EV Digest 3945
Topics covered in this issue include:
1) Re: kWh/mile challenge
by Jeff Shanab <[EMAIL PROTECTED]>
2) Re: Motor Amps, Battery Amps ?
by Nick Viera <[EMAIL PROTECTED]>
3) Re: Make your own fuse.
by "Lawrence Rhodes" <[EMAIL PROTECTED]>
4) Bad gear ratio on Stock Lectra.
by "Lawrence Rhodes" <[EMAIL PROTECTED]>
5) Re: Make your own fuse.
by James Massey <[EMAIL PROTECTED]>
6) Re: DC clamp meter recomendation
by "M.G." <[EMAIL PROTECTED]>
7) BLDC motor with integrated control on Ebay
by Rod Hower <[EMAIL PROTECTED]>
8) Re: Make your own fuse.
by "M.G." <[EMAIL PROTECTED]>
9) Re: Sealed PbA battery Options
by "John Bryan" <[EMAIL PROTECTED]>
10) Re: kWh/mile challenge
by "Richard Furniss" <[EMAIL PROTECTED]>
11) Revitalizing EV batts. and regulators
by strowbridge <[EMAIL PROTECTED]>
12) Re: kWh/mile challenge
by "Joe Smalley" <[EMAIL PROTECTED]>
13) Re: DC clamp meter recomendation
by Eric Poulsen <[EMAIL PROTECTED]>
14) Re: kWh/mile challenge
by David Dymaxion <[EMAIL PROTECTED]>
15) test bench notes:
by "Rich Rudman" <[EMAIL PROTECTED]>
16) Re: DC clamp meter recomendation
by "Steve Clunn" <[EMAIL PROTECTED]>
17) Re: kWh/mile challenge
by "Steve Clunn" <[EMAIL PROTECTED]>
18) RE: DC clamp meter recomendation
by "Markus L" <[EMAIL PROTECTED]>
19) Re: kWh/mile challenge
by "Richard Furniss" <[EMAIL PROTECTED]>
20) Re: kWh/mile challenge
by "Richard Furniss" <[EMAIL PROTECTED]>
21) test message, please ignore
by "Cliff Rassweiler" <[EMAIL PROTECTED]>
22) Re: kWh/mile challenge
by Lee Hart <[EMAIL PROTECTED]>
23) test please ignore
by "ProEV" <[EMAIL PROTECTED]>
24) Re: DC clamp meter recomendation
by Lee Hart <[EMAIL PROTECTED]>
25) Re: DC clamp meter recomendation
by Lee Hart <[EMAIL PROTECTED]>
--- Begin Message ---
Place a disqualification rule for people exceeding recommended tire
pressure, checked at end of run? (have a witness?)
divide into classes
A430 Aero 4 wheel 30psi max
A450 Aero 50 psi max
S430 sedan 4 wheel 30psi max
S450
T430 truck
T450
M2 motorcycle
M3 motorcycle + sidecar
Even if a competiition is not held this kind of info would be invaluable
for helping design and diagnose. If 10 people with 120V rabbits are
getting 200 wh/mile and you are getting 300 in yours, you might suspect
something is up.
--- End Message ---
--- Begin Message ---
Hi,
Roderick suggested that my motor timing might be set incorrectly. Since
I wasn't sure how it was set, and the tail-shaft end of my motor is easy
to get to, I decided to investigate.
I found that my motor does have three sets of holes drilled in the case,
to allow the tail end of the motor to be adjusted to 3 positions.
Looking at the *tail-shaft* end of the motor, the bolts were bolted into
the most counter-clockwise set of holes. So my timing is set to the most
advanced position. Darn, I was hoping it would be set wrong which would
have been an easy fix :-/
After reinstalling the bolts and torque rod, I went for a 5.2 mile drive
during which I made a point of driving the motor to higher RPMs. I
noticed something very strange:
I was flooring it in 1st gear from a stop (the yellow LED is OFF), and
instead of shifting into 2nd at 25 mph (~4000 RPMs) as usual, I stayed
in 1st. Well, the minute the motor rose above 4300 RPMs, the Yellow LED
came ON SOLID, and my ammeter (which was showing ~350 battery amps)
immediately pegged well over 400 amps. Of course I let off after a
couple seconds because the motor was at 5000 rpms, and I didn't want to
damage my batteries. And I was able to repeat this. So It seems that at
any motor speed above 4300 rpms, I CAN make the controller give full
power. However, this still does me NO good, as take offs in anything but
1st (or maybe 2nd) gear are still impossible, and acceleration continues
to be lousy.
When I got back in the garage, I immediately put a temperature probe on
the tail shaft of the motor. It read 135 degrees F after that 5.3 mile
drive. It was hot, and the motor DID smell some again.
Now, another suggestion was to take amp readings with the transmission
in gear, and the rear wheels off the ground (no load, but drivetrain
spinning).
Motor ------- BATTERY amps ------
RPMs: (1st gear) (2nd gear)
1000 3 6
1500 5 9
2000 9 12
2500 10 15
3000 20 -
3500 20 -
4000 24 -
What confuses me is the fact that I was seeing LESS battery amps when
the motor was spinning the entire drivetrain under no load, VS when just
the motor and flywheel were spinning under no load. Maybe this is due to
there being more inertia in the system due to the heavy, spinning tires?
I guess this shows that there is nothing wrong with the drivetrain since
the current didn't increase significantly? (oh BTW, the Jeep does seem
to coast well.) Do we still think it is the motor?
-Nick
1988 Jeep Cherokee 4x4 EV
http://Go.DriveEV.com/
------------------------------------------------
On Fri, 2004-12-03 at 23:44, Rich Rudman wrote:
> ----- Original Message -----
> From: "Nick Viera" <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Sent: Friday, December 03, 2004 5:45 PM
> Subject: Re: Motor Amps, Battery Amps ?
>
>
> > Hi,
> >
> > > How hot does the motor get??
> >
> > I have noticed that the motor seems to get hot -- in opinion too hot.
> > Even after a shorter (~6 mile drive), the motor shaft and both casing
> > ends are too hot to touch. I'll try to get an actual temp. reading from
> > my multimeter (which has a temp. probe)...
> >
> > Now that I think about it, I have also noticed sort of a "burning
> > brakes" smell coming from the motor after longer (~10+ mile) trips. This
> > is especially noticeable after trips which have included hills or
> > inclines, which have included me pulling up to 380 amps on the battery
> > side. This smell is definitely NOT the front brakes. I've had those
> > fixed and they no longer smell. The smell comes straight up from the
> > motor. I thought at first that it might be due to the motor still being
> > relatively new, but now that I've got 468.4 EV miles on the Jeep (I keep
> > a good log), I can't imagine that being the case.
> >
> > > No load and a good speed should be like 25 to 50 amps...Motor amps,
> > > almost nothing battery amps.
> >
> > I just hooked back up the Tachometer sensor (which works ok when it
> > feels like it), and did a little test. With the transmission in neutral,
> > the motor pulls the following currents (give or take a few amps):
> >
> > RPM Current drawn (battery side current)
> > 1000 8 amps
> > 2000 15 amps
> > 3000 20 amps
> > 4000 40 amps
> >
> I'll say 4800 watts to spin up, that's 6.43 Hoursepower to freespin....
> Ok NOW we are getting somewheres......
>
>
> > These are BATTERY SIDE current readings, with NO load on the motor
> > except for the spinning aluminum flywheel/hub, clutch disc, and pressure
> > plate. I'm guessing that this is way too much current being pulled if
> > I'm supposed to see no more than 50 motor amps?
> >
> > I'll try to get my 400 amp shunt in the motor loop this weekend if I
> > have some spare cables around here with eyelets on them... otherwise
> > I'll have to order some more and wait...
> >
> > Last questions... If this is a motor problem, I'm assuming it could be
> > repaired (at a motor shop)? Are motors like this usually expensive to
> > repair?
>
> Oh oh!
> Well yea depending on the problems.
> Most of us racers can do a 9" incher rebuild. Shipping is a few hunder
> bucks, you can't use UPS because the motor is too heavy.
> A motor rebuild shop can help, ones that do fork truck and Golf cart
> rebuilds.
>
> And once you get it out... again.... Many on this list can lead you through
> testing and repair it it's simple bolt and unbolt stuff.
--- End Message ---
--- Begin Message ---
After reading James response it reminded me why we have fuses. If your
controller jams on high even 2 seconds would feel like an eternity. What
ratio for catastrophic failure and quick release would be safest? Also
after reading James response I am going to buy a fuse. Winning a Darwin
award is not the way I want to go out. Just driving a MC is dangerous
enough. The fuse I have is a LECTRA 400 amp. It blew quite quickly when I
put one side of the pack to the other and turned on the contactor. The
problem is that it is a specialty fuse and now I need to find something that
will fit the fuse compartment. Anyone have some of those 400 amp Lectra
fuses? Lawrence Rhodes.......
----- Original Message -----
From: "James Massey" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Saturday, December 04, 2004 2:58 PM
Subject: Re: Make your own fuse.
At 01:50 PM 4/12/04 -0800, Lawrence Rhodes wrote:
Is there some where that lists the capacity of copper wire or strips and
their use as a fuse. This might be dangerous but a 1/16 inch thick by 1/8
inch side piece of copper aught to be a good fuse for 48v 400 amps.
Hi Lawrence (and all)
Good quality fuses are made with silver down the middle, in a silicon-sand
filled ceramic tube for higher rupturing capacity. These are what should
be used for higher voltage EV traction pack use.
Automotive fuses are copper or copper-composite, and we've all seen the
'splat' in an automotive fuse at 12V when they have blown. Due to the low
voltage this is not a problem.
At 48V you are starting to be in a grey area of what is needed. One of the
problems with sizing fuses is the time that they take to blow at a given
current. For example, off a HRC fuse chart that I have, your fuse size
selected will depend on the length of time the maximum load is going to be
present.
400A 0.01 second, 35A fuse
400A 1 second, 80A fuse
400A 10 seconds, 100A fuse
400A 100 seconds, 150A fuse
400A 1000 seconds, 300A fuse
A 400A fuse can carry 400A indefinately.
So without knowing what your 400A time spec is, and your average current,
the size to fuse-open the piece of copper is unknown.
What I'd reccommend if you really want to try this, is to follow the
pattern that some forklifts use, copper sheet, cut similar to:
_____ _____
| | | |
| O ========= O |
|_____| |_____|
And mounted between two studs, with the molten copper able to fall away
onto something that does not matter (I'd use ceramic or cement sheet, an
inch or more away).
The width of the middle bit is the unknown, I'd make it what you think is
too small, and if it fails, go bigger. If it doesn't fail, and doesn't
heat discolour after a maximum-normal-current trial, maybe you have it too
big to do its job.
Regards
James Massey
Launceston, Tasmania, Australia.
--- End Message ---
--- Begin Message ---
I think I have my Lectra geared too high. I have the stock tires. 54 back
and 16 tooth front sprocket. I thought this would give me 45mph and still
be able to climb hills. It doesn feel as good off the line as the A89 with
a 12 tooth but it seems to keep pulling better as speed goes up. Not sure
I did the right thing. I don't want to burn up the motor by lugging it.
The bike now weighs around 700 pounds with a 250 pound rider. Lawrence
Rhodes.
--- End Message ---
--- Begin Message ---
At 04:59 PM 4/12/04 -0800, Lawrence Rhodes wrote:
After reading James response it reminded me why we have fuses. If your
controller jams on high even 2 seconds would feel like an eternity. What
ratio for catastrophic failure and quick release would be safest? Also
after reading James response I am going to buy a fuse. Winning a Darwin
award is not the way I want to go out. Just driving a MC is dangerous
enough. The fuse I have is a LECTRA 400 amp. It blew quite quickly when
I put one side of the pack to the other and turned on the contactor. The
problem is that it is a specialty fuse and now I need to find something
that will fit the fuse compartment. Anyone have some of those 400 amp
Lectra fuses? Lawrence Rhodes.......
Hi Lawrence
Presumably you still have the old fuse? If you share with us:
- any/all manufactures' markings
- body diameter
- body length
- end fitting or overall length
- end fitting holes/slots (diameter)
- inline or offset of the ends
a match may be determined.
Alternatively the internal dimensions of the fuse compartment, bolt spacing
etc.
Do you have an ammeter in the vehicle and so know the maximum current draw
under normal conditions?
Regards
James
--- End Message ---
--- Begin Message ---
You might want to look for an inductive ammeter for checking starter
current .
I have one from SnapOn and I dont think it was very much. The accuracy
is very general though it is basically a two inch gauge type ammeter
without any wire connections. and the divisions are marked only every
100amps.
Mike G.
TiM M wrote:
Does anyone know of a cheap DC amp clamp meter? Cheap
being in the $50 range. It seems most of the cheap amp
clamps I've seen are AC only, the DC ones I've found
are in the $180 and up range. I'm looking for a way to
verify my shunt and meter readings without breaking
the bank.
Thanks,
TiM
__________________________________
Do you Yahoo!?
Yahoo! Mail - 250MB free storage. Do more. Manage less.
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--- End Message ---
--- Begin Message ---
Just thought you might be interested,
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=3858180149&ssPageName=STRK:MESE:IT
Item 3858180149 on Ebay, a Brushless DC motor with
integrated control, rated at 1HP continuous.
Rod
--- End Message ---
--- Begin Message ---
.
What I'd reccommend if you really want to try this, is to follow the
pattern that some forklifts use, copper sheet, cut similar to
_____ _____
| | |
| O ========= O |
|_____| |_____|
And mounted between two studs, with the molten copper able to fall
away onto something that does not matter (I'd use ceramic or cement
sheet, an inch or more away).
Sorry about the picture mutilation;)
If you try this please carry a spare the cars I used to work on had a
fuse like this for the cooling fan they would fail from the changes in
the temperature from the surroundings ( metal fatigue ) more often than
from over current.
Mike G.
--- End Message ---
--- Begin Message ---
Madman,
I enjoyed your comments on the timeslip. That was a great race,
very close and exciting. You should have seen my EV grin fade,
then switch to pure astonishment as we approached the finish!
> > Range Dude, not power.
I don't claim my batteries to deliver any more than the normal
amount of capacity, but my power usage is indeed unbelievably
low. I just report the numbers I get from the E-meter. I have no
reason to doubt the accuracy of those numbers because other
measurements seem to agree, like motor heat. The other day I
drove to a neighboring town, 10 miles away. The first half was
stop and go city driving, then freeway for the 2nd half. I used just
a hair over 8 Ah for the trip and then took the motor's temperature
with my hand. After the 10 miles I would estimate that the motor
was at right around 100 degrees, give or take a couple deg. I think
that most of that heating was during the last half of the drive, after a
5 mile trip across town, it'll still be stone cold.
> Stuff my Raptor 1200 in that thing, and dial in about 5 Deg more brush
> timing, and you would be a hand full of seconds faster.
That's for sure!
> Six years ago..... I am feeling OLD.......So is Goldie...
Like the Rolling Stones said "What a draaag it is getting old"
It's happing to me too.....
John
--- End Message ---
--- Begin Message ---
Joe Smalley wrote,
> To make things fair, use a kWh meter instead of an emeter. It is older and
> does not have any of the fancy stuff on it.
I did a quick google search and didn't find the meter your were talking
about. Some more information here is that I wanted to leave the battery
charger out of the test, I just want to know how many wh/mile it takes to go
the 10 mile route. The challenge is to get the club members to make there
car more efficient with better tires, alignment, trans oil, rear end oil and
fixing dragging brakes.
> Keep a text file of the serial output as proof of which stoplights were
> green and to verify STOP signs were observed. This can also be used to
prove
> how long it took to drive the route.
This would be good info. it will also be interesting to see if one of the
other club members can drive the car to increase efficiency with driving
style.
Jeff Shanab wrote,
> Place a disqualification rule for people exceeding recommended tire
> pressure, checked at end of run? (have a witness?)
Good point, nobody can run more than the max tire pressure printed on the
side of the tire.
All great ideas keep them coming.
--- End Message ---
--- Begin Message ---
Hello all:
It has been quite a while since I've written to the list and I've
"lurked" only sporadically but in the past I have found the folks here
to be an amazing resource. Relying heavily on the experience of the
people here, I converted a Honda Del Sol in '98 and the time has again
come for me to throw out a few questions.
Work required me to bounce around the world for about a year and a
half and in that time, the car sat in the garage, basically ignored.
I've just finished putting in a fresh set of batteries (24 optima
yellowtops) and it seems that I"ve got a bad BattPro equalizer. It
releases a bit of magic smoke whenever connected to a battery. So, a
few questions:
1) Is there any place that sells these? I see the Rudman regs and they
look great but, for consistency and space concerns, I'd be interested
in just replacing the one BattPro. (Anybody have any clue about what
would cause one of these to just "go bad")
2) In resetting my E-meter, I've forgotten how to calculate the
Amp-hour capacity for this kind of application (144 VDC battery pack
with 12 buddied pairs of Optima yellow-tops). Anybody know what the
Amp-hour capacity would be or how to calculate this kind of
parallel/serial arrangement?
3) How often should the brushes on a 9" Advanced DC motor be changed?
I, as always, appreciate any help anyone can offer.
Thanks,
Scott Trowbridge
--- End Message ---
--- Begin Message ---
You might consider a Weight class and Cross Section Perimeter combination.
That way a very small car might be compared to a large motorcycle.
Weight is measured with driver and cargo as tested. It defines how much mass
is being accelerated during the test.
Cross Section Perimeter is measured at the fattest part of the vehicle. It
is intended to measure the largest factor in the wind loading loss factor.
By doing the record keeping with these numbers, it will be easier to compare
between unlike but similar vehicles.
Joe Smalley
Rural Kitsap County WA
Fiesta 48 volts
NEDRA 48 volt street conversion record holder
[EMAIL PROTECTED]
----- Original Message -----
From: "Jeff Shanab" <[EMAIL PROTECTED]>
To: "EVlist" <[EMAIL PROTECTED]>
Sent: Saturday, December 04, 2004 4:46 PM
Subject: Re: kWh/mile challenge
> Place a disqualification rule for people exceeding recommended tire
> pressure, checked at end of run? (have a witness?)
> divide into classes
> A430 Aero 4 wheel 30psi max
> A450 Aero 50 psi max
> S430 sedan 4 wheel 30psi max
> S450
> T430 truck
> T450
> M2 motorcycle
> M3 motorcycle + sidecar
>
> Even if a competiition is not held this kind of info would be invaluable
> for helping design and diagnose. If 10 people with 120V rabbits are
> getting 200 wh/mile and you are getting 300 in yours, you might suspect
> something is up.
>
--- End Message ---
--- Begin Message ---
I didn't mind the bipolar part. 25mA is "max" according to the
datasheet. I can throw together a 555 charge-pump inverter for that,
since I'm including other logic components that run at 5VDC, two simple
voltage tripplers can provide the +-15 it requires.
Seth Allen wrote:
They need a bipolar supply, and if they are like other LEMs, probably
need a few hundred milliamps worth for a current output. 25 mA might
be quiescent current, you will want to check the datasheet.
Typically better frequency response than Allegro parts, a more robust
output, but cost more and need a bipolar supply. Nice if you are
driving noisy low inductance motors where the response of the current
transducer needs to be fast so you can actually catch overcurrent trips.
Seth
On Dec 4, 2004, at 2:34 PM, Eric Poulsen wrote:
I bought two 400ADC current transducers on Ebay for about $20 (for
both). They operate on (I think) 12V, and output -4 to 4 VDC,
corresponding to -400 to + 400 ADC. The only problem is that
they're the pass-through type (gotta put wire through the hoop, not
clamp-on), and power it, and read the current w/ a meter.
In fact, it would appear the very same person is selling two more:
http://cgi.ebay.com/ws/eBayISAPI.dll?
ViewItem&category=7288&item=3856605920&rd=1
Dirt cheap if you don't mind a little wiring.
TiM M wrote:
Does anyone know of a cheap DC amp clamp meter? Cheap
being in the $50 range. It seems most of the cheap amp
clamps I've seen are AC only, the DC ones I've found
are in the $180 and up range. I'm looking for a way to
verify my shunt and meter readings without breaking
the bank.
Thanks,
TiM
__________________________________ Do you Yahoo!? Yahoo! Mail -
250MB free storage. Do more. Manage less.
http://info.mail.yahoo.com/mail_250
--- End Message ---
--- Begin Message ---
Don't forget tires naturally warm and pressure goes up as you drive.
A clever competitor could pack his tires in ice, put some water in
the tires, pass an initial check, and have the pressure "naturally"
increase as the car was driven. A competitor with an electrified
Humvee could use the while-driving tire pumps. :)
Maybe I missed a post, is this a safety worry? Since any competitor
can easily pump up the tires, I wouldn't see it as an unfair
advantage, why even worry about tire pressure?
--- Richard Furniss <[EMAIL PROTECTED]> wrote:
...
> Jeff Shanab wrote,
> > Place a disqualification rule for people exceeding recommended
> tire
> > pressure, checked at end of run? (have a witness?)
>
> Good point, nobody can run more than the max tire pressure printed
> on the
> side of the tire.
>
> All great ideas keep them coming.
> ...
...
=====
__________________________________
Do you Yahoo!?
Yahoo! Mail - 250MB free storage. Do more. Manage less.
http://info.mail.yahoo.com/mail_250
--- End Message ---
--- Begin Message ---
A couple of note worthy items at the Monster charger larBorotry
Yes Dorthy you can STUFF 20,971 watts of charge power into 13 Exide Orbital
XCD34, and not blow them up....And this is definatly not Kansas any more.
Joe and I clocked 111.54 amps at 188 volts into 13 Orbs.
No smoke, acid fumes, vented H2, nothing just a healthy transformer humm, and
both of us with our eyes glued to the Laptop control screen.
The Analog fast Reg controlled pull back went well, a little surging, that did
not dim the lights...
We are stepping up to 228 volts, with 19 Orbs. One was weak, and I chose to
take it out of the string since it was really causing the rest of the regs to
get hammered.
It was clearly marked .25Kw . Just light enough in a pack average of .30 to .32
Kwhr, that it really did cause issues. So Even when I ran it on the inverter
charger, it came up short of a full load.
EV trash talk
One interconnect short of a full pack.
One Reg lite
You just don't equalize today.. do Ya!
The Guys at the HOOD Canal Brewery are calling me the Wizz.
I have yet to come in for a beer with Arc Flash sunburn yet....
--- End Message ---
--- Begin Message ---
One way to measure the motor amps that I haven't seen yet , is to take one
of the motor wires , and run a known amperage through it like form a battery
charger , then take a voltage reading from one end of the wire to the other.
Now you are using the motor cable as a shunt, . I use my DMM which will read
10 amps to see how many amps the charger is putting out, if it says 5 amp
and I then measured a 5 mv voltage drop on the cable I can then tell ABOUT
how many amps are going through the wire by the voltage drop. so in the
above if a 100mv was read then 100 amps would be flowing. If you take an old
rpm meter and take the insides out they make nice amp meters . You can tap
in on the cable by a small cut and pulling out a few strands to make the
meter numbers line up the way you want . I set mine up so full scale is max
and just do the math./ / .
steve clunn
--- End Message ---
--- Begin Message ---
> Jeff Shanab wrote,
> > Place a disqualification rule for people exceeding recommended tire
> > pressure, checked at end of run? (have a witness?)
>
> Good point, nobody can run more than the max tire pressure printed on the
> side of the tire.
>
> All great ideas keep them coming.
What about musuring the amount of electirce to recharge the cars after the
run , could us the kw meter on your house and just trun off everthing else ,
or have one of these meters set up for just charging , .>
--- End Message ---
--- Begin Message ---
I bought one on eBay for around $10 once. I think it was from
the guy offering item 3813489303 currently.
It works ok for rough measurements. One drawback is it needs to
be held in a vertical position, otherwise the measurement will
be inaccurate by a significant amount.
Markus
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] On Behalf Of M.G.
> Sent: Samstag, 4. Dezember 2004 22:07
> To: [EMAIL PROTECTED]
> Subject: Re: DC clamp meter recomendation
>
>
> You might want to look for an inductive ammeter for
> checking starter
> current .
> I have one from SnapOn and I dont think it was very much. The
> accuracy
> is very general though it is basically a two inch gauge type ammeter
> without any wire connections. and the divisions are marked only every
> 100amps.
> Mike G.
>
> TiM M wrote:
>
> >Does anyone know of a cheap DC amp clamp meter? Cheap
> >being in the $50 range. It seems most of the cheap amp
> >clamps I've seen are AC only, the DC ones I've found
> >are in the $180 and up range. I'm looking for a way to
> >verify my shunt and meter readings without breaking
> >the bank.
> >
> >Thanks,
> >
> >TiM
> >
> >
> >
> >__________________________________
> >Do you Yahoo!?
> >Yahoo! Mail - 250MB free storage. Do more. Manage less.
> >http://info.mail.yahoo.com/mail_250
> >
> >
> >
> >
>
--- End Message ---
--- Begin Message ---
LOL, maybe I will use that tip to hold the throphy for awhile;-) but
seriously we do have a lot of very very clever club members after all they
do drive EV's, but between jobs, honeydews, finding stinkers and decorating
our cars for Christmas I don't think anyone has time for cheating, were just
not that competitive.
The idea here is that during our monthly EV meeting we can connect something
(meter) and the car can go on a quick test drive, it has to be very easy and
fun.
David Dymaxion wrote,
> Don't forget tires naturally warm and pressure goes up as you drive.
> A clever competitor could pack his tires in ice, put some water in
> the tires, pass an initial check, and have the pressure "naturally"
> increase as the car was driven. A competitor with an electrified
> Humvee could use the while-driving tire pumps. :)
>
> Maybe I missed a post, is this a safety worry? Since any competitor
> can easily pump up the tires, I wouldn't see it as an unfair
> advantage, why even worry about tire pressure?
>
--- End Message ---
--- Begin Message ---
Steve Clunn wrote,
> What about musuring the amount of electirce to recharge the cars after the
> run , could us the kw meter on your house and just trun off everthing else
,
> or have one of these meters set up for just charging , .>
You have a idea here, charging is so messy, the health of the battery pack
effects the amount of kWh you put back into the pack, but maybe we can
measure the efficiency of the charger (power in to power out) but doesn't
efficiency change over the charge cycle?
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Joe Smalley wrote,
>> To make things fair, use a kWh meter instead of an emeter.
>> It is older and does not have any of the fancy stuff on it.
Richard Furniss wrote:
> I did a quick google search and didn't find the meter your were
> talking about.
The KWH-meter was the predecessor of the E-meter, and was also made by
Cruising Equipment. I had one in my ComutaVan. I actually preferred it
in some ways to the E-meter; it only displayed Volts, Amps, or KWH
(selected with a front-panel 3-position switch). No Peukert or other
corrections; just the true data. No prescaler needed; it just read all
the way to 199.9v and +/-512 amps. LCD display with backlight; *much*
lower power consumption! Serial port was standard (not an option). About
the same size as an E-meter, but a square case, mounted by a screw in
each corner.
Note that Cruising Equipment is no more. They were bought out by Heart
Interface, who re-named the E-meter the "Link 10". Heart was in turn
bought out by Xantrex. And now Xantrex is discontinuiong the E-meter.
Its replacement is geared strictly for 12v mass-market consumer use; no
more high voltage or high current EV models.
On your efficiency race, I think you are falling into the trap of making
it too complicated. I would suggest going the opposite way; ENCOURAGE
creative and outside-the-box solutions!
For instance, if they can legally drive it, they can use it in your
economy run. Let the State Patrol determine what qualifies (maybe get an
off-duty officer to do your inspection).
Just define the starting and ending points, and a maximum time to get
there. Let them pick the route and the speed. If they can drive straight
cross-country at 5 mph, or the back roads at 20 mph, or take the freeway
at 50 mph, fine!
All you should need is a cheap analog data acquisition module to measure
battery volts and amps, an inexpensive GPS receiver, and a laptop PC.
Use a simple program to log volts, amps, time, and position. Figure out
from that who got the best efficiency.
This setup can be readily duplicated for as many cars as are in the
race. The laptop can be borrowed, the data acquisition module (with a
shunt) around $100, and about the same for a GPS receiver.
--
"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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Steve Clunn wrote:
> One way to measure the motor amps that I haven't seen yet, is to
> take one of the motor wires, and run a known amperage through it
> like from a battery charger, then take a voltage reading from one
> end of the wire to the other. Now you are using the motor cable
> as a shunt.
Yes; this works. The main drawback is that copper has a temperature
coefficient, so accuracy depends on wire temperature.
Also, you have to be careful how you make your connections to the wire.
You need to connect directly to the wire itself, not just add a wire to
the terminal at the ends. This is called a 4-wire connection, and is
what real shunts use.
Another related trick is to use a series motor's field winding as your
shunt. It is a higher resistance, so you get a larger voltage. This
makes it easier to measure with a simple voltmeter.
For example, my old ComutaVan's GE motor specified a field resistance of
0.0038 ohms +/-0.0004. That's a 1.9v drop at 500a; convenient for
reading with a digital multimeter on its 2v scale. I actually had an
analog meter with a series resistor adjusted to make it read 500a
full-scale.
Note: This was with a contactor controller. Don't try this with a PWM
controller! The DC voltage across the field is low, but the peak-to-peak
AC voltage is nearly the full pack voltage! You'll blow a digital meter
unless you add a very drastic filter to remove the AC component!
--
"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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Markus L wrote:
> I bought one on eBay for around $10 once. I think it was from
> the guy offering item 3813489303 currently.
>
> It works ok for rough measurements. One drawback is it needs to
> be held in a vertical position, otherwise the measurement will
> be inaccurate by a significant amount.
Yep! This type of meter can range from $1.98 (you'll find them in cheap
battery charger) to $99 (typically military surplus ones produced around
WW2). Their accuracy is basically determined by how well they are made,
which of course reflects in the price.
--
"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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