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  1. T

    Molicel P42A, Sony/Murata US18650VTC5D in 14s5p battery packs sounds like a good deal?

    That's BQ76940, a fairly popular BMS IC from TI. https://www.ti.com/product/BQ76940
  2. T

    Repaired my Grin pack, I think...

    Did you inspect the cell groups while you had it open? The voltage you measure at end of charge depends on the charger and BMS specs, but 83.9V is very close to 4.2V per cell which is pretty much as high as you would want to charge that pack.
  3. T

    Mid drive motor on swingarm

    You also lose the drawbacks/benefits of chain tension affecting your suspension. The bike ends up acting more like a very torquey but somehow lightweight hub motor is propelling it. There are plenty of builds here with a mid drive motor on the swingarm. Go for it! Neumotor 8057/75 middrive...
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    Observed trials bike designing

    Ok I'll ignore the implementation of virtual clutch for now. I'm interested in it one day being implemented, but that's not for this thread. So how do we implement a virtual flywheel. Below is my first pass at how to do it: A virtual freewheel controller uses the throttle signal and motor rpm...
  5. T

    Observed trials bike designing

    Yes, I wonder if an electric controller could be responsive enough to get rid of the clutch. Yes a tone to indicate the rpm of the flywheel would be essential. It could increase in pitch and volume as the flywheel gains energy. I think it would help if we start focusing on the specific units...
  6. T

    Observed trials bike designing

    I'm pretty sure I understand how clutches work. The clutch lever gives you control over the torque that the clutch is transferring from the flywheel + engine/motor to the rear wheel. With a physical clutch, it does this by controlling the pressure that squeezes the plates in the clutch together...
  7. T

    Observed trials bike designing

    I think a virtual flywheel controller could be implemented with only knowledge of throttle position and clutch position. You track the angular velocity of the "flywheel." Throttle inputs add energy to the flywheel while clutch inputs take it away (provided the flywheel is spinning fast enough to...
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    Observed trials bike designing

    @bikerpete I haven't read the entire thread in detail, but it seems like in some posts you want a virtual flywheel and in other posts, it seems like you think a physical flywheel is needed. Are you interested in trying out both methods? How much continuous power and top speed is needed for a...
  9. T

    Understanding gear reduction on a mid drive vs rpm/v

    The wheel torque is the same in both setups, but the half Kv motor with half gearing has to put out twice the torque. As @Hummina Shadeeba said, motor torque is constrained by its size and design - the way it is wound doesn't affect the torque capabilities very much. To put out twice the torque...
  10. T

    30-40 amp capable charging for my ebike

    Make sure your charger can accept 208-240VAC. Then buy one of these to charge at J1772 stations. You're not going to be able to charge at a Tesla supercharger. For Tesla destination chargers, you could buy a Tesla to J1772 adapter and plug that into your J1772 to Nema 5-15 adapter, but that's a...
  11. T

    Modular, Multi-Platform, 300A ESC

    Thanks for the replies. My boards shipped yesterday, so hopefully I'll have some working controllers in the next couple weeks, although mine are going to look a lot different from normal MP2s.
  12. T

    Modular, Multi-Platform, 300A ESC

    @owhite I just ordered 5pcs of the 1.11 F405 pills, and jlcpcb is complaining that the outline of the board is "shaving the trace" and want to expand the outline by 0.4mm. Have you ordered this version of the board yet?
  13. T

    1 Cell Inverter Project

    For a proof of concept, couldn't you use any 100A capable ESC with a 12V boost converter to supply the gate drivers and MCU? It wouldn't be an optimized 1S ESC, but it could probably work. Or you could run your solid slot motor on a higher voltage and just let the ESC limit the current to the...
  14. T

    'lightest.bike' 1.7kg 1000w mid drive

    I've seen a couple comments about the 90Nm effective/equivalent torque, and I wanted to explain what I think they mean. Normally a mid drive motor system drives the chainring directly which is 30-40 teeth. The bikee lightest system drives the chain using a tiny little 10 tooth sprocket. This...
  15. T

    Laser cut silicon steel laminate?

    https://endless-sphere.com/sphere/threads/building-a-motor.113006/post-1686798 Protolam has been mentioned on this forum before.
  16. T

    Portable programmable CAN Module

    You could use an Adafruit RP2040 CAN Bus Feather.
  17. T

    Grin's rear all axle motor!

    Don't you need to anchor the torque arm to the seat stay since that's where the axle is mounted?
  18. T

    Outrunner left side mid-drive conversion

    Thanks for posting your bike! Your motor mount is interesting. Hopefully it stays put. The left seat stay on my bike does not allow me to mount my motor there since it interferes with the chain. Hopefully the hobby robotics chain works for you. I bought my chain and chain tool from Swyft...
  19. T

    Field Weakening, help me understand

    I don't think it is 100% a myth. At normal temperatures, field weakening is usually not strong enough to permanently affect motor magnets, but higher temperatures make the magnets more sensitive to the opposing field that field weakening generates.
  20. T

    Single stage RC left hand drive

    alpaca123, what motor did you end up going for?
  21. T

    What’s the math to figure torque based on stator size?

    Yep that's the rough way to do it. 1.45x more surface area and 1.45x greater leverage. The 1.45x bigger surface may also be able to transfer 1.45x more heat for the same temperature differential, so you could multiply by 1.45 again if you're willing to burn more heat and looking for continuous...
  22. T

    Single stage RC left hand drive

    The ebikes.ca simulator is good for comparing setups and seeing how a motor will perform. I set up a sample comparison between a 10:1 geared 160Kv motor and a grin v2 hub motor. Motor Simulator - Tools As far as motor size goes, you're in the right ballpark with an 80xx motor. To comfortably...
  23. T

    Single stage RC left hand drive

    What speed and power level are you targeting? The baserunner has similar phase current to the cheap focer 2 I am using, so you'll get similar torque if you match my gearing and motor Kv (160 for my motor). If you want more torque, then you'll need a bigger motor and lower Kv or a larger...
  24. T

    Rewinding a QS 273 motor

    One thing I remember thud doing on his rewinds was setting up a multimeter on beep continuity mode then connecting one probe to the stator and the other probe to the wires he was winding with. That way he would immediately know if he had pulled a short and could go back to rearrange the wires or...
  25. T

    Thoughts on Paramotor parts list

    Have you seen the openppg sp140? https://openppg.com/shop/paramotors/openppg-sp140/ They're using a little bigger motor than the 12070, something around the M40 from MAD which is ~15065. On the esc, 250A is wishful thinking for that motor, and 380-500A is trying to take into account the...
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