Monday, May 21, 2012

Escaladus Interruptus and the Catellier Effect

This week, we were hard at work in the 2008 Electric Cadillac Escalade EXT conversion and we are at a very rewarding phase of the build where things move along quite quickly.

Tim Catellier of Chandler Arizona slipped in and mounted a small explosive device under the hood and this kind of wrecked our week.

Tim, an EVCCON 2011 attendee, and so of course a rank up in standing over "ordinary" viewers, inquired about a pleasant little puzzle he was having with his BMW Z3 conversion. He had been at EVCCON 2011 with his erstwhile assistant, his FATHER, and we were privileged to examine first hand and up close the particulars of this Zilla/Netgain build using CALB cells - excellent in all respects. He in turn claims the drag racing and autocross was the most fun he'd had in a car EVER with his pants on and no music.

It seems he had developed a "frame leak." I'm actually extraordinarily pleased with this. We had done a show that prominently featured our efforts to chase down a frame leak on the 2009 Mini Cooper Clubman. We described what they were, how you could detect them, why it was important for your personal safety NOT to have one, and how to chase them down. We have since had a regular flow of viewers who HAVE found frame leaks subsequently.
While most were minor leaks in the 30 ma range, some have been serious. So I'm kind of pleased this particular episode caused a lot of people to check their systems for leaks, and more pleased that they have largely been successful in addressing them. I'm not precisely a safety Nazi. Life's a bitch, and then you die, and ho hum. But this one has caused us some nasty shocks in the past and so it deserved some attention. Apparently the problem was not as rare as I thought. It wasn't just us. And so, as Marthaa Stewart says, "That's a good thing."

The check is simple. Connect a multimeter between any battery terminal and frame ground. You should see a varying voltage of 4 to 6 volts. It will probably jump around. This is because the pack "floats" separately from frame ground. If you read ANY steady voltage above a volt or so, you have a frame leak. If you read DIFFERENT steady voltages based on which battery terminal you measure to ground, you certainly have a frame leak.

If you connect a 12v light bulb between the terminal and the frame and it fails to light, it is probably a very minor leak of 30 or 40 ma usually through some of your instrumentation. If you get any light, you have a serious situation that can be life threatening in the right environmental conditions - like sweaty skin.

In any event, Mr. Catellier had one. ANd after carefully and logically troubleshooting the problem, isolated it to the MOTOR. DC series motors of course have brushes and a commutator. Carbon conducts. And a buildup of carbon dust within the motor is not unusual. Sufficient carbon dust can short the field windings to the case. Actually this is so common that a leak of less than 30 ma is not even considered a problem by the motor manufacturers. Tim's was more in the 800 ohm range which into a pack his size, is pretty stout.

He tried blowing the motor out with compressed air and failed to eliminate the problem.




George Hamstra, of Netgain Motors had previously rebuilt this same motor and wanted a clean slate on this problem. After examining photos of the brushes, he asked Tim to send in the motor and he shipped him a brand new motor from Warfield, complete with the latest Helwig H60 RedTop brushes.

It was a non-trivial amount of work to swap out the motor. But Tim again enlisted the aid of his erstwhile assistant, DAD, and they were able to do it in some four and a half hours. The frame leak was gone. And they reassembled the car.

He was back on the road and drove it to work and back the next day. But there was an interesting difference. Tim had kept careful records over the past 26 months and tracked energy usage, electricity costs, gasoline prices, and right down to the dollars dimes and ducats saved in not purchasing gasoline, all in a handy spreadsheet, just as a proper Computer Systems Administrator is wont to do.

The car averaged 380 Wh per mile for over two years. In fact, Tim and I had actually had a conversation earlier about this as we have a pretty strong rule of thumb that a car will use about 1 Wh of energy to move 1 Mile over time and average, for each 10 lbs of car. Tim's car weighed in at EVCCON 2011 at 3285 lbs. And 380 Wh/mile somewhat exceeds our rule of thumb. I was unable to account for this or provide a persuasive theory. Maybe my rule of thumb not so good medicine in all cases.

On his drive to work and back, Tim noted an energy usage of 280 Wh/mile. This is kind of dramatically better.

He describes this somewhat better than I do on his blog at http://evz3.blogspot.com/

I received an e-mail message regarding this. In discussing the issue, he refined his results with total driving over the past 680 miles - 332 Wh/mile average. At 3285 lbs, I like this number for by now obvious reasons.

I initially suggested that the only thing I could imagine would cause such a DRAMATIC disparity in two otherwise identical 11 inch motors was the advance timing. The Netgain motors come marked with alignment marks for CCW, N, and CW timing. This corresponds to counter clockwise as viewed from the drive end of the motor, neutral, and clockwise respectively.

Most explanations of electric motor theory are technically correct as far as they go, but of necessity incomplete. First, some of the factors are difficult to explain. And second, after 150 years some of them we really don't know exactly. For some reason, "square" motors - that is motors with a certain ratio between diameter and length, run better than others. A certain amount of mass of iron in the case is simply required for efficient operation. We CAN make motors lighter. That's not necessarily a good thing. We know that the field windings set up a magnetic field that causes armature rotation. But were you aware that there is an interaction where the armature rotation then affects the magnetic field - in fact rotating it in the direction of the armature?

This is termed the armature effect and actually we DO know quite a bit about this. In the Netgain Warp 11HV, they employ inter poles to counteract the effect of this, and this is how this particular motor can handle higher voltages without arcing.

In the ordinary Netgain Warp 11, the CCW position literally rotates the brush ring a few degrees in the direction of armature rotation. This moves what is termed "the neutral plane" that same number of degrees. And so the brushes are only truly at neutral when the motor reaches a couple thousand rpm and the armature effect comes into play. Since it is OUT of neutral at low rpms, you would think this would cause arcing on startup. But in fact, the actually applied voltage to the motor is very low at that point and so arcing isn't as much of a problem. Under power AND RPM, the voltage is higher, and so that is where we want the brushes to truly be in the neutral plane.

And so we refer to this as ADVANCE TIMING. My theory was that if Mr. Catellier had his first motor accidentally at N or worse CW timing position, this would cause severe arcing during acceleration - and probably a LOT of carbon dust. That could seriously undermine his Wh/mile and explain his frame leak.

Unfortunately, brilliant though it sounded, it was another case of my trying to type myself smart in a fashion that would make the DIYElectric crowd cheer with pride.

Tim had of course noted and recorded the position on both motors. CCW. Theory busted.

Leaving what? The brushes. I'm accustomed thinking of brushes as just brushes and that their main characteristic is their life span, based on the hardness of the material. This also becomes a factor in seating the brushes, as they can take longer or shorter amounts of wear to properly seat in. But once they are in operation, there is little to choose between them other than how many miles you get before you get to change them. The technology is 180 years old. What's to know?

But in the spirit of rational inquiry, what else is there? That was the notable change between the two motors.

I happened to have a Netgain Warp 9, and an ADC 8 motor on a bench I had cleared off. We reassembled the Warp 9 using the new Helwig H60 Redtop brushes and painted the motor. The ADC took a little more work, we bead blasted the end bells, (and the armature unfortunately), revarnished the armature, and replaced the brushes and the entire brush mounting ring. I intend to use it on a lawn mower.

But we looked around and found the old brushes from the Netgain Warp 9. I wired up a JLD404 meter and a digital voltmeter with a contactor, one of our A123 13.5volt modules, and a switch. And we ran the motor with the new brushes, that had about 10 hours of seating on them. Then we changed the brushes to the old brushes. As it turns out, these aren't Helwig brushes at all. They are marked ML1683 and ML1684 H8 with a stylized chevron with a capital N in it. I have not determined who the manufacturer is, but Tom Brunka advises that it is a low voltage brush used on fork lift motors typically at 72v and below.

So we ran the motor again with the old brushes. The difference was astounding. For the same 129Ah of energy, the new brushes ran for 3 hours 38 minutes and 54 seconds. The old brushes ran for three hours, one minute, and 25 seconds.

So we reran the new brushes again. Along the way, we began recording RPM and commutator temperature along with current and voltage. The results are shown below.




If you clear out all the chaff, the new brushes use 485 Wh per hour to turn the motor at 2652 rpm while the old brushes require 535 Wh per hour to turn the shaft 2053 rpm. This is such an astounding difference that there must be something HUGE wrong with our methodology.

Except it rather persuasively reflects, in both direction and amplitude, what Tim Catellier reports.

I really have no further explanation for this. Here is the data and we would be very interested in direct attempts to reproduce either refuting or supporting. In the meanwhile, if you are driving a Netgain Motor a year old or more, you might invest in a set of Helwig H60 RedTops. Baseline your Wh/mile, change the brushes, and measure again. We would be very interested in what you find.

The current Helwig part numbers are:

For the Warp 9 = 10-621117-674-3-01
For the Warp 11 = 10-621117-674-3-02

I think Netgain is offering these brushes now at $150 per set of eight brushes. We will try to do the same on the EVTV online store as soon as possible.

We have also chased down the XSTURBOS guy and ordered 10 of his Garret blowers. We'll put together a little kit with the blower, the shroud for the motor to mount it on, and a relay at $495. George Hamstra of Netgain has already spoken for one for his Bricklin build that we are hoping to see at the EVCCON 2012. But hopefully we'll have these up on the web site this week or next as well.

Why? The main defense you have to carbon dust buildup in the motor is the motor fan. The newer motors actually have an improved fan on the drive end and these fans do a pretty good job at moving air through the motor, both to cool it and to clear the inevitable carbon dust. The problem is, that works real well at 3000 rpm. It works not so well at 300 rpm. And at 20 rpm it doesn't do squat. We have routinely begun using these 434 cfm blowers on all our Netgain motors. Any more heat you can remove is a good thing. And at low rpms, you still have fairly impressive air flow to remove carbon dust as well as heat.

Many people have run Netgain motors for years quite handily without an external blower. So this is overkill EVTV style. Still we recommend it.

Additionally, there are many less expensive blowers that are out there that will do just fine as auxiliary blowers for the motor. These look cool. For what i'm spending on the Escalade build, looking cool is kind of required.

Your mileage may of course vary....

Jack Rickard

82 comments:

  1. This comment has been removed by the author.

    ReplyDelete
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    1. Jack, again you produced a new video just in time to answer my latest burning question -- how much power does it take to turn a Warp-9. Last week I connected my new, fresh from the factory Warp-9 to a new, fresh from China 50 amp variable power supply.

      After running for a couple of hours, my motor (Serial #NM0000015), draws 30.2 amps at 12 volts. This was just the motor sitting on blocks on the bench. I currently do not have an accurate way to measure RPM nor a non-contact temperature readout. I would guess the speed to be 1500 to 2500 RPM and the temperature at the shaft is around 100F.

      I did note two additional things. First of course is that my motor draws less than yours even when you ran with the Helwigg brushes. I have not yet opened up my motor to see which brushes were shipped. As I plan to order a spare set from you, I will be checking my brushes this week.

      Second (and this is only subjective), my motor seems considerably quieter than yours. This could be caused by a large number of uncontrolled factors, including the fact your microphone was very close to the motor during the taping. But if your motor is noisier, it most likely is an indication of why there is a 120 W difference in power consumed between these tests.

      Like you, I am also surprised that such a low tech device as a brush can impact the performance of the motor so much.

      Keep up the good fight,

      Roger...

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    2. The purpose of the test was not to establish the ideal, but compare two sets of brush's. And it may not be an entirely fair test, though it does kind of put a point on Mr. Catellier's observations.

      Ideally, you would thoroughly clean a commutator and perhaps even turn it. A new set of brushes would be fitted. The motor would be turned with no load after teh fashion of our test. This would allow the brushes to wear a bit and transfer carbon to the commutator, building up a patina of carbon. After some hours of this process, the brushes would be seated.

      We had old brush's that didn't look well seated to me. We put in new Helwigs and ran it about 10 -12 hours. Some seating. Then we put the OLD brushes on with the carbon on the commutator that is a mix of old and new. THEN we put the NEW brushes back on, and as you can see in teh video we were up around 41 amps initially. As they seated, that came down to 33.

      Finally, as you know, we were at 13.4 volts, not 12. So its apples and onions all around.

      But yes, broadly 30-40 amps and 2000-2500 rpm. After an hour, you'll see somewhere between 140 and 210F at the commutator.

      Jack Rickard

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  2. Very interesting discovery thanks for you hard work on this topic.

    Looking forward to results on a loaded motor, that would resolve any doubt on the scale of efficiency gained.

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    1. We have no intention of a loaded motor test. You're doing exactly as I feared. We have a question. Now we have an answer. And then immediately everyone will start applying the answer to a different question.

      We haven't done anything on motor efficiency.
      Oh, some rough dynocalculations about a year ago.

      This is NOT a test of motor efficiency at all. And there was no such gain in motor efficiency.

      I'm told that these brushes MIGHT provide a 1.5% gain in motor efficiency.

      So there is a very real danger of mixing apples, oranges, and sunshine here.

      Motor efficiency looks something like this. I put in 149,200 watts of electric power and get 200 hp to show up on the shaft. That would be 100% efficiency. In reality, I put 149200 in and get 88% through MUCH of the rpm range - 176 HP.

      But if I can get 176 horsepower for 149,200 - 1.5% or 1500 watts to 147,700. COOL.

      Now what are we doing. If we do 1500 watts of savings for an hour, we have 1500 Watt-hours (Wh). Tim gets 332 Wh per mile. That's between four and five miles of range.

      The difference is we have made two huge leaps here. Watts per hour, and Watt-hours per mile. And so we can improve those rather vastly, with very small changes in "motor efficiency".

      We have already seen the test "loaded." We STARTED loaded with Tim driving normally for 680 miles at an improved "efficiency" in Wh of energy burned PER MILE. So you've got PER HOUR bolluxed up with PER MILE.

      What this test did was confirm that it was the BRUSHES that caused the improvement. We can see the same percentages just running the motor on a test bench. But again, we are doing it by the length of TIME the motor runs on a given amount of energy - unloaded.

      So it is a cumulative gain we are looking at. This is stored energy expressed as energy over time, then applied to miles. If you try to back that up to similar levels of MOTOR EFFICIENCY, you're off by an order of magnitude.

      I don't know that I did, but it would be a perfect Alzheimer's moment if I DID say something about "motor efficiency" in the video. If I did, I mispoke.

      But the range gain stands. The time the motor runs comparatively stands. And if YOU want to do a loaded motor test to somehow compare that, we're of course very interested in your findings.

      Jack Rickard

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  3. I hope you share you lawnmower build on EVTV. It seems patently obvious brushes could affect motor efficiency. I think what you shared about the esoteric design constraints of "square" motors only underscores this. It seems unimaginable brushes would be brushed off for 100 years. So why were what appear to be specific use/purpose built motors equipped with what are apparently inappropriate brushes? Did the weak brushes shave off seventeen cents of manufacturing cost, or has some sort of unspoken industry governor been discovered? At least it makes more sense why no one would touch my dual stator question with a ten foot pole. I am still wondering why DC motors sans brushes are not an option for larger electric vehicles.

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    1. Perin,
      Brush technology has been half forgotten with time? Maybe with some.

      I do recall reading a little about them as a young lad.
      They are sacrificial, self lubricating and a means to an end in an imperfect world.

      Some have silver loaded brushes in their Agni motors yet normal brushes used gently are good for 50,000 miles or half a seasons racing. How much would you like to pay?

      There's plenty of alternative motors but once again, how much do you want to pay?

      Delete
    2. Andyj, Does a brush-less DC motor exist which would be suitable for large EV conversions? There are brush-less DC motors for bicycles and motor-bikes and -scooters. In last weeks blog comment area I shared a link to a dual stator motor. The "square" motor business makes me believe there might be more than meets the eye regarding all sorts of stuff, including the Motionless Electromagnetic Generator. I can't overlook the fact that planned obsolescence is ingrained in the societies and manufacturing chains of the developed world.

      Delete
    3. You can check out say the Emrax
      http://www.enstroj.si/Electric-products/emrax-motors.html

      Or rip the bits out of say a Prius?
      http://www.electrifyingtimes.com/p1-9b.gif

      Both are 30KW @ 100% duty.

      One of these could easily give my trike 1g acceleration. 0-100kph(60) in 3 seconds!

      The "Motionless Electromagnetic Generator" is a fraud.

      Delete
    4. The MEG reminds me of the square motor business. Heavier than air flight was once unimaginable, too.

      The website you shared indicates the prototype motors are priced similar to the same powered brush motors, and that this motor has the highest power to rate ratio of any motor in the world. Sounds like something Jack might like to employ. I have no need for extreme speed or acceleration, so 0-60 times are not of much interest to me.

      http://web.mit.edu/scolton/www/SCThG.pdf
      (excerpt) "Brushless permanent magnet synchronous motors (PMSM) are increasingly replacing brushed
      DC motors in low- to medium-power servo applications. In these motors, electronic
      commutation is used in lieu of mechanical brushes. This reduces friction, increases reliability,
      and decreases the cost to produce the motor itself. The tradeoff is more complex and expensive
      controllers. However, the economies of scale of electrical components are very different than those of the motors themselves, and a system-wide cost/performance evaluation favors brushless motors in many applications."

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    5. Yup.
      Brushless needs mass production for controllers to match the motor, the use and make the savings.

      Dan done well pointing out the likes of the Prius. Two stripped units would make a killer 2 or 4 wheel drive EV on the cheap.

      Delete
    6. I just now went to your .gif. Not enough information for me to understand the usage context. I was also worrying you were using some slang with the "bits". Have you [or Dan] contacted a parts yard to see if there is a secondary market for the motors? I also mistyped. The correction is "...power to weight ratio..." I haven't read the .pdf I shared, so I'm unsure just what the threshold for mass production would be. Brushed motors seem like steam locomotives.

      Delete
    7. Hi Perin,
      Sorry not noticed the reply earlier.
      Details, details. ;)

      http://www.electrifyingtimes.com/priustechspecs.html

      A second hand crashed/failed Prius is down to your local area costs.

      They have made these things do 70mph in EV mode but the battery S.O.C. meter was ticking down like a clock!

      Dan's not making anything but to me, I like! I've issues with garage space to strip an extra vehicle and need to know what's what and need to modify.

      My present motor/controller order is constantly being put back and patience is wearing thin. Might end up destroying this company and seller if they keep this up.

      *Most* electric motor types are something like steam piston engines: Max torque from 0 rpm. As you saw on the .gif file.

      One-off electronics are unobtainable and stupid expensive. DC series is more simple.

      Delete
    8. you can get a scrap forklift DC motor and build a cougar controller kit

      Delete
  4. Good show Jack. I think you are on the right track about why the harder brushes are more efficient. I think it does have to do with heat.

    I suspect that the harder Carbon produces a smoother surface than the softer carbon. Softer Carbon tends to break off in larger particles as it wears. I'll bet that this causes more pitting and slightly more arcing on the commutator surfaces which causes more energy to be lost as heat.

    The harder carbon probably breaks off in finer particles and causes less arcing...

    It is just a guess, but it sounded good in my head...

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  5. Jack: you observed greater power consumption and higher armature temperatures with the old brushes and surmised that the difference was friction.

    Might it perhaps have been a difference in electrical resistance across the brush/commutator interface? This seems more likely to me as I would have expected that enough friction to make a measurable difference to a Watt hour per mile number would tear up the brush, the commutator or both.

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    1. Damn you Mr. John Hardy!
      You beat me to the base on MY theory.

      Delete
  6. I wonder if anyone has done a brush swap with both sets of brushes that have been run in then measured the static resistances of both types from brush to brush through the motor while assembled? The harder brush ought to have a higher metal content or a more dense carbon medium.

    A lower resistance should allow more power at/or a lower voltage so more rpm and less losses.

    My presumption is the static friction *stiction* is similar for either brush type and a ridiculously small absorption compared to the power output.... But whats in the harder brushes?

    I love a good mystery.

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    1. It could not only be what's in the brushes but what is the size of what's in the brushes. In EDM mold work the size or granularity of the graphite particles that make up the electrode has a profound effect on the surface finish of the part and effects the electrode wear tremendously. EDM is really a just an arc or spark that is submerged in dielectric fluid.

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  7. Jack how many people have signed up for EVCCON? Would it be possible to slip in cheaper for just the drag race part or pay for just 1 day or does one have to pay full fee no matter how little time is spent at the conference? Thanks for your show and it looks like it would be great to go to EVCCON even if for just one day.

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    1. No one has signed up as yet. We're hoping for a guy in July.

      Yes, it is possible to slip in at the event on a one day pass at $595.

      Don't worry about it until you get here....

      Jack

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    2. Got it, no discount. I thought it was worth asking to see if it was like other conferences I have attended.

      I imagine you'll get a big rush of sign-ups at the end. It would be interesting to see how effective the early bird sign up discount will be in getting people to sign up early.

      Delete
    3. IT's been pretty effective. I think about 75 have signed up and they are piling in this week for obvious reasons. We are running a bit ahead of last year which makes sense and is a relief as I've taken a much larger facility for this year with the ShowMe Center arena.

      Hopefully it will remain small enough to do the parts I want to at the shop, at my house, and of course the airport has tons of room.

      Jack Rickard

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    4. Yes, the nature of these things is to make the decision the week before. Since that's how I do it, I understand the process. I swear I am NOT going, not going , not going......

      Then at the last minute - WHAT THE HELL - Let's go! Mad scramble to get plane tickets, hotel rooms not available etc. Human nature. You start to hear who all WILL be there and at some critical mass you want to go.

      Jack Rickard

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  8. Be careful using temperature as a measurement to calculate % change when it is really energy differences being compared. Fahrenheit and Celsius have different zero points, neither of which is at absolute zero. For example, 162°F to 204°F is ~25.9% increase, 72.2°C to 95.6°C is ~32% increase but using absolute energy units, the Kelvin (not degrees Kelvin, BTW), will give a truer picture. 345.4K to 368.7K is ~6.7% increase. Note however, that other factors such as ambient temperature and air flow would really need to be considered as it is the temperature difference between the comm and the surroundings which affect heat loss.

    Using the power numbers are a far better estimate of efficiency gains. My guess is that if the the motor were run at the same RPM for each case, which would introduce another variable (controller losses), that the power use differences would have been even further apart.

    This doesn't diminish the net results where none of the "intermediate" measurements matter when we are really interested in the boost in range.

    FWIW, I'm seeing a similar efficiency improvement in my Gizmo after installing a longer motor. I'm still dialing in the programming in my SepEx controller so I don't have final numbers yet but they look real good.

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    1. Results will vary for each persons setup. The test is valid and reproducible. Do the same for your setup and record the results. The results will not be the same as your tools are different and your motor is different and your brushes are different and your controller is different but you will see a significant change because the test is valid and reproducible. Check your temps any way you choose. But use the same technique each and every time to get results you can see and graph.

      How much different is your motor compared to the previous and was the motor change at a cost of $150 bucks or less?

      Delete
    2. I didn't say anything about the test being invalid. I said using degrees F or degrees C as a percentage change is not valid since neither scale has its zero at absolute zero. I even proved it by showing that each produces a different percentage change. That is all.

      Delete
  9. Latest Tesla Model S news....
    http://www.engadget.com/2012/05/22/tesla-model-s-crash-test/

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  10. Has anyone put the 9" Kostov motor head to head with the Warp 9? And are there Hellwig red top brushes for the Kostov motors?

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    1. I am hoping that Helwig makes brushes that will fit my GE and Kostov 11" (older style). Have not contacted them yet.

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  11. Andyj having another Eureka moment here.

    An electric motor is essentially a resistance in series with an inductor.
    This fed at a particular frequency gives what is called an impedance by producing a phase lag. It's effectively a resistance that varies when the latter values are altered.

    Summarise this with a higher brush resistance it's lose on, Voltage, heat, current, field build up rate, field position angle, field collapse rate.

    Never mind the other issues, are there differing resistances between these brushes to explain the heat generated?

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    1. or just micro arcing/resistance explains the heat? smaller arcs, less resistance, less heat? or is it too simple?

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    2. I think you're all over it Chad and it is about that simple. The loss goes as heat.

      Jack Rickard

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    3. Chad, I buy that too. Resistance is heat was my first consideration.
      This was on top of Google, a brilliant write up covering everything:

      http://www.maintenanceworld.com/Articles/Koenitzer/dc-motor-brushes-rotor.html

      A surprise note for Tim who lives in AZ.
      Humidity!

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  12. It is what it is!

    Looking at your data there are two things happening when you change the brushes. The Helwigs have less voltage drop which means their resistance is less. They also have less drag. With an unloaded motor there are only two places where the energy going into the motor ends up. One is as heat, the other is the load on the shaft from the internal fan which is moving air through the motor to remove that waste heat. The higher RPM with the Helwig brushes is indicative of the lower resistance since RPM is proportional to voltage. The fact that the temperature is lower with the Helwigs is another indicator. The increase in current seen with the other brushes indicates that there is more drag. Higher drag would also lower the RPM. So all this makes sense. Is it surprising that there is a difference caused by the brushes? Not really, but the amount of difference is surprising.

    This was a very interesting program! Thanks!

    Doug

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  13. Everyone is on the ball with the absolute basics.
    Time to get the maths book out and start thinking AC circuits.

    The DC is pulsing four rotor and stator coils via four brushes in series. No argument, more resistance heating for all to see with the softer brushes. What I'm attempting to describe makes it worse upon worse.

    Adding resistance in series to the coils creates a marked phase lag which in turn creates sparking, adding to the effective resistance and wear. It will also slow down the field build up and decay, so lower the power output. More than the effective voltage across the coils themselves should give.

    We'll also get increased brush wear by sparking heat) because the phase is out. This effect will become worse at high rpm as the impedance gets worse! The new brushes will markedly improve power and efficiency at high rpm.

    I do not believe for one minute the noted extra heat purely represents a 20% drop in efficiency. On DC it would imply a 20% extra resistance which I doubt.

    As a hobby sideline for years I've made quite a few high Q factor magnetic loops for radio ham use. These are similar in many ways. Resistance/impedance is the killer.

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  14. Jack, I think this thing could improve your show: http://youtu.be/6J9uRbjQGjY

    Unobtanium I'm afraid :(

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    1. Um, how is an Eddie Robot (that name just kills me! LOL!) unobtainium?

      Delete
    2. Jack,

      Another great show this week and your A123 packs are evoling nicely. What if you had a plastic shell made by a plastic molding shop and after filling, just leave the box as the outter cover? This would save you the time and trouble of removing the module from the mold and having to skim coat the outside of the module to make it pretty.

      Randy

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  15. Below is a link to American Molded Plastic. I have never used them but it may give you an idea of how much a box would cost to have molded.

    americanmoldedplastic@earthlink.com

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  16. Another great show for the week of 25 May. I was sorry to see the battery blow up.

    I noticed big changes in the sound of the motor as the brush tests went along. Maybe you could add a sound level meter to the testing procedure. They are not that expensive, heck even Radio Shack still sells them.

    When you take the measurements have the meter mounted in a holder so it doesn't move around. And also stand in the same place to keep the sound reflections consistent.

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  17. I know you proscribe the Cycle Analyst, Jack.
    Everything you were recording would of been automatic with one of these, to a laptop.

    All apart from heat.

    I did wonder about the knife switch. What if you got rear ended by an armadillo or Marty McFly thought it was a handy tow loop for his skateboard?

    ReplyDelete
  18. Hi Jack,

    I'm sorry to see the sad remains of your battery. Might I suggest using Valery's DIY 10000 kw charger for this job. I know it's overkill but I think it's programmable for any size pack and voltage.

    ReplyDelete
  19. Required this for those pneumatic bellows:-
    http://secure.transtronics.com/WW12D100P55-21.htm

    Joking aside. It was sad. For all your gear. Warn us, what were you using that did not limit the voltage?

    ReplyDelete
  20. Hey Jack,

    If you integrate RPM with time, you would have (approx.) the total number of revolutions turned by the 129 AH spent in each case. This might be a better analog for range than simply the number of hours 129 AH lasted, and you already have the data.

    Mike Kaindl

    ReplyDelete
  21. Hey Jack,

    I'll do the back-of-envelope math for you

    H60: 2652 RPM (avg.) x 216 min. = 572,832 revs.
    H8: 2053 RPM (avg.) x 181 min. = 371,593 revs.

    That's a 54% improvement with the H60's. If your car weighed zero, had zero frontal area, zero rolling resistance, etc., etc., it would have gone 54% farther.

    Mike Kaindl

    ReplyDelete
  22. Wow! Add that extra 54% to the 88% efficiency!

    ReplyDelete
  23. Here's a thought... Instead of these expensive multi-use molds (that seem to end up being one shots anyway), how about just making the mold out of cardboard. Coat with release agents and peel off.

    - Doc

    ReplyDelete
    Replies
    1. I thought the original mold with plexiglass on both sides worked pretty well.

      Delete
    2. Learning the valuable lessons from A123's unserviceable monoliths:-

      Cast the cells!

      Sorry guys, I just don't get it.
      For one failed $30 cell, a $1000 pack gets binned.

      Delete
    3. http://www.airloy.com/category/home/

      "Airloys are a new class of advanced engineering materials that combine the strength of conventional plastics with the low density and superinsulating properties of aerogels...Airloys are typically three to ten times lighter than conventional plastics and ceramics and are available in densities ranging from 0.01 to 0.9 g/cc.

      Delete
  24. Great show as always.

    To avoid ticking off our Scotishe cousins, "hebrides" is prounounced "heb-RID-ees" rather than "heb-RIDES". Just like most hebrideans would probably say "miss-OW-er-aye"

    ReplyDelete
  25. Oh, and "Scottish" is not spelt "Scotishe"

    ReplyDelete
  26. Separated by a common language. Even amongst Brits! Hebrideans speak fine. Glaswegians? Translation comes after "eat pants 'o heavie" whereupon you find the man with the smelly bag between his feet is offering you a selection of road kill for a few more rounds. Beats me how salmon ends up as road kill.

    JR suggested email to correct the panic beeping on the JLD-404. I thought up two options:
    Pliers. (You know the griff).
    Remove the instrument.

    Whiskey!
    TV presenter Alan Titmarsh done a great series "British isles a natural history". Here he demonstrates and explains how our incredibly varied geologies release the different types of waters for our whiskey. 30:55 in.
    http://youtu.be/qhx17WCbUKA

    A regular beer monster on the wrong side of the bar. Watch his eye's. haha.

    ReplyDelete
    Replies
    1. AndyJ...can you imagine tasting all of those Scotches that were featured in the BBS video, and a lot of the differences were from the water filtered through the British rocks. You British have a rich culture indeed.
      I am sure Jack as well would appreciate what you British have done for the "culture" of creating a fine Scotch.
      We all can appreciate discussing the origin of fine Scotch, but you know what really really want to know is....
      Jack, What is happening on your Escalade build?
      Mark Yormark

      Delete
    2. Nothing that can't be fixed with a quality fungicide.

      World C02 levels are dropping! They put it down to us holding our breath.

      Delete
  27. completely off topic, but an interesting perspective I read the other day.

    --------------

    Here is another intersting perspective on all this infrastructure stuff.

    There are 47,182 miles of interstates in the US:

    http://en.wikipedia.org/wiki/Interstate_Highway_System

    If we were to install a Fast Charger every 40 miles on every interstate in the US it would be aproximatly 1180 fast chargers. If they all cost the current $50K a piece, that is $59 Million dollars for that infrastructure.

    ------------------

    http://strangemaps.files.wordpress.com/2007/02/fullinterstatemap-web.jpg

    If the DCQC chargers are $20k each then a $50k installed cost is not unreasonable, $59 million is a drop in the bucket for creating an infrastructure.

    food for thought

    ReplyDelete
    Replies
    1. I sure like this new math. I'm going to steal this and share it around. This is REALLY the key to the electric car range problem, fast charging.

      But I too would have guessed a much higher number. $59 million seems paltry. They already have $110 million programs to put Level II chargers where no one will EVER use them.

      But a fast charger every 40 miles - that's cool. To enter/exist, I bet it DOES cost more than that, but still.. A paltry amount.

      Delete
    2. But how few EVs could the 1180 fast chargers service? The $59 large would not provide a developed alternative infrastructure, though the money spent would be justified if but for raising awareness and backbone modeling.

      Delete
    3. Kind of misses the point Perin. Not only would it provide an infrastructure, but initially a largely UNUSED one. It removes the barrier to moving electric cars around the country. There is no infrastructure because there are no cars.

      For $59 milion, anyone can drive anywhere in the country in an electric car. And they will. At the point where it is overburdened, truck stops can add fast chargers for little more than the cost of their existing pumps, and their business is in twinkles anyway. They would do so were there cars needing them.

      So this is an ice pick in the egg - in a classic chicken vs egg scenario.

      FIrst they stand empty.

      The few electric cars there are discover them.

      It can easily service THAT demand.

      Once people learn they can travel coast to coast, more electric cars are sold.

      As the road going population builds, the existing 166000 gas stations become attracted to the profit motive.

      Done.

      It is INDEED salutary in the beginning. But WOULDe in fact enable travel by the very few of us that actually have cars.

      Even our cars would have to be enabled to do fast charging. But it would largely be worthwhile.

      Jack Rickard

      Delete
  28. completely off topic, but an interesting perspective I read the other day.

    --------------

    Here is another intersting perspective on all this infrastructure stuff.

    There are 47,182 miles of interstates in the US:

    http://en.wikipedia.org/wiki/Interstate_Highway_System

    If we were to install a Fast Charger every 40 miles on every interstate in the US it would be aproximatly 1180 fast chargers. If they all cost the current $50K a piece, that is $59 Million dollars for that infrastructure.

    ------------------

    http://strangemaps.files.wordpress.com/2007/02/fullinterstatemap-web.jpg

    If the DCQC chargers are $20k each then a $50k installed cost is not unreasonable, $59 million is a drop in the bucket for creating an infrastructure.

    food for thought

    ReplyDelete
    Replies
    1. Here's food for thought.

      Renaults system of battery leasing and their cars can do a battery swap in 3 minutes.

      As fast as filling up your fuelled motor.

      Delete
    2. I'm not a fan of the battery swap model for consumers. Great for delivery vans and taxies where one company owns all the batteries. For me, I take great care of my equipment. I am gentle on my EV battery, and I only need to take a long trip once a year. So my gently used battery then gets swapped for a pack that has been abused and now I've got a terrible battery in my car. How do I get a good one back? Who is responsible for this abused pack? Renters are typically not gentle on their equipment and so the lease rates will be high to cover all the abuse. Lots of obstacles. I'll stick to owning my pack. I was just caught off guard by the low cost of infrastructure for the US. Even if you nearly double the number to $100M it is a lot less than I had in my mind and really not that expensive in the grand scheme of things.

      Delete
    3. Buy over lease care.. I agree!
      But, another 80 miles down the road you have another battery. Any packs on charge at the garage that falls below capacity will have to be serviced, it's no loss to them. Renault pay, leasings not cheap!

      You can bet your bottom dollar any Gov't funding will be priced for an oligarch to make lot$$$.

      Private is best. A free recharge while you pamper instead of paying for fuel.

      This sells me.
      http://www.teslamotorsclub.com/showthread.php/7966-A-weekend-in-the-English-Lake-District-with-a-Roadster-UK-HPC-Zero-Net-and-OVMS

      Delete
    4. One way to lease batteries and wind up with the one you started with is to lease "trip batteries". You put your original battery in storage and lease a battery for the trip swap it out along the way, when you get back home you return the rental and put your original battery back in.

      Delete
    5. I'm sure the friendly local swap shop would return your fave pack all charged if you asked nicely.

      Delete
  29. the 100+km/h electric handicap scooter again in case you missed it because Jack deletes my comments
    http://www.youtube.com/watch?v=JEAtaja2KGY

    ReplyDelete
    Replies
    1. Jack deletes? Maybe one of Santa's little helpers do.

      0~60, 7 secs in a spasschair for the handicapped. Most fun. Beat that Mr. Rickard. lol

      Delete
  30. Until it gets removed, my comment before was, its a waste and of no use. You SPAZ around the lot for a minute then it becomes quite boring. It was boring to WATCH before. Nothing has changed. Why anyone would anyone waste such money and time on a SPAZ mobility cart is beyond me.

    Dan, you still don't get it do you.

    ReplyDelete
    Replies
    1. I'm born, I laugh, I'll die.
      While in the laughing bit; I get it :)

      Delete
  31. On a positive note, I hope:
    Unobtainium?, They claim 12 months more to market.
    www.prietobattery.com

    ReplyDelete
    Replies
    1. Please try again later.
      Apache/1.3.42 Server at prietobattery.com Port 80.

      perfecte deficiat

      Delete
  32. Prietobattery: thank you for pointing it out. One of a number of startups playing with nanotechnology, lithium sulphur or lithium air. One of them may become the Google of 450 watt-hour per kg/100,000 cycle batteries. Morgan Crucible signed an agreement this week with Boston Power for development of cells using Morgan's new anode material (encapsulated nanotube). I don't bet, but if I did I'd have a flutter on Morgan before prieto.

    ReplyDelete
    Replies
    1. John:
      I'm sure that Prieto has much testing to do in order to prove the concept. With all this hectic activity, perhaps someone will break through the stone walls of battery research into the happiness of "Production Nirvana." (Ha)

      Delete
  33. I just registered for EVCCON, see all of you there!

    ReplyDelete
    Replies
    1. Getting in by the skin of your teeth I see. Welcome and we shall see you there. Bringing a vehicle?

      Delete
    2. Only if Hertz or Avis rent Leafs. The Army has to keep me in one spot long enough (and with a short enough work week) to make it possible first.

      Delete
    3. Great! Hope to see you any everyone else there...

      Delete
  34. It's been a week now, and no one has mentioned Brian's little "hiccup" this week at 1:36:00 or so. It came out so unexpectedly that I nearly spat out my coffee laughing and watched it over and over. Brian is probably wishing his microphone wasn't working this week.

    ReplyDelete
    Replies
    1. Hiccups. Awww, bless you Brian. Our language is full of it. "Excuse my Anglo-Saxon".

      http://www.belfasttelegraph.co.uk/lifestyle/features/the-uks-rudest-places-from-bell-end-to-wetwang-15148383.html

      Jack 'n Brian are going to love it here.

      As usual, the last line is best :)

      Delete
    2. Dang nabbit I missed it the first time through but Brain's reaction can't be missed! As always love the show.

      Charlie B.

      Delete
  35. I got a feeling the Escalade will be rolling soon and I can't wait. What I find most exciting is we don’t know what exactly it is capable of doing. And, Jack may be building a very light vehicle. Both are designed to be functional conversions. I think we can learn a lot sometimes be contrasting extremes, rather than aiming for a more realistic middle ground. Thanks Jack.

    ReplyDelete