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  1. T

    DC in Tesla Level 2 Charging?

    Interesting idea. It might work. Not sure if the car charger will care if it is getting DC instead of AC, but I suspect not. I don't really want to try it on my own car though. You might be able to look at some of the numerous Tesla teardowns on Youtube to find the charger topology.
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    Chevy Bolt first drive

    But if you are paying CA power prices, then you would also have to pay CA gas prices.
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    Best Mid-drive Motors in 2021

    Exciting! I have been thinking of making something like this for a while, so it is cool to see others are doing it! Left hand drive definitely addresses the problem of reliability on the pedal side of the drivetrain. FYI I have fit a "dual-drive" system on 135mm rear spacing, but it does limit...
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    Fuse melting...but not blowing on Power Wheels

    30A mini fuses are going to run pretty hot. I would increase the fuse to a larger package such as ATO if you can. If you want to stick with the mini, you should be running at least 12AWG to try to move the heat away from the fuse.
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    Rough draft of a 6FET power stage intended to be part of a larger controller

    Let's say we are working with a 5uH motor with a 100Vdc bus. v=Ldi/dt so di/dt=100/5e-6=2e7 A/s Divide this by 100000Hz switching frequency, and we get 200 A/switching cycle. If this is a 1000A motor, then 200App ripple on top of that is probably not too big a problem. Drop the switching...
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    40kW paramotor project

    I would probably just use a Curtis if I worked for them. Open PPG is using an APD esc in the SP140 kit.
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    Left side drive: what's current?

    I think mayyybe 2x peak torque is possible with some significant changes to the motor, but anything beyond that is going to be quite difficult. Putting "more/better magnets" will only increase torque so much. As you said, there are limits. These limits will arrive much sooner than even doubling...
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    Left side drive: what's current?

    The bold part is 0% true. The specs that Alien Power Systems has provided on their website are completely wrong. There is no way that any 6374 motor wound to only 30Kv can do 80A continuous for even a short time. The 2800W rating is going to require at least 200V of input before you have even a...
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    Left side drive: what's current?

    You just said you needed a small front pulley, and then later you are criticizing how small the 25h sprockets are. The smallness of the 25H sprockets is a feature! What motor are YOU thinking of? For me, I used a 6374 motor initially since it was cheap while I tried out my drive system. I am...
  10. T

    APL's Pressure Contact Battery box

    Why not dimple the copper sheet? I did it with a 3d printed jig, a 1/4" standoff, and some channel locks.
  11. T

    What's the c-rate of this cell?

    True. While the cell can do 10A, it won't be very happy doing so. The spec says the fast discharge rate is 2.5A. I would aim to stay around that number if I were using this cell.
  12. T

    What's the c-rate of this cell?

    Yes you are correct. The continuous discharge rating is 10A which is equal to 3.846C.
  13. T

    DD Motor

    I guess you're still looking for feedback, but what kind of motor do you think you can improve on? Just a halbach array, how much will it help? I think it reduces weight a bit since you can use a little less magnet and don't need back iron although you still need something stiff to hold the...
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    Chevy Bolt first drive

    Oops I just bought a 2022. I thought they had fixed the problem causing the fires. Oh well. I really like the car, don't have a garage anyway, wasn't planning on charging to 100% for daily use, and it hasn't caught fire yet.
  15. T

    How about a 3D printer section?

    I have an Ender 3. I like PETG a lot. Been buying it from Atomic Filaments. I don't do anything special for storing it, and it seems to work fine. I second the larger nozzles. For the structural stuff that I print, a 0.8mm nozzle works great and is so much faster. Also second the PVA bed...
  16. T

    at what point is gearing no longer helpful?

    Why do you need a custom frame for this? What about a fixie frame with horizontal slotted dropouts for tensioning the chain? Not that I'm recommending you go 40mph on such a frame (neither a fixie frame nor the one pictured in your post). Is it just to put the motor in the middle of the seat...
  17. T

    I cant enter any threads, get "SQL ERROR"

    Thank you neptronix!
  18. T

    at what point is gearing no longer helpful?

    Why do you want an eccentric bottom bracket? Normally they are used to tension a chain on a hardtail, but it won't work on a full suspension bike unless the rear pivot is concentric with the motor or jackshaft which is very uncommon. As far as the optimal frame design, I'm not sure about all...
  19. T

    at what point is gearing no longer helpful?

    I think that green frame will have pretty bad suspension characteristics from the chain tension pulling on the rear wheel. For minimal suspension effect, you want the chain to pass through the pivot point. As far as when eddy current losses start to get unreasonable, user "thud" said 80xx...
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    Mid-drive using bb as jackshaft w one-way bearing?

    The problem with doing a 12:1 gearing this way is that your jackshaft will be spinning at a couple thousand rpm which means you won't be able to add anything with your legs since human legs can only do about 100rpm.
  21. T

    Forum name

    Why do you want the chainrings on opposite sides of the bottom bracket? Normally they are on the same side of the bottom bracket. Example pic below of a tangent drive.
  22. T

    Giant Trance Belt drive with MESC @ few kW

    Really cool. For a bigger motor, maybe something like a 12070? I know they're expensive, but MAD's M30 motor and the T-15 should be pretty powerful. If you want to go really cheap, you could get a hoverboard motor and adapt it to fit your bike, but it needs a rewind to make good power at a...
  23. T

    what is cogging torque?

    Roughly yes. A closed slot stator has a different magnetic path compared to the open slot motor, so the eddy current losses may be a little different, but for the same size and similar tooth design, they should be close. No it should be similar. It sounds like you have these motors. Perhaps...
  24. T

    what is cogging torque?

    By slotless motor, do you mean closed slots? Look on page 19 of that paper. It says "closed slots like in Figure 16 (c) can be a great solution since there is a better flux path through the stator teeth" which means there is less variability in the reluctance of the stator which means the...
  25. T

    what is cogging torque?

    No cogging is not a loss of momentum or energy. As we've said again and again, the force as a magnet approaches a stator tooth and as it leaves the tooth is equal and opposite. That is the definition of cogging. No cogging is not an iron loss nor a hysteresis loss. It is not a loss. It is a net...
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