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  1. roller

    Job Posting (Seattle, WA): Battery Tech

    Howdy E-S (if there's a better place to point out job postings, lmk) Here's a listing for Amazon delivery drone in Seattle; Associate's Degree level, hourly position; working w/ Li batteries/cells. It's a hands-on tech position on the R&D propulsion team. If you think you and the position...
  2. roller

    College Class electric tadpole trike build thread

    Dr. Ted ~ if the course is a success, and looks to continue or "grow up" the EV food-chain a little bit, you/faculty should check out Switch Vehicles : http://switchvehicles.com/ http://www.theswitchlab.com/ They provide kits, but also specifically curriculum for EV building courses.
  3. roller

    Mysterious degradation in performance - Lyen/Transmag

    Looks like you guys are on-target with over-heated magnets. The definitive test (particularly since you have 2 "identical" motors) is NLS (no-load speed) test. Same supply/controller, nothing (significant) attached to shaft .. . record full-throttle speed /volts / amps. At NLS, each should be...
  4. roller

    Transmagnetics 5 / 5.25 inch 3kW motor info +reduction ideas

    Howdy Dan ~ you can clamp the can - but you should also catch a notch in the face, to resolve torque. the clamp may allow the housing to spin . . . Also -- unless clamp is wide, some flex may allow the shaft to be not parallel to the axis of your wheel. endcaps are held 90% by friction...
  5. roller

    First hub motor rewind

    I would vote not to "hope" you "fixed" the problem, but to make more measurements and understand better what is happening. It looks like you are cutting the interconnects (crossovers between poles of a given phase), and if the charred wire is a strand of an interconnect, then it certainly...
  6. roller

    Transmagnetics 5 / 5.25 inch 3kW motor info +reduction ideas

    Personally - I wouldn't even consider the fan "consumption" compared to what it provides: Peak power is a function of the motor structure ( copper/steel/mags, {controller, yadda, yadda}), but Continuous power (as % of that peak) is a function of the package (vented vs. sealed, inrunner vs...
  7. roller

    Transmagnetics 5 / 5.25 inch 3kW motor info +reduction ideas

    cool, Neptronix. Just make sure your brakes are up to snuff on your bike! This motor structure (in a sealed package on the Jackalope) had me going about 45mph with 4.4:1 GR on 20" wheel. Thread note: This is the Transmagnetic 532 ( "5" inch {really 5-1/4" stack OD}, 32mm stack length)...
  8. roller

    Transmagnetics 5 / 5.25 inch 3kW motor info +reduction ideas

    SpinningMag - "Y" connected Nep - if your controller uses a "normal" logic, here's a correlation: phase :::::: Halls Black -- A -- green Green -- B -- yellow Yellow -- C -- brown ::::::::: +5 -- red ::::::::: grnd - black ::::::::: temp -- blue
  9. roller

    Transmagnetics 5 / 5.25 inch 3kW motor info +reduction ideas

    nep - -- I could probably get you a seat on a Chinese assembly line, if you wanted . . . you can dis/assemble all the motors you want! --- go easy putting that rotor back in stator -- it's got some finger pinching pull. We do it with a fixture so mags can't hit the steel. --...
  10. roller

    Arlo's power stage Leaf controller runs and drives page 103

    props, Arlo -- no small feat. Surviving test rides is very satisfying.
  11. roller

    Comparing motor specifications

    don't know how it would relate to motor constants . . . but a nice generic motor metric would be the ratio of (real) continuous power (out) to peak power (out): Pcont/Ppk The closer to 1, the more "useful" or "optimized" or "effective" the thermal system is. As your efficiency or cooling...
  12. roller

    Comparing motor specifications

    it holds (and is intended) for variations upon a given lamination/stator (tooth geometry). The magic "40" is for a Transmagnetic 4", 12/8 pole motor only, of standard lam mat'l + thickness. But with that knowledge, I know what saturation is for all of our 4" motors of any winding or stack...
  13. roller

    Magnetic field detection / measurement

    could only recommend moderately against Samsung T959V (aka T-mo 4G) . . . RAM chokes on it's own bloatware . . . consumes 80% at idle (of 323 available of purported 500 MB). but at least it can run Max Mag.
  14. roller

    Magnetic field detection / measurement

    For Android users -- https://play.google.com/store/apps/details?id=com.maxcom.magdetector Max Magnetic Field Detector cheap (free?) app to use your phone for measuring mag fields. Very sensitive (micro-Tesla). Use to compare magnets (neo from a distance!), or suss out saturation on your...
  15. roller

    Building a triple stator axial flux motor

    Iron = torque density torque density --> power density --> performance efficiency --> material efficiency = lower cost, higher performance . . . Thanks Steel! What you lack in steel, you have to make up for in magnet and copper. I'd rather pay for steel. 70% or so of a motor's losses are...
  16. roller

    Comparing motor specifications

    toolman -- a thought about saturation that may be easier. . . (unless building 500A supplies is something you do in your sleep): stator field/saturation is proportional to (A*t/mm) = "phase (pk) amps x coil turns per mm of stack length" . In some of our early motors, this was the magic...
  17. roller

    Comparing motor specifications

    toolman - thanks for the curve -- that's pretty impressive stuff. What's changing between the 10 runs that causes differentiation? (motor/windings/voltage/temperature/ . .? ) Would be nice to know corresponding amps/efficiency along the curve . . , but I get that this is a wheel dyno...
  18. roller

    Building a triple stator axial flux motor

    you could certainly do that, Miles. . . long flat strip wound on the screw before the copper . . . could use the existing winding jig. There you go, Lebowski, take it apart. I'm inclined to think that laminations are and improvement, but not 'required'. Or, that the net gain of laminations...
  19. roller

    Building a triple stator axial flux motor

    steel core will also give you more thermal stability (inertia) . . . as it can absorb some coil heat which acrylic can not . . .
  20. roller

    Building a triple stator axial flux motor

    subscribed - Lebowski - I didn't find comment in this thread . . . can you muse on your motivation for a "coreless" approach on the stator ? Seems it would have been almost as easy to wind your coils around a steel hub, instead of acrylic . . . though this gives you no "back iron" per se, it...
  21. roller

    Comparing motor specifications

    Miles ~ (from the text) "This method may not get you to exactly the correct “house” but it will put you on the correct “street”." :P I've seen two approaches to Km in this thread/paper, "defined as" : Km =: Kt / (R)^.5 but also: Km = T / (Pin-Pout)^.5 where T may be written Kt * A . ...
  22. roller

    Comparing motor specifications

    toolman: Calculation -- if you happen to know your turn count + wire guage + stack heighth, you may be able to suss out a field strength per amp [Tesla] through modelling/geometry? Your silicon steel will saturate around 1.4 Tesla. measuring saturation -- "officially" a straight ahead motor...
  23. roller

    Ariens 1.7 HP Lawnmower Motor = 4" Transmag 48V

    while I can't deny your results (coil short), flathill, I can see there are flaws in your logic (motor suckage). Examining your logic -- does it surprise you, that a motor (obviously designed/built for a spec application {which happens to be 600W cont} . . . 1300pk =>"1.7HP" customer claim})...
  24. roller

    Field Oriented Control using dsPic33

    ditto.
  25. roller

    motor waveform symmetry

    all that said -- if you're *measuring* back-emf on a motor (spinning the shaft open-circuit, no controller) and seeing some funny asymmetry, there's probably some coil short or cross-wiring at interconnects . . . or if seeing it only "in-circuit" with a driver, there may be funny stuff going on...
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