EV Digest 6514
Topics covered in this issue include:
1) Re: Motor mods
by James Massey <[EMAIL PROTECTED]>
2) Re: Economics of balancing amps (was: Mick's answer to Lee Hart about
BattEQ ...
by [EMAIL PROTECTED]
3) Re: LRR tire comparision using Prius was Re: My next EV project,
or Paul goes Datsun
by "Peter VanDerWal" <[EMAIL PROTECTED]>
4) RE: Better Data Logging Options?
by "Dale Ulan" <[EMAIL PROTECTED]>
5) Re: Better Data Logging Options?
by john fisher <[EMAIL PROTECTED]>
6) Re: PIC help
by brian baumel <[EMAIL PROTECTED]>
7) Re: cordless 36V equipment again
by john fisher <[EMAIL PROTECTED]>
8) Re: Better Data Logging Options?
by john fisher <[EMAIL PROTECTED]>
9) Re: ZIF Recommendation
by Bill Dennis <[EMAIL PROTECTED]>
10) Re: ZIF Recommendation
by Lee Hart <[EMAIL PROTECTED]>
11) Re: electric power newbie
by "Peter VanDerWal" <[EMAIL PROTECTED]>
12) Re: Compressed air as battery?
by "Peter VanDerWal" <[EMAIL PROTECTED]>
13) Re: PIC help
by "FRED JEANETTE MERTENS" <[EMAIL PROTECTED]>
14) wheel hub motor
by KARSTEN GOPINATH <[EMAIL PROTECTED]>
15) Re: Measuring Cable Resistance
by "FRED JEANETTE MERTENS" <[EMAIL PROTECTED]>
16) Re: ZIF Recommendation
by Bill Dennis <[EMAIL PROTECTED]>
17) SCR's last orders
by [EMAIL PROTECTED]
18) Re: swamp cooled EV?
by <[EMAIL PROTECTED]>
19) Re: Compressed air as battery?
by GWMobile <[EMAIL PROTECTED]>
--- Begin Message ---
G'day Jeff, Jim and All
At 09:01 AM 5/03/07 -0800, Jeff wrote:
Hi Jim,
I had inquired of James if these were MKZ type motors. Never got a reply.
Sorry Jeff, missed that message. MKZ-4003S motors.
The MKZ was a problem child design. It was field swamped. Way, way too
much. So the field coils tended to fry. Too high I squared R. The
motor was really not too small for that lift truck. Replacement design,
MKN type did just fine. MKN was same motor design as MKZ except a lot
less effective field strength (turns) and lower I squared R. Also has a
13 tooth gear in place of 16 (on MKZ) to compenstate for higher
RPM. Glad to hear he put field in S/P (series-parallel) from all in
series. That cuts amp-turns in half and I squared R (field heat) by
factor of 4. He probably has no need to bring out 4 field
terminals. Just leave in S/P.
Easiest way to connect them was to use the old A1 and A2 terminals. But a
good datapoint, I'll make sure Don knows to parallel connect them, not to
chance series. It may have ended yo easier to reinstall the fields with
only two termnals to line up instead of 4, I'll have a look at the second
motor and see if I have materials to put longer tails and not make a mess
of joining to the existing terminals!
Also a thought on the brush cross connectors where you have clearance
issues. Why not bring out 4 "A" terminals? Two A1's and two A2's. Then
just use a insulated (welding cable or the like) jumper on the
outside. If he is willing to live with four "S" terminals, how about four A's?
That is what I moved straight on to once I found the clearance issue - If
the clearance hadn't been an issue, the cross connections seemed to have
been less work than the 4 terminals, but you do what you have to do!
To fit the 4 'A' terminals, I drilled out the rivets holding the brush
insulator ring in place, machined the CE plate so that it is flat from the
outer edge of the bearing housing to the inner edge of the body step,
taking off the 'lumps' cast in for mounting the brush ring to, and various
cast-in numbers. I've machined a piece of insulation material that is as
thick as the space is deep, to set the brush ring back where it goes. I've
already machined the outside of the housing of the first motor to clear the
terminals.
I need to hollow out sections where the brush holders are riveted on, then
drill the new armature bolt holes right through the three parts. The holes
are 13.5mm (I forget the imperial size equivalent) which gives reasonable
wall thickness for the insulator over the 3/8" terminals.
I'll glue the spacer ring to the brush ring with epoxy adhesive on assembly
for extra strength - there are small cracks alongside each brush holder, on
the side of the holders away from the rivets, i.e., right where the new
terminal holes are going!
The new terminals are an "L" of copper bar with a 3/8" brass threaded rod
section silver-soldered to them. The side of the bar lays alongside the
brush holder edge, stopping the terminal from trying to rotate. the long
part of the bars are the brush tail connections.
Will have the first motor finished tonight (hopefully, doing it out of
working hours). Second motor won't take so long as I don't need to figure
out what I'm doing and I'll have some parts already made.
Jim, you asked how much time. Not including the time lost making the cross
bars I'm up to about 8 hours so far, I guess the mods will be about 20
hours for the two motors. If I had top-hat insulators available I would
probably save 3 hours (by the time I've turned up 8 of them).
So the list of work looks like being:
# Strip the motors down
# clean the years' of accumulated 'yuck' off them,
# Pull the fields
# more cleaning
# modify the field tails
# drill and tap the temperature sensor holes
# paint the insides of the field windings (not enough Fusa-Fab to re-do the
taping)
# whilst the paint is still wet, reinstall the fields and temperature sensor
# make sure the field tails are where they need to be and heavily paint the
entire inside oth the body tube
# drill out the brush mounting rivets
# machine the CE plates inside and out
# machine new insulating spacer rings
# machine new top-hat insulators
# make new L-bars and silver-solder terminal rods
# assemble brush holder parts
# clean up commutators
# reassemble motors
All in all, nothing particularly difficult or requiring exotic skills or
materials, but experience would save a lot of trial fitting and would make
the job look much better. With Jims' advice and Fusa-Fab supply it has been
quite achievable - but I'm not sure I would have tackled it otherwise!
Time to get to work...
Regards
Mini Me (..[Technik] James)
--- End Message ---
--- Begin Message ---
Hello Bill
A couple of factors your over looking.
AGM and NiMH batteries do get out of balance. Most BMS systems address this
by applying a slight over charge to all the batteries. Batteries are not all
perfect some fail very soon others a little later then the rest.
You are not giving any value to the effect of not taking all the good
batteries and exposing them to the highest level of charge they can possibly
take.
So not are you only bringing up the lowest batteries your also keeping your
best batteries good longer. One might be able to replace a few failed modules
and retain the others because of less over charging. It is a better charging
algorithm not to kill your best modules in order to just bring up a few low
ones. The ones that are going to fail before the others do no matter how they
are charged.
The greatest cost of running an EV is the batteries. A thousand dollars up
front is going to save for years. A great value of the balancer is the damage
you do not have from years of over charging them.
Don
In a message dated 3/5/2007 11:22:11 AM Pacific Standard Time,
[EMAIL PROTECTED] writes:
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
<BR><BR><BR>**************************************<BR> AOL now offers free
email to everyone. Find out more about what's free from AOL at
http://www.aol.com.
--- End Message ---
--- Begin Message ---
Just curious, did you calculate the distance the tire travels based on
measured circumference, or radius?
Radius would seem to me to be a more accurate measurement, and would
change based on tire pressure.
>
> 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
>
>
>
>
>
>
>
--
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.
--- End Message ---
--- Begin Message ---
Another 'option' - not a cheap one, but it is what OEM ICE developers seem
to use now, is Matlab + Simulink + real-time workshop / autocoder. This
allows similar control development as Labview, except then you can generate
embedded code for use on other target systems - the Power PC MPC56x family
appears to be the most common. Some people are even doing less demanding
stuff on the Freescale MC9S12 family using this method.
If you were into 'rolling your own' hardware, you could fairly easily use
one of the Microchip PIC devices and one of those little flash cards - MMC
cards are quite easy to use.
I just built up a datalogger for work - specifically, it logs ICE engine
data from an ISO14230 interface - to one of these cards. It took about two
months of hardware and software work - mostly to support USB - and used the
Atmel AT91SAM family of parts. The GCC under Win32 development environment
worked well.
-Dale
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--- Begin Message ---
thanks Mark. I wonder if there is educational pricing... I'll google around a bit. The same issue came up on another,
gas-powered, forum.
Mark Brueggemann wrote:
--...
but its pricey.
Yes it is, but given it's breadth of application in an EV
environment it could be easily rationalized ...
have you run across an Open Source version of LabView?
None that I'm aware of.
...
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 ---
ok, I'm still a novice, I looked at the data
sheet...looks like its bit 7 and 0=general purpose
I/O..this may seem like a dumb question but how do I
clear that bit? I'm using picbasic pro for the
compile.
there is a LVP and an ICSP check boxes on my
programming software (picall), these boxes are NOT
checked. suggestions?
Thanks again!!
Brian B.
--- Kaido Kert <[EMAIL PROTECTED]> wrote:
> See chapter 11.18 of the datasheet. pin 3 of the
> chip is the flash
> programming pin used for in-circuit programming. It
> defaults to being
> set to this mode from factory defaults.
> If you dont do incircuit updates, clear the LVP bit
> in the
> configuration word and if works as a GPIO pin again.
> For details, Read The Fine Manual, especially that
> chapter 11.18 :)
>
> -kert
>
>
> On 3/5/07, brian baumel <[EMAIL PROTECTED]>
> wrote:
> > greetings everyone,
> > I am almost done with building a custom
> speedometer
> > for my EV. I am have a small problem with it
> thought,
> > one pin to be exact. I am using a PIC16F872 portA
> is
> > all inputs, port B and C are directly coupled to
> some
> > 7447 display drivers(3 digits, 3 display drivers).
> my
> > problem is in portB.3 this pin will just not
> toggle!!!
> > I have tried 2 different PIC16F872 and a
> PIC16F876A
> > none will toggle PORTB.3.
> > I have programmed it so that ports B and C blink,
> but
> > that one pin just will not toggle on any
> occassion. am
> > I forgetting to disable/enable something, like
> what is
> > done to turn off the ADC on portA (ADCON1=7)??
> > the data sheet says something about PORTB.3 is a
> I/O
> > or a PGM...some type of medium voltage programming
> > mode.
> > some one please help. right now I'm using a bike
> > speedometer and it sucks.
> >
> > thank you,
> >
> > Brian B.
> > 81' Bradley GTII
> >
> >
> >
> >
> >
>
____________________________________________________________________________________
> > Food fight? Enjoy some healthy debate
> > in the Yahoo! Answers Food & Drink Q&A.
> >
>
http://answers.yahoo.com/dir/?link=list&sid=396545367
> >
> >
>
>
____________________________________________________________________________________
Expecting? Get great news right away with email Auto-Check.
Try the Yahoo! Mail Beta.
http://advision.webevents.yahoo.com/mailbeta/newmail_tools.html
--- End Message ---
--- Begin Message ---
indeed. thanks.
meantime I also found this on an RC site
http://slkelectronics.com/DeWalt/index.htm
Dmitri wrote:
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:
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following up:
I found one defunct and one brand new XP-only project on SourceForge, so no help there. There are over 30 LabView
extensions or apps there as well.
LabView does have a free student edition:
http://www.ni.com/academic/edu_lic.htm
John
john fisher wrote:
thanks Mark. I wonder if there is educational pricing... I'll google
around a bit. The same issue came up on another, gas-powered, forum.
--- End Message ---
--- Begin Message ---
Lee Hart wrote:
Don't use aluminum for a connector. It forms an insulating oxide
coating almost immediately on contact with air, so you are sure to get
bad connections.
Copper isn't much better; it also soon forms an oxide coating (it
doesn't take long for shiny new copper to turn brown or green).
Aren't the + and - terminals of ThunderSky cells aluminum and copper?
Do they need to be "de-oxided" somehow before having connectors attached
to them? Is there a conductive paste that needs to be applied to them?
Thanks.
Bill Dennis
--- End Message ---
--- Begin Message ---
>> Don't use aluminum for a connector... Copper isn't much better...
From: Bill Dennis
> Aren't the + and - terminals of ThunderSky cells aluminum and copper?
I have some Thunderski LP90 cells, and they have nickel plated hardware. I
would strongly doubt they would use aluminum or copper on other models.
--
Lee Hart
--- End Message ---
--- Begin Message ---
Hmm, ok. I'll try to keep this simple.
Let's start with a little physics lesson/refresher.
If you pass a wire through a magnetic field in such a way that it cuts
across the lines of force, you will induce a current in the wire.
Likewise if you have the same setup, but don't move the wire, and you pass
a current through the wire, it will generate a magnetic field which will
push against the existing field and try to move the wire.
The first principle is what generators are based on, the second is what
motors are based on.
The important thing to keep in mind is that basically all motors are
generators, and vice versa.
The REALLY important thing to keep in mind is that basically every
motor/generator performs BOTH fuctions AT THE SAME TIME.
So while your motor is motoring, it is also generating electricity
internally. This generated voltage apposses the applied voltage and is
what stops the motor from continuously accelerating. This is normally
called a "Back ElectroMotive Force" or BEMF.
The BEMF appears from the outside to be a variable resistance that
increases as the RPMs go up, and it limits how much current the motor will
draw.
Basically the applied voltage minus the BEMF equals the voltage the motor
"sees" internally. Divide this voltage by the internal resistance of the
motor and you can determine how much current the motor will draw.
The amount of BEMF produced depends on the RPM of the motor and the
strength of the magnetic field surrounding the spinning armature.
Anyway, the important thing to remember is that the BEMF determines the
speed to motor spins at. Reduce the BEMF and the motor draws more current
(larger difference between applied Voltage and BEMF), and because of the
extra current the motor has more torque and it speeds up. Which increases
BEMF and at some point (normally) ballances out and the motor stops
accelerating.
Oh well, so much for keeping it simple.
Ok now let's talk about shunt motors. These work kind of backwards to
what most people would expect, but if you understand the above, you'll
understand why they work like they do.
Since your motor has separate shunt field terminals, I'm going to assume
it has separate terminals for both the series field and the armature
(connected to the brushes).
Power up the shunt field FIRST with 24V (I'm guessing that's the right
voltage for the shunt). Then apply voltage to the armature (brushes).
Now here's the cool thing, if you apply a load to the motor it will try to
spin at just about the same RPM as it does without a load. This is
because with a shunt motor the BEMF is independent of the load and/or
applied current. It depends solely on the RPM. It will slow down
slightly under load, enough to draw more current and ballance the input
power to the output power.
Now to adjust the speed of the motor you reduce the voltage across the
field, this will cause the motor to speed UP. Yup, that's right, reduce
the voltage on the field and the motor goes FASTER. That's because
reducing the field voltage reduces the magnetic field which reduces the
BEMF so the motor draws more current and spins faster to build the BEMF
back up and ballance the equation.
So basically, as long as the speed the motor turns at, with full field
voltage, is slow enough for you, then you don't need to adjust the
armature voltage (it can be full pack voltage). This means you only have
to control the armature voltage/current and this is MUCH lower current
than the armature draws. You can probably even control it using a high
power rheostat (like a big wire wound variable resistor).
However, electric bike controllers are dirt cheap these days and one of
those would probably work to control the field. Just make sure you turn
it on and then go to FULL voltage (what would normally be MAX speed on a
bicycle) before you turn on the armature, in order to keep the motor at
minimum RPM.
So all you'd need is the low power controller for the field and a
contactor for the armature.
Using it as a shunt motor is probably your best option since you won't
over spin the motor if it starts to cavitate. This is because it will
want to spin at about the same RPM without a load as it was under load.
It will spin a bit faster without a load, but it WON'T try for infinity
like a series wound motor.
Oh yeah, you can also reverse it easier as a shunt motor because you can
simply reverse the armture current or the field current. Even though it's
easier to reverse the field, I'd probably do the armature to make sure you
don't have the armature powered up with no field current. If you do this
(no field current) it will try to operate similar to a series wound motor
and will shoot for infinity and beyond. At the very least it will draw
HUGE ammounts of current through the armature. With little to no BEMF the
current is only limited by the internal resistance of the motor (way less
than 1 ohm)
So don't EVER have power on the armature without current running through
the field. You will probably need to add some safeguards on the
controller to make sure that it always goes to FULL voltage BEFORE you
turn on the armature.
That's not the clearest explanation I've seen, but hopefully you
understood it.
Cheers, Pete.
> 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
>>
>>
>
>
--
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.
--- End Message ---
--- Begin Message ---
> I have have done the math and I know the air car idea is not very
> efficient but what if the compressed air half was cheap
But it's NOT cheap.
-snip-
> So we buy essitially rent/exchange buy a scuba tank of air when we need
> range extension. (Last I heard it was $35-$50) to refill at the local
> dive shop, we used it to refill our 3000psi paintball tanks.
Let's see. IIRC someone said that a SCUBA tank stores about 350 wh of
power. So, $100 to $150 dollars for 1 kwh. It only costs $0.10 at the
wall outlet.
Yup, DEFINITELY not cheap.
--
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.
--- End Message ---
--- Begin Message ---
brain what are you doing for a speedometer ? are you mounting a display of
some sort ? I wanted to use a touch screen for my gt2 e but have not found
anything that will work and be powered by dc voltage . I wanted to display
speed / motor volts / motor amps and maybe rpm or pack voltage . are you using
a pc ?
----- Original Message -----
From: brian baumel<mailto:[EMAIL PROTECTED]>
To: [email protected]<mailto:[email protected]>
Sent: Monday, March 05, 2007 10:09 AM
Subject: PIC help
greetings everyone,
I am almost done with building a custom speedometer
for my EV. I am have a small problem with it thought,
one pin to be exact. I am using a PIC16F872 portA is
all inputs, port B and C are directly coupled to some
7447 display drivers(3 digits, 3 display drivers). my
problem is in portB.3 this pin will just not toggle!!!
I have tried 2 different PIC16F872 and a PIC16F876A
none will toggle PORTB.3.
I have programmed it so that ports B and C blink, but
that one pin just will not toggle on any occassion. am
I forgetting to disable/enable something, like what is
done to turn off the ADC on portA (ADCON1=7)??
the data sheet says something about PORTB.3 is a I/O
or a PGM...some type of medium voltage programming
mode.
some one please help. right now I'm using a bike
speedometer and it sucks.
thank you,
Brian B.
81' Bradley GTII
____________________________________________________________________________________
Food fight? Enjoy some healthy debate
in the Yahoo! Answers Food & Drink Q&A.
http://answers.yahoo.com/dir/?link=list&sid=396545367<http://answers.yahoo.com/dir/?link=list&sid=396545367>
--- End Message ---
--- Begin Message ---
Hello my name is Karsten and I am researching building my first
electric vehicle. I am interested in using an electric in wheel motor.
I wanted to build an offroad (but street legal) vehicle to start with,
because I know my range and speed will be limited by my budget. I was
thinking of taking an old ford bronco rolling chassis and converting it
to electric. The ford Bronco with a fiberglass body is a pretty light
vehicle if I could take out the transfer case, transmission, etc...
Having 4 independent electric motors as wheels would be incredible for
4wdriving. Are there any other manufacturers for in wheel electric
motors? Are there any other options that I can convert to make an
electric wheel? Any info regarding electric motors in wheels would be
greatly appreciated. Thank You.
--- End Message ---
--- Begin Message ---
go to the cable mfg and ask for specs or use the general guidelines in the
n.e.c.
----- Original Message -----
From: Bruce<mailto:[EMAIL PROTECTED]>
To: [email protected]<mailto:[email protected]>
Sent: Sunday, March 04, 2007 11:44 PM
Subject: Measuring Cable Resistance
How exactly does one measure the resistance of battery cables? It is too
small of an amount to measure with my common multimeter.
Bruce
Cor van de Water wrote:
> you need to add the resistance of your cabling.
--- End Message ---
--- Begin Message ---
I'll check tonight, but it must be my mistake. I thought I remembered
the terminals being brown and silver.
Bill Dennis
Lee Hart wrote:
Don't use aluminum for a connector... Copper isn't much better...
From: Bill Dennis
Aren't the + and - terminals of ThunderSky cells aluminum and copper?
I have some Thunderski LP90 cells, and they have nickel plated hardware. I
would strongly doubt they would use aluminum or copper on other models.
--
Lee Hart
--- End Message ---
--- Begin Message ---
Just to give a closing update about the SCR's I mentioned a short while ago
which were going cheap.
I have finally heard back from the seller, who says he can let me have any
number for £4 each, he has over 100.
The specs are in the last of my blog messages, here
_http://journals.aol.co.uk/fixitsan/electric-car-building/_
(http://journals.aol.co.uk/fixitsan/electric-car-building/)
I appreciate I didn't contact anyone who wrote back to me about this, but I
needed to wait to be told the final unit cost.
I may be buying a few more myself, but should anyone want any for themselves
the seller has allowed me to disclose his details which are as follows
His name is Dave, and his email address is [EMAIL PROTECTED]
(mailto:[EMAIL PROTECTED])
(reimann<space>AThotmailDOTcom)
He will sell them for £4 plus the actual postage cost, bear in mind the
weight of the bases/mounts, I haven't asked him but he may be willing to take
the SCR capsules out of the mounts and ship them on their own to save shipping
costs.
Chris
--- End Message ---
--- Begin Message ---
I agree AC systems on EVs are undesireable, but when you live in a place that
routinely hits 115-125F in summer its not really an optional feature.
Here's one example I found. Its pretty boxy, but there is something to be said
for a self contained unit. The Kar Kool 212 from Southwest Solar uses 20W at
12.5V plus 0.5gph of water to produce ~30 degrees cooling at 200cfm. Sounds
like a reasonable amount of cooling for most EVs, and I'm assuming this power
is much much less than any AC system. This box is actually meant to sit in the
passenger compartment, which may not be a bad place for it. I'd prefer an
under hood mount, but as mentioned I'm not sure the dash ducting in most cars
can move this much air. I'm also not thrilled at the prospect of suspending a
gallon of water on the firewall above my high voltage components :-)
http://www.nvo.com/southwestsolar/
Here's another company that makes true evaporative and ice based portable units:
http://www.swampy.net/ac12.html
And a company that makes the classic window mount type:
http://www.classicaire.com/
I like the window mount, but wonder how much of a drag hit you would take?
Rob
--- End Message ---
--- Begin Message ---
Of course gas wouldn't be cheap either if gotten from scuba shops. :-)
Remember air is as cheap or cheaper than gas because it can be 100%
efficiently compressed IF the waste heat arises from compressing it is
recovered and offsets some other heat used such as building heat or
water heating. It is only inefficiently compressed if the waste heat is
dumped.
PLUS since the air is deleivered via the atmosphere for free to all the
surface of the earth there is no distribution cost to the plant unlike
natural gas or gasoline or even electricity.
If your house had its own air compressor and you recovered all the waste
heat and offset your other electric heating needs like house heat and
water heat with it then your cost of compressed air would be minimal.
One other nice thing about compressed air is its power expansion phase
creates a cooling effect so it can be used an an alternative to
otherwise power hungry air conditioning in a car.
So that raises its over all efficiency as part of a total car system of
air and electric mix..
On Mon, 5 Mar 2007 3:08 pm, Peter VanDerWal wrote:
I have have done the math and I know the air car idea is not very
efficient but what if the compressed air half was cheap
But it's NOT cheap.
-snip-
So we buy essitially rent/exchange buy a scuba tank of air when we
need
range extension. (Last I heard it was $35-$50) to refill at the local
dive shop, we used it to refill our 3000psi paintball tanks.
Let's see. IIRC someone said that a SCUBA tank stores about 350 wh of
power. So, $100 to $150 dollars for 1 kwh. It only costs $0.10 at the
wall outlet.
Yup, DEFINITELY not cheap.
--
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.
www.GlobalBoiling.com for daily images about hurricanes, globalwarming
and the melting poles.
www.ElectricQuakes.com daily solar and earthquake images.
--- End Message ---
