EV Digest 4775
Topics covered in this issue include:
1) RE: S-10 Conversion Speed Sensor
by "Dewey, Jody R ATC (CVN75 IM3)" <[EMAIL PROTECTED]>
2) Re: Combining Fiberglass and Steel (was Re: Designing for safety)
by Evan Tuer <[EMAIL PROTECTED]>
3) Re: Combining Fiberglass and Steel (was Re: Designing for safety)
by jerry dycus <[EMAIL PROTECTED]>
4) Re: another Solectria Sunrise All Composite EV Car Body on ebay And
Controller software problems
by jerry dycus <[EMAIL PROTECTED]>
5) RE: Designing for safety (was 'Re: Composite monocoque vs. sand buggy'
by "stU" <[EMAIL PROTECTED]>
6) RE: Combining Fiberglass and Steel- resin and thermal expansion
by "Phil Marino" <[EMAIL PROTECTED]>
7) Re: Designing for safety (was 'Re: Composite monocoque vs. sand buggy'
by Lee Hart <[EMAIL PROTECTED]>
8) Re: Solar Trailer? charge control
by keith vansickle <[EMAIL PROTECTED]>
9) Sidecar Rig
by Aaron Askanase <[EMAIL PROTECTED]>
10) RE: Solar Trailer?
by Mark Hastings <[EMAIL PROTECTED]>
11) Re: Solar Trailer?
by Rush <[EMAIL PROTECTED]>
12) Re: Combining Fiberglass and Steel- resin and thermal expansion
by "Roland Wiench" <[EMAIL PROTECTED]>
13) Re: battery explosion, terminal connections
by Neon John <[EMAIL PROTECTED]>
14) Re: Solar Trailer? charge control
by Lee Hart <[EMAIL PROTECTED]>
15) Re: Battricide? Or are Orbitals tougher than that?
by Lee Hart <[EMAIL PROTECTED]>
16) Re: battery explosion, terminal connections
by Lee Hart <[EMAIL PROTECTED]>
17) Re: Blew up Diode bridge.
by "Michael A. Radtke" <[EMAIL PROTECTED]>
18) Re: S-10 Conversion Speed Sensor
by Neon John <[EMAIL PROTECTED]>
19) Re: Solar Trailer?
by Neon John <[EMAIL PROTECTED]>
20) RE: Solar Trailer?
by Tom Watson <[EMAIL PROTECTED]>
21) Variac brushes
by "rcboyd" <[EMAIL PROTECTED]>
22) RE: Designing for safety (was 'Re: Composite monocoque vs. sand buggy'
by "Kevin Caldwell" <[EMAIL PROTECTED]>
23) Is it really okay to expose motor to the "elements"
by Eric Poulsen <[EMAIL PROTECTED]>
24) Re: Rewinding a shunt motor: costs?
by Neon John <[EMAIL PROTECTED]>
--- Begin Message ---
If I remember right the speed sensor is directly connected to the
speedometer. You have to be sure though because in 95 GM switched speed
sensors in the trucks. I think it is 2000 pulses per mph but I am going
strictly from memory. If you want you can just get a ratio converter, they
sell them in the JEGS catalog for about 100 bucks. If you do a google
search for speedometer corrector you will find a USB programmable one that
will allow you to change the speed by a percentage.
-----Original Message-----
From: Michaela Merz [mailto:[EMAIL PROTECTED]
Sent: Wednesday, September 28, 2005 2:49 PM
To: ev@listproc.sjsu.edu
Subject: S-10 Conversion Speed Sensor
Hello Everybody:
I've got an 120 V 95' S-10, convertion 2/3 done by somebody else
(unfortunately deceased). While this person did a great job on the high
voltage side, he kind of 'rigged' the 12 Volt side. Among other things, he
installed a new speedometer and mounted it on the dash. I am currently
rebuilding the 12 V side so that everything works as it is supposed to.
However, the speedometer gives me a hard time. I connected the speed
sensor input to the original speedometer, but it gives me unvalid speed
readings (approx. 10 times the speed I am actually driving and going to 0
at actual speeds > 15 mph).
My question: On (1995's) S-10, is/was the speed sensor directly connected
to the speedometer or via some internal computer (that has, unfortunately,
been removed) ? What would be a prudent course of action to get the
speedometer working again?
Your insights are appreciated.
Michaela
--- End Message ---
--- Begin Message ---
On 9/29/05, Peter VanDerWal <[EMAIL PROTECTED]> wrote:
> Anyone with experience working fiberglass AND knowledge of these
> properties care to respond?
The Reliant cars do have some steel embedded in glassfibre. The
seatbelt mounting supports for example. The main problems are that
the steel becomes loose in the glassfibre (resin doesn't stick to it
well?), then water / condensation gets to it, then it rots and is
difficult to replace.
I'd be interested to know the answer to the materials question too.
--- End Message ---
--- Begin Message ---
Hi Peter and All,
Even if it wasn't much difference in thermal expension
like Lee has correctly stated, metal and fiberglass just to not work well
together and do not stay attached from either thermal expansion or just normal
road vibrations. So I would not try to mix them in a monocoque type structure.
If you want to attach them, you must do it mechanicly,
not by glueing unless you go to double sided tape or other adveasives that are
designed to do that job. But laying up polyster/glass to metal just is not
going to stay bonded under any kind of sress.
I'm rather busy at the moment so can't answer like I
usually do. The Freedom EV and Sunrise is taking all my time. ;^D
HTH's,
Jerry Dycus
Peter VanDerWal <[EMAIL PROTECTED]> wrote:
> Peter VanDerWal wrote:
>> My plan is to just laminate a steel pipe roll cage inside the foam
>> & composite.
>
> Temperature changes may cause cracking or "oil canning". Steel and
> fiberglass have considerably different expansion coefficients.
Hmm, I hadn't thought of this. However, the difference in CTE between
fiberglass and steel doesn't seem /that/ different to me.
FiberGlass 8.5 x 10-6 per deg C
Mild Steel 12.6 x 10-6
By my calculations, assuming a temperature swing of 55 deg c (ie 0-55 deg
C or 32-131 deg F), this works out to about 0.023% or less than 3/1000"
per foot.
I'm not entirely sure, but I believe this is within the modulus of
elasticity of fiberglass, isn't it?
Especially if I do the layup work at a temperature 1/2 way between these
two extremes, ie ~25 deg C (78 deg F)?
Anyone with experience working fiberglass AND knowledge of these
properties care to respond?
P.S. Thanks for pointing this out Lee.
>
> The worst case would be if you built something like a flat door or roof
> panel with a steel pipe perimeter frame, filled the space inside with a
> foam panel, and then fiberglassed over the outside. As the steel shrinks
> and expand differently with temperature, it will alternately stretch the
> fiberglass until it cracks, and shrink until the fiberglass rattles or
> oilcans in/out.
>
> If you can completely cover the steel with foam, and then fiberglass
> over that, the foam should absorb the dimensional changes with
> temperature.
> --
> The two most common elements in the universe are hydrogen and stupidity.
> -- Harlan Ellison
> --
> Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
>
>
---------------------------------
Yahoo! for Good
Click here to donate to the Hurricane Katrina relief effort.
--- End Message ---
--- Begin Message ---
Hi Tom and All,
Tom Watson <[EMAIL PROTECTED]> wrote:
Hey all
here's another one (sunrise) on ebay;
http://cgi.ebay.com/ebaymotors/Solectria-Sunrise-All-Composite-EV-Car-Body_W0QQitemZ8003377040QQcategoryZ36475QQtcZphotoQQrdZ1QQcmdZViewItem
This is the first body style and not as well finished, less
complete than the one we got., It needs composite structural work before using
as an EV but good if someone wants to make a one off EV though one needs to
know what they are getting into. If anyone does get it, I'd be happy to help
then with info on how to bring it up to snuff. Bob will have pics of it in a
few days as Bob will pick ours up tomarrow and see them both.
The owner of the one listed for sale last yr has contacted me amnd
he has his running but has problems with the controllers, probably in software
with start up power ramp set too low. If anyone can help let me know.
HTH's,
Jerry Dycus
and a gmc ev van;
http://cgi.ebay.com/ebaymotors/EV-Battery-Power-Electric-GMC-Van-Truck-Chevy-Ford-Car_W0QQitemZ8003084863QQcategoryZ6763QQtcZphotoQQrdZ1QQcmdZViewItem
and a 1982 Comuta-Car;
http://cgi.ebay.com/ebaymotors/Other-Makes-Comuta-Car-COMUTA-CAR-VANGUARD-ELECTRIC-CAR-EV-NOT-GEM-CITICAR_W0QQitemZ4578867280QQcategoryZ6472QQtcZphotoQQrdZ1QQcmdZViewItem
Tom
__________________________________________________________
Find your next car at http://autos.yahoo.ca
---------------------------------
Yahoo! for Good
Click here to donate to the Hurricane Katrina relief effort.
--- End Message ---
--- Begin Message ---
For the dimensions given, square is 1.7 times stronger in bending, has
1.7 times less deflection in bending and is 1.3 times stiffer in
torsion. It also weighs 1.3 times as much per foot. Note: Contrary to
"popular" opinion, round is *not* stronger for it's weight.
A 1.5" OD square tube of the same metal area of its cross section as a
1.5" x 0.125" round tube would have a wall thickness of 0.09616". This
would then be the same weight per foot as the round tube and be 1.4
times stronger and stiffer in bending but only 0.96 times (4% less) as
stiff in torsion.
Of course, the above is 'steel to steel'. I believe that even 'low' quality
mild steel is strong enough for safety. Do you have DOM quality in any mass
produced vehicle?
Why not 'kick it up a notch' and go for thin wall Cr/Mo?
DOM round tubing is stronger but much more expensive, much harder to joint
and to fish mouth, (easier to bend), and certainly not the best shape for a
one off build in your garage.
Also, attaching to a flat surface by adhesive or screws is trivial compared
to 'skinning' a round tube.
stU
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Ryan Stotts
Sent: Wednesday, September 28, 2005 10:50 PM
To: ev@listproc.sjsu.edu
Subject: Re: Designing for safety (was 'Re: Composite monocoque vs. sand
buggy'
stU wrote:
> Square or round, size and wall thickness?
>
> I'm thinking 1-1/2" square 0.125" wall.
Scroll way down on this page to where it says "Round Tube vs. Square
Tube". Some VERY interesting info...
http://www.factoryfive.com/table/ffrkits/roadster/specs/frame.html
The frame on that page unbelievably weighs 350 lbs and the fiberglass
body weighs 110 lbs..
--- End Message ---
--- Begin Message ---
>> My plan is to just laminate a steel pipe roll cage inside the foam
>> & composite.
>
> Temperature changes may cause cracking or "oil canning". Steel and
> fiberglass have considerably different expansion coefficients.
Hmm, I hadn't thought of this. However, the difference in CTE between
fiberglass and steel doesn't seem /that/ different to me.
FiberGlass 8.5 x 10-6 per deg C
Mild Steel 12.6 x 10-6
By my calculations, assuming a temperature swing of 55 deg c (ie 0-55 deg
C or 32-131 deg F), this works out to about 0.023% or less than 3/1000"
per foot.
I'm not entirely sure, but I believe this is within the modulus of
elasticity of fiberglass, isn't it?
Especially if I do the layup work at a temperature 1/2 way between these
two extremes, ie ~25 deg C (78 deg F)?
Anyone with experience working fiberglass AND knowledge of these
properties care to respond?
"Fiberglass" structures are not made of glass fibers alone. The matrix
(resin used in a composite) is usually either polyester resin (often used in
boat building) and epoxy resin. In hand layups these resins generally make
up at least half of the weight ( and even more of the volume) of the
composite.
A "fiberglass" power boat has more pounds of polyester resin in it than
glass fibers.
Polyester resin is less expensive than epoxy resin, and has much poorer
engineering properties. It shrinks more during cure, has lower adhesion,
less strength, less stability, and can be brittle. The curing agent (
catalyst) is usually MEK, and very little catalyst is used ( less than 1% by
volume). It's the resin in "bondo" and generally what is used for car body
repair. When people say " fiberglass resin" (kind of like saying "military
intelligience") they usually mean polyester resin.
Epoxy resins are more often used in lightweight, high quatlity boat
construction ( West Epoxy is a common brand used in the marine field). They
are more expensive, and have better adhesion, and better mechanical
properties, in general, than polyester resins. They are usually mixed from
two components in similar volumes (sometimes 1:1 ratios, often 2:1 ratios) .
When I was kid, I built boats using polyester resin (mostly for sheathing
the hulls with fiberglass cloth for strength and abrasion resistance). More
recently I've been building "stitch and glue" boats using epoxy resin.
Good epoxy resin ( in small quantities) costs about $100/ gallon. Polyester
resin is more like $20/gallon or less.
The first question to ask about a fiberglass composite is - what resin was
used?
The resins have a much higher thermal coefficient than glass fibers, and
can't be ignored when calculating the CTE of the structure.
If you really want to calculate the CTE ( coefficient of thermal expansion)
you have to know the properties of the fibers, the properties of the resin,
the resin-fiber ratio, and the layup. ( What percentage of the fibers are
oriented in each direction). The CTE can ( and, often is) very different in
different directions.
As an example, the through-the-thickness CTE of a flat panel would very
close to the CTE of the resin alone, but the CTE in-plane would be much
lower, and depend on the resin-fiber ratio.
Years ago, I designed composite structures for large optical systems. We
often ended up with tubes and struts that had 0.00 CTE in one direction (
for example, the direction that controlled focus) so that the optical
alignment would not change with temperature. The was achievable because
the fibers used(graphite) have a negative CTE. (Yes, they get shorter as
their temperature rises). So, with the right fiber-matrix ratio, and the
right layup, you could get the composite to have just about any CTE you
wanted - at least in one direction.
For those who are interested, there is lots of information on the web about
resins, and about composites in general.
Phil
_________________________________________________________________
Dont just search. Find. Check out the new MSN Search!
http://search.msn.click-url.com/go/onm00200636ave/direct/01/
--- End Message ---
--- Begin Message ---
Tim Stephenson wrote:
> Would you want to:
> - Provide a cushion, like closed-cell foam used on pipe insulation,
> for example?
> - Box around the package with foamboard (that is, provide an
> oversized channel)?
I think any of these would help. It might even be enough to insure that
the fiberglass outside skin was always curved such that the
expansion/contraction of the steel could be accommodated by flexing the
fiberglass without cracking it.
> or
> - Use expandable foam inside the "box" (the spraycan stuff used for
> insulation around a home's windows and doors)?
I think the key is that you don't want two materials with different
expansion rates tightly bonded together and arranged so they are both
very stiff. The foam inside isn't part of the problem; it's that the
steel expands a lot more than the fiberglass with temperature.
--
Never doubt that the work of a small group of thoughtful, committed
citizens can change the world. Indeed, it's the only thing that ever
has! -- Margaret Mead
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
--- End Message ---
--- Begin Message ---
thanks peter
--- Peter VanDerWal <[EMAIL PROTECTED]> wrote:
>
> > I am coming to this discussion pretty late and
> have
> > not read the whole thread so excuse me if i ask
> for
> > infromation you have already given. I have a
> trike
> > with a 35 watt+- solar panel and 48 volts of agm
> batts
> > right now I have not hooked the panel to the batts
> as
> > the regulator from the solar company says it is
> only
> > good for up to 24v.
> -snip-
> > read below I infer that a set of lee hart
> regulators
> > will act as a charge controller. yes no ??
>
> Actually we were talking about Lee's battery
> balancer which is different
> from Lee's battery regulators.
> The Balancer is one device that connects to all of
> your batteries at the
> same time. Is uses a microprocessor, a voltmeter, a
> charger and a bunch
> of relays.
>
> At this point it is a do it yourself project,
> however I think Lee might be
> getting ready to order a new set of circuit cards.
>
> For you a simpler solution might be to use two
> panels like the one you
> already have or buy a bunch of little panels.
>
> If you are interested, the cheapest place I've found
> solar panels (~ $2.60
> per watt) is:
>
http://www.theenergyalternative.com/energy_efficient_products/index.html?item=412
> 20 Panels for $65
> Each panel is 5.6V @ 0.22 Amps
>
> Wire them up as two series strings of 10 each add a
> blocking diode and you
> can connect them directly across your pack. WIth
> only 10 you won't quite
> bring the pack up to full charge, you could buy
> another set of two and
> that should give you enough to fully charge the
> pack, though it might
> overcharge it slightly if you don't use the trike
> for a couple days but
> leave it in the sun.
>
> 20 of these panels equals roughly 25 watts. If you
> get 5 hours worth of
> sun then you'll put approx 100 watthours back into
> the pack. That's not a
> lot of energy.
>
>
> > --- Lee Hart <leea [EMAIL PROTECTED]> wrote:
> >
> >> Peter VanDerWal wrote:
> >> > How do you handle the fact that the battery
> being
> >> charged is now
> >> > going to have the highest voltage in the pack?
> Do
> >> you have a time
> >> > delay before it can switch to another battery
> or
> >> do you some how
> >> > compensate for charging voltage?
> >>
> >> Yes. The basic algorithm is:
> >>
> >> - scan the batteries to get their voltages
> >> - compute the average voltage
> >> - find the lowest-voltage battery
> >> - charge it for a time proportional to how much
> >> below average it is
> >> (usually no more than 10 minutes per battery)
> >> - repeat
> >>
> >> So it scans the batteries every 10 minutes, and
> >> charges the lowest ones
> >> for a time proportional to how much below average
> >> they are.
> >>
> >> > I never thought about using your balancer as
> the
> >> sole source for
> >> > charging. You might have mentioned this before
> and
> >> I missed it.
> >>
> >> Yes, it can be used your only charger, or an
> >> opportunity charge. Very
> >> slow though, as it has to charge them one at a
> time.
> >>
> >> > This seems ideal for AGMs, especially Hawkers.
> You
> >> could slug them
> >> > with a high current charge and then move on and
> >> allow them to cool,
> >> > then come back and slug them again. Charging
> and
> >> equalization at
> >> > once, I like it.
> >>
> >> Yes, that's basically it!
> >> --
> >> If you would not be forgotten
> >> When your body's dead and rotten
> >> Then write of great deeds worth the reading
> >> Or do the great deeds worth repeating
> >> -- Ben Franklin, Poor Richard's Almanac
> >> --
> >> Lee A. Hart, 814 8th Ave N, Sartell MN 56377,
> >> leeahart_at_earthlink.net
> >>
> >>
> >
> >
> >
> >
> > __________________________________
> > Yahoo! Mail - PC Magazine Editors' Choice 2005
> > http://mail.yahoo.com
> >
> >
>
>
> --
> 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.
>
>
__________________________________
Yahoo! Mail - PC Magazine Editors' Choice 2005
http://mail.yahoo.com
--- End Message ---
--- Begin Message ---
Has anyone built a electric side car rig? It would seem an easy way
to carry around a lot of batteries, and the weight would offset some
of the inherent instability of sidecars. The electric motor would
also make for an easy reverse gear. Plus, to carry on with a current
thread, you could possibly mount a solar panel on top of the sidecar,
out of the wind, to give a little (tiny) extra charge.
Aaron
--- End Message ---
--- Begin Message ---
The motorcycle is going to be roughly 48 volts with dual eteks. I think there
are even 48 volt panels available although I'm not sure if they would help
charging and are probably expensive and hard to get. I'm not looking to fully
charge the motorcycle I just need a pick me up at work.
- It will mean my batteries won't discharge as much meaning they'll last longer
in theory.
- It will mean if I am close to my range limit I won't have to worry about
making it home if I get any solar power at all.
- It will be a nice little alternative energy/transportation display. (More
pressure to build a nice conversion)
- I can probably start with the panels off my S-15.. All they do now is make
people ask me on cloudy days if I'll make it home.
I'm not sure I'm going to do a trailer seems like a lot of extra stuff since
I'm not going to need batteries or an inverter. I am thinking a lock box left
attached to something sturdy at work. I can park next to it and fold out the
panels when I come to work and lock them back up when I am done. Our building
is in the middle of no where with nothing around it. I may even bring them
inside everynight but I know people would think that was very inconvinient at
my work and I don't want it to seem inconvinient even if it isn't.
"Dewey, Jody R ATC (CVN75 IM3)" <[EMAIL PROTECTED]> wrote:
I don't think he mentioned exactly what voltage level he was going to run on
the motorcycle or how many batteries. I was merely stating hypotheticals.
I am thinking that a trailer with solar will be an interesting concept but
not really practical. It might be easier just to have it set up that way at
home.
--- End Message ---
--- Begin Message ---
How do you know that the inverter is incompatable?
And as to it's awesomeness, Peter VanDerWal did a quick $$ study -
"Hmm, that's kinda neat, but an opening bid of $7,500?
Let's see:
Solar panels $1300
Batteries $ 400
Inverter $ 100 (it's a *modified* sine wave!!)
Trailer $ 200
====================
Total $2000
275% profit. Damn, I'm in the wrong bussiness."
While his numbers may not be totally accurate, he is right that it is totally
overpriced.
Rush
Tucson AZ
www.ironandwood.org
----- Original Message -----
From: "Dewey, Jody R ATC (CVN75 IM3)" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Thursday, September 29, 2005 4:09 AM
Subject: RE: Solar Trailer?
> That is an awesome trailer! The inverter installed on it is incompatible
> with a 115V charger though. It would be a great way to get a good idea
> about how to make one for the motorcycle project though.
>
> -----Original Message-----
> From: Meta Bus [mailto:[EMAIL PROTECTED]
> Sent: Wednesday, September 28, 2005 2:04 PM
> To: ev@listproc.sjsu.edu
> Subject: Re: Solar Trailer?
>
>
> http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=6002539033
>
> A solar trailer for y'all.
>
>
>
--- End Message ---
--- Begin Message ---
In 1985 when I design my EV as a series hybrid, I had to raise the entire hood
of the car to clear the engine. I used a four foot by five foot fiberglass
panel that was attach to the steel hood with rivet every 1 inch.
Lay the panel in bed of epoxy fiberglass and finish the edges with finishing
epoxy compounds.
This hood extension held up until we had a temperature change in one day of 80
degrees, It went from 50 degrees to 30 below. The fiberglass hood just
exploded and separated from the steel.
Today, must of the new cars plastic panels are bonded and only glue to the
inner steel panels. They are curved at the edge, so it gives a flexible joint.
I ask a friend of mind who owns a customizing body shop that is modifying my
fiberglass sports car, what products manufacturer use and he uses.
He uses Duramix Compounds that come in a double barrel tube that mixes threw a
spiral replaceable tip that is place in a double barrel type of cauking like
gun.
The Duramix Compounds come in different specifications. One for fiberglass to
steel, fiberglass to aluminum, fiberglass to fiberglass, plastic to plastic,
plastic to steel and so on.
Raise plastic panels, scoops and etc. are only bond to metal with a 1/8 to 1/4
inch bead of this compound on the contact area only. Normally the panel you
attach is already finish and painted with a nice roll over edge that may
contact the metal or stay about 1/16 of a inch away.
If you want to finish these edges which will not leave a expansion crack, than
you can used a product call Evercoat - Fiber Tech.
This is a super flexible reinforced repair compound that is also design for
flexible adhesive to steel, galvanize steel, aluminum, composites and steel.
This Fiber Tech is follow up by a compound call ICE. which is a super flowing
finishing compound for metals, plastic and fiberglass.
I than tried these compounds and there fantastic. The ICE goes on so smooth,
it is like glass.
These products Duramix, Evercoat-Fiber Tech and Usc ICE are the best you can
get. Every body shop and auto body paint supplier knows about these products.
All the metal attachments to the fiberglass used these compounds in my
fiberglass car and the front fiberglass panel on my EV.
Roland
----- Original Message -----
From: Phil Marino<mailto:[EMAIL PROTECTED]>
To: ev@listproc.sjsu.edu<mailto:ev@listproc.sjsu.edu>
Sent: Thursday, September 29, 2005 7:02 AM
Subject: RE: Combining Fiberglass and Steel- resin and thermal expansion
>
> >> My plan is to just laminate a steel pipe roll cage inside the foam
> >> & composite.
> >
> > Temperature changes may cause cracking or "oil canning". Steel and
> > fiberglass have considerably different expansion coefficients.
>
>Hmm, I hadn't thought of this. However, the difference in CTE between
>fiberglass and steel doesn't seem /that/ different to me.
>FiberGlass 8.5 x 10-6 per deg C
>Mild Steel 12.6 x 10-6
>
>By my calculations, assuming a temperature swing of 55 deg c (ie 0-55 deg
>C or 32-131 deg F), this works out to about 0.023% or less than 3/1000"
>per foot.
>
>I'm not entirely sure, but I believe this is within the modulus of
>elasticity of fiberglass, isn't it?
>Especially if I do the layup work at a temperature 1/2 way between these
>two extremes, ie ~25 deg C (78 deg F)?
>
>Anyone with experience working fiberglass AND knowledge of these
>properties care to respond?
>
"Fiberglass" structures are not made of glass fibers alone. The matrix
(resin used in a composite) is usually either polyester resin (often used in
boat building) and epoxy resin. In hand layups these resins generally make
up at least half of the weight ( and even more of the volume) of the
composite.
A "fiberglass" power boat has more pounds of polyester resin in it than
glass fibers.
Polyester resin is less expensive than epoxy resin, and has much poorer
engineering properties. It shrinks more during cure, has lower adhesion,
less strength, less stability, and can be brittle. The curing agent (
catalyst) is usually MEK, and very little catalyst is used ( less than 1% by
volume). It's the resin in "bondo" and generally what is used for car body
repair. When people say " fiberglass resin" (kind of like saying "military
intelligience") they usually mean polyester resin.
Epoxy resins are more often used in lightweight, high quatlity boat
construction ( West Epoxy is a common brand used in the marine field). They
are more expensive, and have better adhesion, and better mechanical
properties, in general, than polyester resins. They are usually mixed from
two components in similar volumes (sometimes 1:1 ratios, often 2:1 ratios) .
When I was kid, I built boats using polyester resin (mostly for sheathing
the hulls with fiberglass cloth for strength and abrasion resistance). More
recently I've been building "stitch and glue" boats using epoxy resin.
Good epoxy resin ( in small quantities) costs about $100/ gallon. Polyester
resin is more like $20/gallon or less.
The first question to ask about a fiberglass composite is - what resin was
used?
The resins have a much higher thermal coefficient than glass fibers, and
can't be ignored when calculating the CTE of the structure.
If you really want to calculate the CTE ( coefficient of thermal expansion)
you have to know the properties of the fibers, the properties of the resin,
the resin-fiber ratio, and the layup. ( What percentage of the fibers are
oriented in each direction). The CTE can ( and, often is) very different in
different directions.
As an example, the through-the-thickness CTE of a flat panel would very
close to the CTE of the resin alone, but the CTE in-plane would be much
lower, and depend on the resin-fiber ratio.
Years ago, I designed composite structures for large optical systems. We
often ended up with tubes and struts that had 0.00 CTE in one direction (
for example, the direction that controlled focus) so that the optical
alignment would not change with temperature. The was achievable because
the fibers used(graphite) have a negative CTE. (Yes, they get shorter as
their temperature rises). So, with the right fiber-matrix ratio, and the
right layup, you could get the composite to have just about any CTE you
wanted - at least in one direction.
For those who are interested, there is lots of information on the web about
resins, and about composites in general.
Phil
_________________________________________________________________
Don't just search. Find. Check out the new MSN Search!
http://search.msn.click-url.com/go/onm00200636ave/direct/01/<http://search.msn.click-url.com/go/onm00200636ave/direct/01/>
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On Wed, 28 Sep 2005 12:35:37 -0600, "Roland Wiench" <[EMAIL PROTECTED]>
wrote:
>I don't know why Trojan is making battery post that way. My post was so soft,
>that they mushroom or keep squeezing smaller. Not like the Exide batteries I
>had before.
>
>I seen these L post on a EV, where the owner had them nearly squeeze flat. So
>make sure the post connection is a hard material.
>
>The L post will might work if you used a square saddle washer where the edges
>lip over the L post terminal edges to keep them from deforming.
Even that doesn't work. L terminal lead creep is the single worst
problem I've had with my GoBig scooter containing Hawkers. Tightening
the terminals is an every-other-week chore. I've installed cut-down
fender washers on both sides of each terminal to spread the load out
as much as possible and still the damn things squish out. The
combination of creep and the resulting heat leaves the cables actually
loose in some cases, free to move in all cases.
I think that the standard SAE battery posts are the best for high
current applications. That design has the largest cross-section of
metal and the largest surface area for the cable lug to mate against.
Crimped-on copper cable lugs have been absolutely trouble-free in my
Citi which fairly routinely pulls >300 amps from golf cart batteries.
John
---
John De Armond
See my website for my current email address
http://www.johngsbbq.com
Cleveland, Occupied TN
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keith vansickle wrote:
> I have a trike with a 35 watt solar panel and 48 volts of agm batts.
> The regulator from the solar company says it is only good for up to
> 24v... I infer that a set of Lee Hart regulators will act as a charge
> controller. yes? no?
There are several ways you can handle this.
1. You can use a switch to connect the batteries in series (48v)
while driving, or as 2 parallel groups of 2 in series (24v) when
charging.
Then your regulator can charge them all normally.
2. You could use a vastly simplified version of my Battery Balancer
with just a single relay and an oscillator to make it cycles on/off
slowly. When 'on' it connects the PC panel and regulator to charge
one 24v string of batteries; when 'off' it charges the other 24v.
3. You can put a shunt regulator, like Rudman regulators or equivalent,
in parallel with each 12v battery, and use them to limit the charge
voltage to the batteries. You'd set them to a good float voltage
for the batteries you are using (around 13.5v).
> Can I buy same or must I build them?
Either. All 3 solutions above are pretty simple to build. Wiring them
into the trike will be more complicated than building them.
> BTW lee I have most of the pedal generator hardware and would like
> to send it to you for the electronic part as I am an electronic idiot.
> Would that be ok?
Write me off-list on this. My plate is pretty full right now, so I don't
want to take on any more big projects until I get a few existing ones
done!
--
Never doubt that the work of a small group of thoughtful, committed
citizens can change the world. Indeed, it's the only thing that ever
has! -- Margaret Mead
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
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Ryan Bohm wrote:
> It seems the magic number I've heard under load is 10.5V before you
> are at 0% SOC... under what sort of load does this 10.5V hold true?
10.5v is a convenient number because it is 0% SOC *at that load
current*. In other words, it applies at any current.
> Should I curtail my low-voltage abuse, set the low voltage limit at
> around 120V?
I would! Those are expensive batteries to murder. You should still have
all your performance and "fun" as long as the pack is mostly charged.
--
Never doubt that the work of a small group of thoughtful, committed
citizens can change the world. Indeed, it's the only thing that ever
has! -- Margaret Mead
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
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Rich wrote:
> Has anyone ever heard of one or tow batterys in series reversing
> themselves....they really get hot...
Sure! A lead-acid battery can be discharged so far that its polarity
reverses. Actually, it has gone dead, and is being "charged" in the
reverse direction by the current that keeps flowing due to the other
batteries in series that can still supply power.
Reversing a battery reduces its amphour capacity so much that it becomes
useless. It will have low capacity and excessive internal resistance,
and so will indeed get hot if you keep using it anyway. Your EV will
perform better if you simply remove it, and adjust your charger and
controller to get by with the reduced pack voltage.
--
Never doubt that the work of a small group of thoughtful, committed
citizens can change the world. Indeed, it's the only thing that ever
has! -- Margaret Mead
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
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Lawrence,
I agree with James. But ...
The internal wiring of all variacs should be the same. The common on
the input side should be a pass through to the common on the output
side. The input is applied across the entire coil, and the hot output
is the slider. If your variacs are wired this way you are OK. If one
of the variacs is wired with the hot and common swapped, the outputs can
still be chosen so that they are phase. However, at non unity, but
equal, settings of both variacs there will be a voltage offset BETWEEN
the two variac outputs. This will lead to undesirable results if you
try to combine them.
Mike
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On Wed, 28 Sep 2005 13:49:03 -0500 (CDT), "Michaela Merz"
<[EMAIL PROTECTED]> wrote:
>However, the speedometer gives me a hard time. I connected the speed
>sensor input to the original speedometer, but it gives me unvalid speed
>readings (approx. 10 times the speed I am actually driving and going to 0
>at actual speeds > 15 mph).
>
>My question: On (1995's) S-10, is/was the speed sensor directly connected
>to the speedometer or via some internal computer (that has, unfortunately,
>been removed) ? What would be a prudent course of action to get the
>speedometer working again?
No computer involved. The variable reluctor sensor used for the
speedo pickup generates a pulse whose amplitude is roughly
proportional to the speed. The speedo usually has some sort of
automatic gain control to accommodate the low voltage pulses at low
speed. It is most likely that when the gain is up, the speedo is
picking up interference from the motor controller.
The first thing to do is to make sure the speedo wiring is located far
away from any traction wiring. If that doesn't fix things then you
should try running shielded twisted pair from the pickup to the
speedo. If the problem is still there then you'll have to start
looking for ground loops and/or tramp connections between the traction
and 12 volt wiring.
One other thing to check is to make sure your DC/DC converter isn't
outputting trash onto the 12 volt side.
John
---
John De Armond
See my website for my current email address
http://www.johngsbbq.com
Cleveland, Occupied TN
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On Wed, 28 Sep 2005 12:30:26 -0700 (MST), "Peter VanDerWal"
<[EMAIL PROTECTED]> wrote:
>> http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=6002539033
>>
>> A solar trailer for y'all.
>
>
>Hmm, that's kinda neat, but an opening bid of $7,500?
>
>Let's see:
>Solar panels $1300
>Batteries $ 400
>Inverter $ 100 (it's a *modified* sine wave!!)
>Trailer $ 200
>====================
>Total $2000
>
>275% profit. Damn, I'm in the wrong bussiness.
With math like that, I certainly hope you don't find the "right
business".
I see at least $400 in the bare trailer, tires and wheels. I see at
least a couple hundred dollars in NEMA 1 & 4 boxes. A couple hundred
more in misc wiring. Probably another $100 in paint, if they used a
quality automotive or even industrial paint. I see probably 40 hours
of labor in putting all that together, at least for the first few.
What's your labor worth?
If you want to make a business out of making solar trailers, you'd
better figure on at least doubling your direct cost and more typically
tripling it to cover overhead, taxes and all the other stuff.
$7.5k seems quite reasonable for what amounts to a hand-built custom
product, if a solar trailer is what you want. $700 for a Honda
EU2000i and a couple of cans of gasoline certainly sounds better to
me.
John
---
John De Armond
See my website for my current email address
http://www.johngsbbq.com
Cleveland, Occupied TN
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Hey Peter
I'm sorry I should have been more clear on this
suggestion...
You would need two circuits, a charge circuit and a
drive circuit. The drive circuit would have the diode
allowing current out of the battery, and the charge
circuit would only allowing current in to the battery
... a transistor with some digital circuitry would
allow this... come to think of it, you could skip the
diode and just use the transistors!
Tom
> And, is there something wrong with using a diode to
> protect your batteries from trying to charge a low
> cell??? like they do with solar cells to keep them
> from trying to discharge your batteries.
> Tom
You mean asside from the fact that the diode would
block current from flowing when you were trying to
charge the pack?
__________________________________________________________
Find your next car at http://autos.yahoo.ca
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Can anybody guide me to a place to buy a set of brushes for a Superior
Electric Company Powerstat variable transformer, type 1256, 240 volt, 28
amp? Any help will be greatly appreciated.
Bob Boyd
[EMAIL PROTECTED]
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You are confusing safety with strength. They are not the same thing. Crash
safety requires a crushable structure to absorb the energy, as well as a
safety cell to protect the occupants. Adding more material will not
necessarily make a safer vehicle, in fact it can raise the G load that the
occupant is subjected to and cause more injury.
There is no substitute for engineering when it comes to designing a crash
structure.
Kevin Caldwell
Courtenay, BC
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of stU
Sent: September 28, 2005 12:56 PM
To: ev@listproc.sjsu.edu
Subject: RE: Designing for safety (was 'Re: Composite monocoque vs. sand
buggy'
> Tim Stephenson wrote:
>
My plan is to just laminate a steel pipe roll cage inside the foam &
composite.
Might not be the lightest, but it WILL be safe(r) and not much heavier.
You can do a good steel roll cage in about 100 lbs give or take. A lot Less
for really small vehicles.
Ditto here. Square or round, size and wall thickness?
I'm thinking 1-1/2" square 0.125" wall.
stU
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With many conversions, the motor is often located near the underside of
the car. I've read here that you shouldn't worry too much about the
motor, but is it really okay with getting wet/dirty? What happens when
you hit a big puddle, and have direct splash onto the motor?
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On Wed, 28 Sep 2005 22:12:13 -0400, Chris Zach <[EMAIL PROTECTED]>
wrote:
>Well, I'm coming to the conclusion that my Elec-Trak E20's main motor
>has a ground short in the armature windings. The resistance to ground is
>slightly different from either side, and when I ground out positive
>while the motor is running, the speed changes.
Probably not the armature if only the speed changes. Easy enough to
check with an ohmmeter once you disconnect the wiring.
>
>Drat.
>
>Any idea what it would cost to get a 3-4hp GE motor rewound? I'd rather
>not be taken to the cleaners, but it seems the famed "no maintenance"
>motor here needs maintenance. By an odd coincedence, the lift motor also
>went to ground; problem there is definately a shorted to ground armature.
>
>Any thoughts? What's the lifespan on the average motor windings anyway?
Depends on how well the motor is maintained :-) I've seen 50 year old
motors come in the shop for a bearing replacement and commutator
dressing that meggered as good as new. OTOH, I know one local company
that won't listen to advice that burns out a 400 hp motor at least
annually because they have it geared wrong and are running it at full
armature current at only about 500 RPM with no extra cooling.
A shorted armature to ground will usually result in periodic heavy
arcing at the brushes, growling noises and generally a lower speed. I
don't think that's what you have. If the motor has a wound field, I'd
look there first. If it's a PM, I'd look for a ground in the brush
assembly.
I'd take the motor off, disassemble it and do an inspection, meggering
or ohming if you don't have a megger, every electrical component
individually. Before I disassembled the motor, I'd check each
terminal to ground. If there is no ground that will save you the
labor of disassembling it.
Rewinding costs vary with what you're willing to do and the problem. A
complete rewind with you dropping the motor off and picking it up
would run probably $500 at least. If you disassemble the motor and
take in only the defective part, the price will be a fraction of that.
If there is an armature fault, it's probably going to be cheaper to
just buy a new motor. There is a lot of manual labor in armature
rework that is not involved with the automated assembly lines used by
most all motor manufacturers.
John
---
John De Armond
See my website for my current email address
http://www.johngsbbq.com
Cleveland, Occupied TN
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