMNAVAIRLANT, N422G5G wrote:
> I would really recommend separating the buddy pairs
> into strings of series batteries that can be connected in parallel
> during use or charging.
As I said in my earlier message - which you even included below yours! - a
few years back, I had a problem even with paralleled >strings<.
One battery in one string developed a shorted cell. The good string would
run itself flat trying to charge the bad battery - and I suppose also
overcharging the others in the bad battery's string.
The batteries survived the experience, but I'm quite sure they lost some
cycle life.
The trouble is that such a situation can easily go unnoticed, unless some
catastrophic event occurs. What alerted me was the reduced capacity - I
guess the good string was supplying all the energy. If I hadn't noticed
that, and had continued to use them as they were, I probably would have
ruined all the batteries in short order.
That said, I use a 36v series-parallel lashup in my Elec-Trak - 3 sets of
paralleled modules in series ("buddy pairs") - and it's worked well for
about 7 years. I think that's mostly dumb luck. To do series-parallel
right, I think you really should have some way of monitoring the strings
and/or modules separately.
David Roden - Akron, Ohio, USA
EV List Administrator
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--- Begin Message ---
The Link 20 supposedly is capable of monitoring two strings - I think it
is limited in how much voltage it can handle though. Maybe each string
should have its own current shunt and voltage gage so as to monitor them
separately.
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of David Roden
Sent: Wednesday, February 14, 2007 13:30
To: ev@listproc.sjsu.edu
Subject: RE: Cost to drive a EV
On 14 Feb 2007 at 8:41, Dewey, Jody R ATC COMNAVAIRLANT, N422G5G wrote:
> I would really recommend separating the buddy pairs into strings of
> series batteries that can be connected in parallel during use or
> charging.
As I said in my earlier message - which you even included below yours! -
a few years back, I had a problem even with paralleled >strings<.
One battery in one string developed a shorted cell. The good string
would run itself flat trying to charge the bad battery - and I suppose
also
overcharging the others in the bad battery's string.
The batteries survived the experience, but I'm quite sure they lost some
cycle life.
The trouble is that such a situation can easily go unnoticed, unless
some catastrophic event occurs. What alerted me was the reduced
capacity - I guess the good string was supplying all the energy. If I
hadn't noticed that, and had continued to use them as they were, I
probably would have ruined all the batteries in short order.
That said, I use a 36v series-parallel lashup in my Elec-Trak - 3 sets
of paralleled modules in series ("buddy pairs") - and it's worked well
for about 7 years. I think that's mostly dumb luck. To do
series-parallel right, I think you really should have some way of
monitoring the strings and/or modules separately.
David Roden - Akron, Ohio, USA
EV List Administrator
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--- Begin Message ---
Hi EVerybody;
As said before the Citicar had the World's Worst brakes. The early ones
used Gurdis(Sp?) Aircraft discs. They were light and cheap. Reasonable drag,
I mean, after all how much drag can ya get with a shiny roter and the
caliper O ring rolling the piston back? As intended.The Gurdises came as a
neat little package, Tiny by todaze standards, they seemed perfect for the
light Citicar. Nowadaze digging a Citi Car out of the woods, cutting thre
trees away and out of the body to salvage it, the brakes will be welded in
STOP position!The fronts I was relatively at pease with but the rears were
atrocious! The @#$%^ Trailer brake drums, stamped steel warped badly, EVery
stop was a grab-grab-grab thing. If ya adjusted THAT out, well you couldn't
in REALITY adjust that out, you had a 6 foot pedal travel, forgetrabout it!I
don't know what was on Trailer folks minds designing a brake setup that
dragged so badly. Hotter it got in drag mode, the more they warped!Boy !Did
you notice it with a 2 and a half HP motor who was overloaded on level
ground!Had we gone with a cast Iron brake drum in back, the Shitticar brakes
might have been tolorable?The little disc's did their job better than the
rest of the car; No springs ride, the famous" Bump Steer"The crappy doors,
lack of head room. Eaaach! Let's start over again. Bob"Beau" Beaumont did
try. The Tropica was light years ahead of Citicar. It's sad that the 'Trop"
didn't get it's just due? Beau, you were too far ahead of your time. Sigh.
The Citi car, howEVr flawed was a hasty, valiant attempt. The Vulture
capitalists killed it too.BOTH efforts. Have ya read the Book" The Lost
Cord" by Barbara Taylor. Hah! It should/could, in the "Tucker, the Man and
his Dream" venue, be a major motion picture<g>! A true heartbreaker.
X Citicar guy.
Bob
----- Original Message -----
From: "Lee Hart" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Wednesday, February 14, 2007 9:59 AM
Subject: Re: Brake Pressure Multiplier?
> David Roden wrote:
> > For some reason, I'm thinking of the Citicar - it started out with
> > aircraft disc brakes in front, but gave them up in favor of drums
> > all round.
>
> The early CitiCars must have had the worst brakes ever used in a
> "production" automobile. They went *way* too far in the direction of
> cheap and light. I think the first ones were Dico aircraft brakes; they
> only need to stop you *once*, and only need to work for forward. Then
> they went to tiny little trailer brakes with stamped drums, that warped
> badly. The later ComutaCar and ComutaVan went to larger 7" trailer
> brakes, but still had the stamped drums. I replaced the drums with cast
> iron ones on my ComutaVan, and the brakes finally worked reasonably well.
> --
> Ring the bells that still can ring
> Forget the perfect offering
> There is a crack in everything
> That's how the light gets in -- Leonard Cohen
> --
> Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
>
>
>
> --
> No virus found in this incoming message.
> Checked by AVG Free Edition.
> Version: 7.1.411 / Virus Database: 268.17.37/682 - Release Date: 2/12/07
>
>
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--- Begin Message ---
Lee Hart wrote:
> The Volvo is the one car I've heard of that does this. Are
> there others?
I expect that many performance-oriented vehicles will use multi-piston
calipers (perhaps excluding those from North American manufacturers ;^).
Multi-piston calipers are also commonplace on most sportbikes.
> How would people feel if I used drum brakes on the Sunrise kit car?
>
> 1. Great idea! Eliminates dragging brakes, and probably cheaper too.
AFAIK drums haven't been used on the front end by any respectable
manufacturer for *years*; where would you source front drums and
associated suspension parts for the Sunrise? (Early '70's VW Beetle?)
It is just as likely that this will prove *more* costly than using a
readily available and commonplace disc-based front end. (I would expect
that using front end components from a popular model such as the Honda
Civic could be the most practical approach.)
> 2. Horrible idea! No one would even consider not having disk
> brakes nowdays.
Rear discs are probably unnecessary except for their marketing benefits.
By the same token, front drums would have a negative impact on marketing
since they are no longer used on modern production cars.
I would *not* use 4-wheel drums on a modern car because they require
regular maintenance (manual adjustment) to keep them operating properly.
Automatic adjuster schemes for drum brakes never work for long (if
ever), and as the brakes go out of adjustment slightly differently at
each wheel you end up with a very dangerous situation as the car will
pull strongly under braking and depending on the weight distribution of
the car and traction conditions can easily spin out of control. The
most recent car I drove with 4-wheel drums was a '71 Mach 1 and in wet
conditions it would swap ends even under relatively gentle braking if
the brakes were not kept properly adjusted. To be fair, my father's
'67(?) 4x4 half-ton PU with 4-wheel drums never exhibited this
behaviour, but it was also driven considerably differently ;^)
I think front discs are pretty much mandatory these days, both from a
marketing and performance/safety view. If you could find a donor for
the front end that was available in both disc and drum versions, then
individual builders can choose their own poison. Or, find a donor for
which there are multi-piston calipers available as an option for those
builders willing to bear the cost. Again, a recent Honda (or Acura)
donor for the front end components would seem to be a good choice since
aftermarket multi-piston calipers are available to replace the stock
single-piston calipers, for instance:
<http://aj-racing.com/catalog/product.php?productid=977&cat=0&page=2>
My final plea: for Pete's sakes, even NEVs are running front discs and
rear drums! ;^>
Cheers,
Roger.
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On 2/14/07, Don Cameron <[EMAIL PROTECTED]> wrote:
Unsprung weight is the amount of weight that is not supported by the
suspension of the vehicle. This typically includes the tire, wheel, brakes,
part of the drive axle, part of the shock, etc. The lighter the unsprung
weight the more the suspension can react to bumps in the road thus keeping
the tire on the ground more often.
Which also means that the lighter the in-wheel motors, the better.
Which in turn means for good performance, it has to have pretty damn
good power to weight ratio.
Which in turn means, basically best power-to-weight ratio available to
even work acceptably, and you definitely want to lighten your other
unsprung parts as much as possible. Definitely getting rid of
mechanical brakes for example.
This currently means PMSM, i believe these have best power-to-weight.
I remember seeing announcements about induction in-wheel designs as
well, something akin to that:
http://www.greencarcongress.com/2006/04/raser_announces.html
Induction would potentially evntually be cheaper and more robust.
-kert
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Peter,
I'm sure that there is more energy savings by reducing
weight in the drivetrain than by the same reduction in
weight reduction of "carried weight" like freight.
There are many other factors like "moment of inertia"
and the effects of reducing weight at the outside of
the wheels versus the reductions in weight at center
hub area. Some of these are very substantial. A
reduction of a single ounce at the tire perimeter
would be far preferable to a reduction at the hub
center.
The repeated stops and starts at the piston stroke
ends is an area of wasted energy. This may not be a
specific area defined as "sprung vs: unsprung", but
again if you reduce piston weight, you save more
energy than weight of freight.
Some moving parts like the crankshaft have benefits of
having weight that may be required, versus a driveline
for example, where a lighter weight would be always(?)
beneficial and therefor preferable to a reduction in
same weight savings of carried freight.
At any rate, our definition at Michelin was to include
drivelines and other engine/trans components into the
same definition of "unsprung" as wheels and tires.
Additionally, it was a frequent area of concern to
trace vibrations that were mistakenly blamed on tires
too, although the tires are always the first suspect
cause.
What say the engineers?
Regards,
Jay Lashlee, GoWheel.com
[EMAIL PROTECTED]
---------------------------------------
--- Peter VanDerWal <[EMAIL PROTECTED]> wrote:
> > On a truck, if you had extra weight in the
> drivetrain
> > (wheels, tires, driveline, pistons, crankshaft,
> gears,
> > pulleys, fanbelts), it would be "unsprung weight".
>
> Umm, no. Only the weight that is out by the wheels
> and moves with the
> wheels in "unsprung". I.e. the Wheels and tires
> part, but NOT the
> pistons, crankshaft, gears, pulleys, and fanbelts.
> All of the later parts
> are "sprung" since they are fixed to the body and
> carried by the
> suspension.
____________________________________________________________________________________
Bored stiff? Loosen up...
Download and play hundreds of games for free on Yahoo! Games.
http://games.yahoo.com/games/front
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--- Begin Message ---
> "The National Federation of the Blind, an advocacy group, says all
> hybrid vehicles should emit a sound while turned on and is calling on
> the auto industry to make changes. The group says the sound should be
> loud enough to be heard over the din of other ambient noise."
I wonder if that's where that "horse galloping" e-vehicle came up with the
idea. <g>
I'd think they'd prefer to make sure all cars are quiet, so they could
hear the cross-walk signs. Perhaps we just need to make sure all Insights
come with a loud stereo... where the Bass can't be turned down. (Like most
of the other Hondas in our college town.)
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Always something to consider, how to defrost in the winter. Has anyone
come across a ceramic heater core that would be appropriate for pack
voltages between 300 and 400vdc?
Paul Wallace
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I ran a single element extracted from one of those little cube heaters at 192V
nominal in my truck. I would think you could run two in series for a 400V
pack.
----- Original Message -----
From: Paul Wallace <[EMAIL PROTECTED]>
Date: Wednesday, February 14, 2007 12:05 pm
Subject: Any suggestions for electric heater cores for pack voltages over
300vdc?
To: Electric Vehicle Discussion List <ev@listproc.sjsu.edu>
> Always something to consider, how to defrost in the winter. Has
> anyone
> come across a ceramic heater core that would be appropriate for
> pack
> voltages between 300 and 400vdc?
>
> Paul Wallace
>
>
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