EV Digest 6513
Topics covered in this issue include:
1) Re: Better Data Logging Options?
by Lee Hart <[EMAIL PROTECTED]>
2) Re: Better Data Logging Options?
by john fisher <[EMAIL PROTECTED]>
3) Mick's answer to Lee Hart about BattEQ test
by "Mick Abraham" <[EMAIL PROTECTED]>
4) Re: Better Data Logging Options?
by "ProEV" <[EMAIL PROTECTED]>
5) New England EAA Meeting
by <[EMAIL PROTECTED]>
6) Re: Measuring Cable Resistance
by "Roland Wiench" <[EMAIL PROTECTED]>
7) Re: Best way to run battery cables
by Matt Milliron <[EMAIL PROTECTED]>
8) Re: My next EV project, or Paul goes Datsun
by "Lawrence Rhodes" <[EMAIL PROTECTED]>
9) cordless 36V equipment again
by john fisher <[EMAIL PROTECTED]>
10) Economics of balancing amps (was: Mick's answer to Lee Hart
about BattEQ test)
by Bill Dube <[EMAIL PROTECTED]>
11) Re: Better Data Logging Options?
by Mark Brueggemann <[EMAIL PROTECTED]>
12) RE: Prius OEM Tires
by Mark Brueggemann <[EMAIL PROTECTED]>
13) Re: cordless 36V equipment again
by "Dmitri" <[EMAIL PROTECTED]>
14) RE: Better Data Logging Options?
by "Roger Stockton" <[EMAIL PROTECTED]>
15) Re: PFC 20 configured- now what?
by "Rich Rudman" <[EMAIL PROTECTED]>
16) RE: My next EV project, or Paul goes Datsun
by "Pestka, Dennis J" <[EMAIL PROTECTED]>
17) Re: My next EV project, or Paul goes Datsun
by Lee Hart <[EMAIL PROTECTED]>
18) Re: electric power newbie
by "garyH" <[EMAIL PROTECTED]>
19) RE: Better Data Logging Options?
by Mike Chancey <[EMAIL PROTECTED]>
20) EVs in Chicagoland
by "Matt Kenigson" <[EMAIL PROTECTED]>
21) Re: Better Data Logging Options?
by "Osmo S." <[EMAIL PROTECTED]>
22) LRR tire comparision using Prius was Re: My next EV project, or Paul goes
Datsun
by "ProEV" <[EMAIL PROTECTED]>
--- Begin Message ---
Mark Brueggemann wrote:
--- Lee Hart <[EMAIL PROTECTED]> wrote:
Oh, for Pete's sake... my E-meter data logger BASIC
program started life on a Radio Shack model 100 laptop,
You're comparing apples and carrots, Lee. I've also written
simple data acquisition in BASIC, and run them from minimal
hardware. Just thought I'd offer the option of something
a bit more substantial than just number gathering, parsing
and saving to a file. I do LabView for a living, and while
it wouldn't even run on a P75 I've run it on sub 1GHz machines,
which anymore are throwaways. Thus, the modern equivalent of
a Model 100.
All I'm saying is that logging data from an E-meter is a trivial
application. You don't need a Pentium, Windows, and Labview to do it. In
fact, doing it with all that "stuff" is likely to complicate the
problem, and make it *less* likely that you will do it.
--
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 ---
Mark ( or anybody) have you run across an Open Source version of LabView? I understand it now runs on linux (probably in
WINE) but its pricey. Most of us need a much simpler solution anyway, like a VB package on the W32 side or some python
on the *ix side. Come to think of it, this would be a pretty good use of the OOness of Ruby too.
Maybe the robotics guys have something...
Mark Brueggemann wrote:
--....
Along with the overhead of having to run Winblows/Linux and
LabView you gain a huge processing and I/O capability.
--- End Message ---
--- Begin Message ---
Lee Hart said:
"Start with two batteries at different states of charge. Connect them
directly in parallel -- they instantly go to the same voltage!"
Mick says: Check. The paralleled batteries instantly display an average
voltage. There is still a subtle delta-v, however, and that drives energy
movement until the batteries match. The current drops, the delta-v drops and
the battery differences approach zero. This does take time but eventually
results in near perfect equalization. The battery differences cannot vanish
unless the amperage transfer and the delta-v also vanish.
Once the batteries "settle out at the same state of charge" (to use Lee's
phrase), one battery is no longer trying to finish charge the other one.
Lee's hypothetical paralleled batteries would then share any
charge/discharge energy evenly, and there will never be a need to move x
number of amp-hours from one paralleled battery to the other.
If you clip a load onto the terminals of one battery which is parallel with
another, its voltage drops slightly compared to the other one, but the
difference can never become very great. As soon as the delta-v increases
energy moves through the parallel cables so that a state of charge
difference does not develop and no subsequent amp hour restoration is
needed. A BattEQ equipped series string behaves much the same as if the
batteries were in parallel, provided that the balancer is properly sized for
the application.
Lee said: "It only takes a small amount of force to keep something balanced
that is already almost perfectly balanced."
Mick says: The word "force" is very appropriate. Instead of waiting until
big "state of charge" differences have developed, BattEQ applies continual
force which scales up as needed to prevent SOC differences from occurring.
The PowerCheq(TM) product is similar in this regard, but the biggest
PowerCheq can only pump in the same power range as the smallest BattEQ
devices. Two amps of balancing current is fine for relatively small
batteries, but drive packs for golf carts or bigger would require the bigger
BattEQ units.
Lee said:
"For batteries that are well matched, or that aren't used much, you'll
have enough time for a low balance current to work." He later said: "...when
there are extenuating circumstances...the number of amphours needed to
restore balance gets larger. That's where higher power balancers like my
battery balancer come into play."
Mick says: Please do not equate BattEQ with "low balance current" and please
do not categorically state that other solutions are "higher power". I have
BattEQ units in stock which can pump 16 amps out from each channel
continuously. This can be verified by those who take the trouble. If that's
not enough, additional units could be added in parallel. Even with a big
balancer, the current goes no higher than that required to maintain balance.
As soon as one monobloc tries to outperform or under perform, the group will
receive "energy discipline" which scales up or down with the delta-v. With
unruly batteries, the balance current will ramp up until things realign or
until the design limit of the balancer is reached.
Even when the battery is being recharged, BattEQ does not burn off excess
energy through heat dissipation. Instead it pumps that into the monoblocs
that need it. With BattEQ one cannot detect high power in the form of hot
dissipaters atop a battery bank, because instead the power is going into the
weak monoblocs to improve the balancing process.
Lee said: "For an EV, your "daily drive" will produce some degree of
imbalance. This can be expressed by how many amphours difference is
required to bring each battery back to the same state of charge. Then, you
need a balancing system that can produce this much charge differential per
day."
Mick says: Lee's description above would be correct only if the balancing
system is deployed after the daily drive is complete. However, because
BattEQ works 24/7 the battery doesn't develop imbalances to be corrected
later with "10's of amp hours". Since BattEQ pumps energy in real time to
maintain alignment, the balancing game becomes one of instantaneous energy
transfer instead of amp-hour restoration after the fact. So long as the
instantaneous energy transfer is sufficient, there's never a need to correct
an accumulated state of charge deficit.
Mick Abraham
www.abrahamsolar.com
--- End Message ---
--- Begin Message ---
Hi Osmo,
Could Labview be used as a BMS for lithium cells?
Yes. We have written a program in Labview to control the BMS on our Kokam
batteries. We designed the BMS using Lee Hart's Battery Balancer
(http://www.geocities.com/sorefeets/balancerland/) concept but using some
off the shelf DAQ and relay control boards from EECI (www.EECI.com).
Labview is very expensive but makes modifying both the interface and the
operating of the software, quick and easy. It is a great program.
Cliff
www.ProEV.com
--- End Message ---
--- Begin Message ---
Hi EVerybody;
Rapidly approaching the second Sat of the month! So...... come on out to my
place in Killingworth ,CT, for the festivities, oh, around 2pm or so. Plenty
of high class, pricy, electricity to plugitin if you come in an EV. 120/240
volts or so.
Saying"Seeya" and meaning it?
Bob
--- End Message ---
--- Begin Message ---
This is what I do about every 3 months when I equalize and clean my
batteries. I do a quick test with a multi meter set at the milliamp scale,
reading in parallel with each link, but the test leads are connected to the
battery post, not to the connector while the battery charger is set at about
10 amp.
Normally when I install new links, I use this method to torque all the
battery connections to about 0.01 ma each. After the first 5 miles you will
get a shrink back, where a connection could read as high as 0.1 ma amp. I
will re torque these connections to match all the others.
According to my electrical handbook, this is known as a connection shunt
test.
You could re torque all the battery connections while the charger is on, if
you are experience with hot line methods and tools required. To do it hot,
you need to cover the entire surface of the battery tops, except the one you
are working on with a certified electrical blankets rated for that voltage.
Also cover any expose metal parts of the vehicle and have a electrical
insulated floor. Do not wear any metal objects, belts, and wear insulated
boots.
Then you must use double insulated inch lb torque wrench. These are a
plastic handle cover with a rubber grip. I use a large 2 inch diameter foam
cover over these that slip down all the way to the socket end.
This is normally a four man operation working with high volt or two man with
voltages under 600 volts. One to do the test, one standing by to observed
and ready to open a disconnected switch.
Roland
----- Original Message -----
From: "Lee Hart" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Monday, March 05, 2007 10:25 AM
Subject: Re: Measuring Cable Resistance
> > --- In [EMAIL PROTECTED], "Bruce" <[EMAIL PROTECTED]> wrote:
> >> How exactly does one measure the resistance of battery cables?
> >> It is too small of an amount to measure with my common multimeter.
>
> Death to All Spammers wrote:
> > I don't know how to do it with a basic VOM, but it's done under load,
> > measuring voltage drop at a set amperage.
>
> You've got it right, you just didn't realize it!
>
> Run a known current through the cable (or connector, or motor winding,
> or anything else that has too low a resistance to measure directly).
> Your multimeter can tell you what this current is; most have a 10amp or
> 20amp scale. For example, you can get this current from a battery
> charger charging a dead battery, or from a power supply with a big load
> resistor.
>
> Use your multimeter to measure the voltage drop across the cable (or
> whatever).
>
> Use Ohm's law to calculate its resistance. For example, suppose the
> current is 15 amps, and the voltage drop across the cable is 0.1 volts.
> Then the resistance of the cable R = V/I = 0.1v / 15a = 0.0067 ohms (6.7
> milliohms).
>
> --
> 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 ---
> Two considerations I can think of: physical protection and losses. What do
> folks generally do >when running battery cables from the boxes (on the rear
> of a small pickup in this case) up to the >controller/motor area? Conduit?
> Cable-tied together running along a frame rail? Some other >kind of device?
> I'd appreciate any/all opinions, advice, etc.
I covered mine with a piece of soaker hose made from old tires. Then cable
tied them together. I plan to cover the cables from the controller to the
motor with metal (aluminum) tape that I found. I hope to keep any radio static
down.
Matt Milliron
--- End Message ---
--- Begin Message ---
The later Datsuns were engineered much closer to spec. The vehicles from
the 60's were a different breed. The Z car of your vintage is 6 years
removed from the coveted orginal 240's which were EVen lighter than your
car. There is very little in common between your car and the vintage from
10 years previous except rear wheel drive. They were over built but the
motors were a weak point relatively(better than the British models) and
parts became a problem. The drive train and bodies are very tough. It
might EVen be possible to replace the rear seat with a practical battery box
with a modified bench seat over it. Lawrence Rhodes.....
> Paul,
> Perhaps I can weigh in with my 17 years experience with a 1977 Datsun Z.
--- End Message ---
--- Begin Message ---
I am really interested in the thread on using the dewalt cordless 36 V lithium setup. In my case, it would be for a 3/4
wheel bicycle or light MC or go-kart prototype. Just something to learn on.
Since I am not an EE, the battery management issues are daunting, and the opportunity to use off-the shelf commercial
stuff is very attractive. I don't mind the thought of having a row of chargers in my garage.
question: how do you make a battery pack out of multiple battery units? say 72
V and multiple units deep.
In other words, does making these things into a battery pack defeat the whole
off-the-shelf approach?
TIA
John
--- End Message ---
--- Begin Message ---
It is "penny wise and pound foolish" to implement a continuous
balancing system that pushes around a large number of amps. Once you
do the accounting, you discover that it costs you more than you save
if you push around much more than an amp with a continuous type BMS.
The key to this is that individual "bad" batteries in a pack don't
typically "fail" slowly, but rather quickly. Propping up a failing
battery by feeding it significant charge through the BMS increases
its life span just a few percent. When you compare the cost of the
earlier failed individual battery replacement, with the cost of
increasing the transfer amperage of the BMS, you discover you are
spending a lot of money to save a few pennies.
The BMS needs to cover the expected differences in charge efficiency
and self-discharge plus a reasonable margin. That's it. It also
should flag a weak battery, (like a "check engine" light) so you know
you'd better replace it soon.
It is different in an application where you cannot easily replace a
bad battery, like in a spacecraft, or a combat vehicle. However, a
daily driver EV is not that sort of application.
Bill Dube'
At 10:53 AM 3/5/2007, you wrote:
Lee Hart said:
"Start with two batteries at different states of charge. Connect them
directly in parallel -- they instantly go to the same voltage!"
Mick says: Check. The paralleled batteries instantly display an average
voltage. There is still a subtle delta-v, however, and that drives energy
movement until the batteries match. The current drops, the delta-v drops and
the battery differences approach zero. This does take time but eventually
results in near perfect equalization. The battery differences cannot vanish
unless the amperage transfer and the delta-v also vanish.
Once the batteries "settle out at the same state of charge" (to use Lee's
phrase), one battery is no longer trying to finish charge the other one.
Lee's hypothetical paralleled batteries would then share any
charge/discharge energy evenly, and there will never be a need to move x
number of amp-hours from one paralleled battery to the other.
If you clip a load onto the terminals of one battery which is parallel with
another, its voltage drops slightly compared to the other one, but the
difference can never become very great. As soon as the delta-v increases
energy moves through the parallel cables so that a state of charge
difference does not develop and no subsequent amp hour restoration is
needed. A BattEQ equipped series string behaves much the same as if the
batteries were in parallel, provided that the balancer is properly sized for
the application.
Lee said: "It only takes a small amount of force to keep something balanced
that is already almost perfectly balanced."
Mick says: The word "force" is very appropriate. Instead of waiting until
big "state of charge" differences have developed, BattEQ applies continual
force which scales up as needed to prevent SOC differences from occurring.
The PowerCheq(TM) product is similar in this regard, but the biggest
PowerCheq can only pump in the same power range as the smallest BattEQ
devices. Two amps of balancing current is fine for relatively small
batteries, but drive packs for golf carts or bigger would require the bigger
BattEQ units.
Lee said:
"For batteries that are well matched, or that aren't used much, you'll
have enough time for a low balance current to work." He later said: "...when
there are extenuating circumstances...the number of amphours needed to
restore balance gets larger. That's where higher power balancers like my
battery balancer come into play."
Mick says: Please do not equate BattEQ with "low balance current" and please
do not categorically state that other solutions are "higher power". I have
BattEQ units in stock which can pump 16 amps out from each channel
continuously. This can be verified by those who take the trouble. If that's
not enough, additional units could be added in parallel. Even with a big
balancer, the current goes no higher than that required to maintain balance.
As soon as one monobloc tries to outperform or under perform, the group will
receive "energy discipline" which scales up or down with the delta-v. With
unruly batteries, the balance current will ramp up until things realign or
until the design limit of the balancer is reached.
Even when the battery is being recharged, BattEQ does not burn off excess
energy through heat dissipation. Instead it pumps that into the monoblocs
that need it. With BattEQ one cannot detect high power in the form of hot
dissipaters atop a battery bank, because instead the power is going into the
weak monoblocs to improve the balancing process.
Lee said: "For an EV, your "daily drive" will produce some degree of
imbalance. This can be expressed by how many amphours difference is
required to bring each battery back to the same state of charge. Then, you
need a balancing system that can produce this much charge differential per
day."
Mick says: Lee's description above would be correct only if the balancing
system is deployed after the daily drive is complete. However, because
BattEQ works 24/7 the battery doesn't develop imbalances to be corrected
later with "10's of amp hours". Since BattEQ pumps energy in real time to
maintain alignment, the balancing game becomes one of instantaneous energy
transfer instead of amp-hour restoration after the fact. So long as the
instantaneous energy transfer is sufficient, there's never a need to correct
an accumulated state of charge deficit.
Mick Abraham
www.abrahamsolar.com
--- End Message ---
--- Begin Message ---
--- john fisher <[EMAIL PROTECTED]> wrote:
> have you run across an Open Source version of LabView?
None that I'm aware of.
> I understand it now runs on linux (probably in WINE)
There are native versions for Windoze, Linux and Mac.
> but its pricey.
Yes it is, but given it's breadth of application in an EV
environment it could be easily rationalized as part of the
equipment or development budget. For the cost of a BMS
it could not only perform BMS functions, but many others
both on and off the vehicle. In my case, the EV expenditures
(save batteries) are complete, so I view it as an accessory
to enhance it's operation and facilitate experimentation
that would be difficult if I had to first come up to speed on a
programming language, just so I could create applications,
and then begin my experiments. I just want to play, not
spend all my time coding and compiling.
> Most of us need a much simpler solution anyway,
Granted. What I find compelling is you don't need to be
a programmer to get a nice looking GUI, read/write I/O
and interface it to the world. But, you pay for that
convenience.
Mark "EV Basher" Brueggemann
Albuquerque, NM
S-10 EV
--- End Message ---
--- Begin Message ---
"jerryd" <[EMAIL PROTECTED]> wrote:
The Prius and now Insight are Bridgestone RE92 165-65's
"Shawn Waggoner, FLEAA" <[EMAIL PROTECTED]> wrote:
> My '07 Prius has Goodyear Integrity P185/65R15 tires on it
Thanks guys, that helped add a data point to my "tire collection".
Mark "EV Basher" Brueggemann
Albuquerque, NM
S-10 EV
--- End Message ---
--- Begin Message ---
You must open the pack and bypass the internal circuitry(BMS?) when putting
them in series for discharge, like for 72V. Otherwise, the DeWalt battery
circuitry will fry, according to somebody who tried this on the
Visforvoltage forum. Paralleling should also be done at the cell level, not
pack level as would be with these. So, it could be lots of trouble.
----- Original Message -----
From: "john fisher" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Monday, March 05, 2007 2:06 PM
Subject: cordless 36V equipment again
I am really interested in the thread on using the dewalt cordless 36 V
lithium setup. In my case, it would be for a 3/4 wheel bicycle or light MC
or go-kart prototype. Just something to learn on.
Since I am not an EE, the battery management issues are daunting, and the
opportunity to use off-the shelf commercial stuff is very attractive. I
don't mind the thought of having a row of chargers in my garage.
question: how do you make a battery pack out of multiple battery units?
say 72 V and multiple units deep.
In other words, does making these things into a battery pack defeat the
whole off-the-shelf approach?
TIA
John
--- End Message ---
--- Begin Message ---
Mike Chancey wrote:
> I forgot to mention, my repaired E-meter seems to output a slightly
> different data string than it used to. It used to look like this:
>
> 21224,-00.69,+003.1,172.0,-0005.0,-0008.3,+0004.9,255.0,5
>
> Now it looks like this:
>
> 33050,-00.44,+004.4,182.5,-0001.0,-0001.4,+0005.7,255.0,E,21
Mike, the alpha character is still the number of bars lit; it is numeric
normally and switches to alpha characters when the low-battery output is
active.
The last number is temperature in Degrees C.
>From the manual:
Time, KWhrs, Amps, Volts, Ahrs, Peukert Ahrs, Peukert Amps, Time
remaining,
Bar Graph state, Temperature (degrees C.)
The Bar Graph state is indicated by the following integers:
1<20%, 2<40%, 3<60%, 4<80%, 5<100%, 6 = Full (Charged Params met)
If the Low Battery Output is activated, the Bar Graph state is indicated
as:
A<20%, B<40%, C<60%, D<80%, E<100%, F = Full (Charged Params met)
Set F14 to OFF to disable the low-battery alarm feature if you don't
want it; otherwise set parameters F10-12 to configure its operation.
Set F16 to OFF to disable the external temperature sensor if you don't
have one. When F16 is ON, select F03 to view the sensed temperature in
degrees C; when F16 is OFF, set F03 to the desired battery temp (default
is 20C) for temperature compensation of the battery capacity (affects
bargraph and time remaining displays).
Regarding datalogging, like Lee, I also use a simple QuickBasic program
to log my E-Meter data. If didn't already know, QuickBasic 1.1 is free
and can be found online or on Win98 installation disks (it was
distributed, but not automatically installed). QuickBasic is about
273kB, and your logging program will be only a couple of kB, so you can
easily run everything from a 3.5" floppy. You can run QuickBasic in a
DOS/command prompt window, and windowed or not it can access any network
drive available.
Lee's program is good, but if you don't need the graphical display it
gets much simpler. If you don't bother with discarding data when values
haven't changed significantly, it gets trivially simple (main loop is
wait for E-Meter record on serial port, write to disk, write to screen,
check for key pressed and repeat if no key pressed). My logging app
maintains a 1-line summary at the top of the screen rather than Lee's
fancy graphs ;^) (after printing the new E-Meter record to the screen,
the screen scrolls up one line, then position the cursor at the top left
and over-write that line with the new summary line). I've been using an
old '286 laptop (12MHz?) with precious little harddisk space free, and
found that adding a simple counter to terminate the logfile after a set
number of seconds (E-Meter records) had elapsed (10hrs in my case) was a
simple way to keep the logfile from filling the disk if left running
overnight.
I prefer to keep every bit of data, just in case it is later useful
(logging every record makes plotting easier), but even so a typical
10-hour logfile is "only" about 1.6Mb and pkzips down to about 200kB for
transfer via 3.5" floppy to another machine for storage and Excel
processing. 10hrs is 36000 records, and Excel has a 32000 point limit
for graphs, so you could reduce the logfile size a bit by terminating it
automatically after 32000 records.
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
The charger will take it.
A PFC20 can draw 24.5 amps of grid.
Can your breaker take it??
Rich Rudamn
Manzanita Micro
----- Original Message -----
From: "Richard Acuti" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Saturday, March 03, 2007 2:43 PM
Subject: PFC 20 configured- now what?
> I spent an evening charging and tweaking my PFC 20 to the proper voltage
to
> charge my new batteries as well as the timer. The instructions have you
> setting the voltage at a very low rate of charge.
>
> The breaker the charger is plugged into is dedicated for the car.
According
> to the vendor, my batteries can be charged up to the 60 amp rate. If I
> understand correctly, the PFC 20 (without buck enhancement) is only
putting
> out 20 amps. Can I turn up the amperage knob now? How far? All the way?
>
> Thanks,
> Rich A.
> Maryland
>
> _________________________________________________________________
> Mortgage rates as low as 4.625% - Refinance $150,000 loan for $579 a
month.
> Intro*Terms
>
https://www2.nextag.com/goto.jsp?product=100000035&url=%2fst.jsp&tm=y&search=mortgage_text_links_88_h27f6&disc=y&vers=743&s=4056&p=5117
>
--- End Message ---
--- Begin Message ---
Paul;
It would look great sitting next to my 65 pickup.
I will keep an eye on your web site.
Still trying to decide a few things myself.
Dennis
Elsberry, MO
-----Original Message-----
From: Paul G. [mailto:[EMAIL PROTECTED]
Sent: Sunday, March 04, 2007 7:11 PM
To: [email protected]
Subject: My next EV project, or Paul goes Datsun
--- End Message ---
--- Begin Message ---
[EMAIL PROTECTED] wrote:
I wasn't aware the Prius used special tires. How do they differ
from tires on other cars?
They aren't all that special. But they did supply low rolling resistance
tires, optimized more for high miles per gallon at the expense of tire
life and cornering. Also, they are a higher load rating (and thus can be
inflated to higher pressures) than usual.
For example, our 2001 Prius came with Bridgestone Potenza RE92 175/65R14
tires, marked "extra load", 1107 lbs at 50 psi, and had a wear rating of
160. The standard Bridgestone Potenza 175/65R14 you get at a tire store
is rated 1047 lbs at 35 psi, and has a wear rating of 320. Using the
standard tire, you'd lose 2-3 mpg and about 240 lbs of load carrying
capacity, but they last about twice as long.
--
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 ---
Thank you Peter for your reply you have made things a lot clearer.
<So running the motor at under it's rated current is no problem,
running at OVER it's rated current can get you in trouble.>
I have tested the motor with 12V and then 24V being aware of its desire to
self destruct.I also had an ammeter connected to it which went to 110A when
I put load on the motor.Freewheeling it was 60A.So I'm figuring current is
related to load which is almost constant for my application.(no hills to
climb).
That is very interesting running it as a shunt motor.There is a smaller wire
coming out of the field coils for generator field excitement.Could you
explain how I would rewire for shunt use.
Cavitation is a concern for me because it would cause the motor to speed up
causing more cavitation etc.
Name Plate Details:
Westinghouse Elec and Manufacturing Co. (I guess that kinda dates it.1950's
I figure)
Mfr.serial no. AF44-945490
Type P-1
"for use with 24V systems"
also,drawing no.,and acceptance no.
thanks..........gary
----- Original Message -----
From: "Peter VanDerWal" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Monday, March 05, 2007 7:13 AM
Subject: Re: electric power newbie
The motor does have a intake for
external fan but being a starter generator I am a little worried that
continuous use as a motor may not be something it is capable of doing.
They are generally under continuous use when operating as a generator.
The difference between a motor and a generator is simply which direction
the energy is going.
However, from what I've read Air Craft starter/generators are typically
not very efficient. It's going to be turning a lot of your energy into
heat, so you need to get rid of the heat.
The guys that used to race E-boats would often dunk the whole motor in the
water after a race. You might want to keep that in mind as a method to
quickly cool down the motor if you do over heat it.
I
am
not well versed on controllers but my understanding is that they switch
off
and on to reduce voltage to motor as required.What happens to a motor
that
is too powerful for its application and is always being used at say 60%
load. If this were a 100V motor would it be continuously running on 60V
and
would this damage the motor ...Gary
Nope. Actually you can probably run your motor at MORE than the name
plate rating. The voltage rating on a motor is just one point on the
spectrum of voltages & currents that the motor can operate at.
Often motor manufacturers will take the EXACT same motor and put two
different rated voltages on it for two different customers.
There are basically two things that can damage a motor: getting it too
hot, and spinning too fast.
The current through a motor causes heat. As long as you can get rid of
the heat, no problem. The higher the current through the motor, the more
heat it generates. At some point the motor gets hotter than you can cool
it off. When this happens the motor starts to get hotter, and hotter.
Once it gets hot enough the insulation starts to melt/fry and then you get
shorts in the motor, and then the windings, etc. start to melt.
Now here's the bad news, the ammount of heat generated goes up as the
SQUARE of the current. Double the current and you get four times as much
heat. So running the motor at under it's rated current is no problem,
running at OVER it's rated current can get you in trouble. You can
generally do if for a short time (The motor has a lot of mass and takes a
while to heat up), but the higher the current, the less time you can do
this.
It's best to play it safe and stay under the rated current.
Now for the RPM. I'm not sure what kind of RPM these motors can take,
perhaps Lee will step in and give his opinion. But at a guess I'd say
it's probably 5,000 to 6,000 RPM.
Keep it under that, and you have no problem. Let it go over that and the
motor goes into self-disassembly mode. Not pretty. Motors aren't very
smart and I haven't seen one yet that can take itself apart in a manner
where it's easy to put it back together.
I believe your motor operates as a series wound motor in the starter mode,
and a shunt wound motor/generator in the generator mode.
If this is the case, then I'd run your motor as a shunt wound motor. It's
a lot easier to control (and the controllers are cheaper) plus you don't
have to worry about over-revving it so much. In fact you could probably
get away with using a cheap E-bike controller for controlling the field
voltage.
Can you post the manufacturer and part number from the motor? It would
make it a lot easier to suggest a method for controlling the motor. Post
everything that's on the name plate.
*******************
Series wound motors
*******************
For most motors the RPM is related to the voltage. Double the voltage and
you double the RPM. Series wound motors are a little different. The
voltage/RPM relationship is only true for a given load. Reduce (or
remove) the load and the RPMs go up. Power the motor up with it's rated
voltage and no load and it will happily try to spin up to near infinite
RPMs. Unfortunately, long before it gets to infinity, parts of the motor
will decide to relocate.
The moral here is not to power the motor up without a load unless you are
using very low voltage. With a low enough voltage the friction in the
motor is enough of a load to keep it from overspinning.
Of course the problem is: how low is "low" voltage. In your case I'd
probably start with 6 volts and see if it sounds like the motor is going
to spin too fast. With only 6 volts it will take the motor a bit to get
up to speed.
If it turns REALLY slowly, then you can probably get away with 12V.
If it starts to pick up speed and sounds like it's going to keep picking
up speed, then disconnect and try a lower voltage.
The above is just for testing. Once you have a prop connected, you
shouldn't have to worry about it as long as the prop is in the water.
Hmm, unless you start to cavitate. If that happens, and your voltage is
high enough, you might get into over-rev territory. I can't say for sure
since I'm not even close to playing a boating expert on TV.
----- Original Message -----
From: "Lee Hart" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Sunday, March 04, 2007 9:38 AM
Subject: Re: electric power newbie
[EMAIL PROTECTED] wrote:
I'm starting to build a small electric propulsion system . I
have a 24V Westinghouse aircraft starter-generator which were sold
by Princess Auto of Winnipeg at one time. It is 8 pole series
wound, around 3 Kw I believe, so should be ample power for my
application. I haven't been able to get any specs on this machine
so I'm not sure if its rated for continuous use or not. Does
anyone have any info for this motor?
You'll have to provide more information for us to be able to tell what
you
have. What does the nameplate on it say? What is its size and weight?
3kw is only about 3 horsepower; that's not much. OK for a golf cart or
small motorcycle, but not a car.
Most of these units are designed for continuous duty at high rpm, with a
very strong airflow for cooling.
I'm also not sure if drive will slow the motor down to the 900 or so
RPM it would like to run at. Maybe the controller will take care of
this.
A controller can make it run slower, but you also decrease power. If it
produces 3kw at full speed, it will only produce 1.5kw at half speed,
etc.
Is it possible to reverse this motor?
Yes, but they usually require some disassembly and internal wiring
changes.
--
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: 7.5.446 / Virus Database: 268.18.6/709 - Release Date: 3/3/2007
8:12 AM
--
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.
--
No virus found in this incoming message.
Checked by AVG Free Edition.
Version: 7.5.446 / Virus Database: 268.18.6/709 - Release Date: 3/3/2007
8:12 AM
--- End Message ---
--- Begin Message ---
Roger wrote:
Mike, the alpha character is still the number of bars lit; it is numeric
normally and switches to alpha characters when the low-battery output is
active.
<SNIP>
Thanks for the info. I wish Xantrex had bothered to include a copy
of the updated manual when they updated the meter. For some reason
it is no longer available as a download on their site. I have a bad
feeling they may be planning on dropping it from production.
Thanks,
Mike Chancey,
'88 Civic EV
Kansas City, Missouri
EV Photo Album at: http://evalbum.com
My Electric Car at: http://www.geocities.com/electric_honda
Mid-America EAA chapter at: http://maeaa.org
Join the EV List at: http://www.madkatz.com/ev/evlist.html
In medio stat virtus - Virtue is in the moderate, not the extreme
position. (Horace)
--- End Message ---
--- Begin Message ---
Howdy,
I see there are a bunch of EVs in the album around the Chicagoland
area. I'll be in Chicago for a meeting on Saturday. Is there anyone
who might want to get together and trade notes, chat about CURRENT
EVents? I'd love to see some more EVs, so I try to visit folks
whenever I travel. This time around, though, I prolly won't get a car
unless there's someone outside of a reasonable cab fare range that I'd
like to visit. Wish you could rent EVs in Chicago.
Anyway, anyone out there interested in getting together? You can
reply off-list.
Matt Kenigson
http://www.austinev.org/evalbum/882
--- End Message ---
--- Begin Message ---
Revealing my ignorance here... how does Labview differ from a
"normal" BMS like this Reap system:
http://tinyurl.com/2wmw2e
Labview is software-based while Reap is hardware? What are pros and
cons of both methods, particularly relating to safety issues? Which
one is more susceptible to failures?
kiitoksin,
Osmo
Mark Brueggemann kirjoitti 5.3.2007 kello 17.57:
--- "Osmo S." <[EMAIL PROTECTED]> wrote:
Could Labview be used as a BMS for lithium cells?
It can do whatever you can interface it to. If whatever your
doing can be read/controlled with a logic or analog signal,
it can be processed by LabView. Depending on the I/O method,
the overhead of the operating system, bus/processor speed
limitations and other processes executing at the same time there
can be latency issues but for most acquisition and control
processes that execute in the order of 1 microsecond or greater
it's pretty close to real time. You can bump that up if you're
willing to move to specialized I/O hardware.
Mark "EV Basher" Brueggemann
Albuquerque, NM
S-10 EV
--- End Message ---
--- Begin Message ---
Hi Mark,
Any idea what make/model the Prius tires are?
I just replaced my no longer made Goodyear Conquests
with Michelins's but it was a struggle to find anyone
that had any idea what LRR was or what the actual
tire spec's were. Would like a basis of comparison
agains the Prius tires.
I have done some casual MPG tire testing with a 2005 Prius. Though the
testing was done on a hybrid, I think that the confusion I encountered is
applicable to any EV kW-hr used per mile tests and choosing a LRR tire for
an EV.
The Prius came with Goodyear Integrity 185 / 65 R15 tires. There has been
some speculation that the exact tire the Prius come with is different from
the same named tire bought off the shelf. I am not sure what evidence this
rumor is based on but the standard Goodyear Integrity tires are rated as
only an 'average rolling resistance' tire.
I decided to replace the Goodyear's with a close match in size but a low
rolling resistance tire. Based on a Michelin tire engineer's recommendation,
I went with the Michelin Energy MXV4 S8 195 / 65 HR15. This tire was not
offered in a 185 so I went with the slightly wider 195. I looked
specifically for the HR15 rather than the VR15. The HR is rated to 51 PSI
maximum rather than the VR's 44 PSI.
The 2005 Prius was being driven the same route regularly and over a long
period of time so it was possible to get a pretty steady average. The route
was mainly 70 MPH highway and the Prius was getting 48 MPG with the tires at
40 PSI. Over time, same route, same driver, the mileage began to improve
reaching 50 MPG at 50,000 miles. As this point the tires were worn to the
point of needing replacement.
I put on the Michelins set to 35 PSI and the mileage dropped to 47 MPG. I
filled the tires to 50 PSI and the miles per gallon climbed back to our
orginal 48 MPG. Same as the stock new Integrity, 2 MPG less than the broken
in Integrity's.
I was confident that the driver, driving style, route had not changed. The
car was not tuned or changed when we switched tires. It would seem that the
Goodyears got better the more they were used and the Michelins were not any
better than the Goodyears but...
I did a quick spreadsheet to check how the change in tire circumference from
wear and slightly different tire sizes might be effecting our numbers. I
have posted the Excel spreadsheet at
http://www.proev.com/Misc/Prius05/Prius1.htm for anyone who wants to play
with it.
What I found was that the actual miles per gallon seems to have held pretty
steady as the tires wore but since the tire got smaller as the tread wore
away, the car reported that it had traveled more miles. Calculating for the
worn tire the recorded 50 MPG was closer to 48.8 MPG.
The Michelin have a slightly greater circumference, so that the 47 mpg
reading that we got at 35 PSI was equivalent to 48.4 MPG with new Goodyears.
And the 48 MPG with the Michelins at 50 PSI was equivalent to 49.4 MPG.
It is hard to have better than plus or minus 1 MPG confidence with this
casual testing. My best guess is that under these conditions, the Michelin
Energy MXV4 S8 195 / 65 HR15 at 50 PSI were worth somewhere between 0.5 to
1.5 MPG over the original Goodyear Integrity 185 / 65 R15 .
Cliff
www.ProEV.com
--- End Message ---
