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  1. P

    Ring gear / drone motor Ebike prototype

    @marka-ee : yes - also be considering that very long belts are not available for so specific length you might need... I also tried to use idler roller directly against the little pulley to prevent belt teeth to escape the pulley, but this might put some more wear on the belt for some reasons, I...
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    Ring gear / drone motor Ebike prototype

    The idler roller on the belt increases its curvatures and consequently its losses as far as I understand it.
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    Ring gear / drone motor Ebike prototype

    Yes, that were reasons for me to try the large ring gear instead belts. Along with the easy disengagement of the motor. But still noise problem and probably long term wear due to dirt might make it stay an idea more than my everyday motor. Possibly some will reuse and improve the "ring in a...
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    Ring gear / drone motor Ebike prototype

    Yes, the AT5 belt would required high initial tension so that it does not slip on the small pulley (the large pulley ratio makes the teeth only engage in a quarter of the small pulley - unless I added a belt tensionner - which I did, but at the expense of higher power losses it seems. Belt was...
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    Ring gear / drone motor Ebike prototype

    10mm thick ring was choosen to reduce load on the teeth. The idea was to push approx. 100N of tire force to compensate for most of the bike+me+trailer load weight in a 10% slope. That's about 120N on the ring teeth, and assuming that it is spread on 5-10mm² of tooth area, make up to 24MPa of max...
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    Ring gear / drone motor Ebike prototype

    Forgot to mention that you need to be quite accurate in the rim internal diameter measurement, so that the FR4 ring will fit nicely. Also milling the spoke slots needs calculation, even when the 2 FR4 layers are thin, making 1mm diameter difference, leading to 3.1mm more on the circunference...
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    Ring gear / drone motor Ebike prototype

    The purpose of the intermediate ring is convert high gear module to a lower one, which makes it possible to use a smaller diameter gear on the motor, and in turn to achieve a higher gear ratio (near 20 on a "single" stage). The smallest module 2 gears have 12 teeth only and a somewhat larger...
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    Ring gear / drone motor Ebike prototype

    I use T-Motor P60 170kV. It should provide more than 1kW at higher speeds, but currently very limitted by teeth escaping the ring gear contact - I need to improve this. Probably a higher gear module for the large ring would have helped.
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    Ring gear / drone motor Ebike prototype

    Thks ! The main ring gear was cut in 2 parts of 5mm thick FR4 using 1.5mm diam end mill and then glued one on top of the other to make it 10mm thick. Then I milled 0.5mm thin FR4 sheets (3 parts per ring) with slots to accomodate the spokes positions and glued two layers around the 10mm ring...
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    Ring gear / drone motor Ebike prototype

    For those interested in low weight motors for Ebikes, I've used a drone motor (P60) and a (mostl likely) innovative gear reduction using : - a large ring gear (module2) attached to the rim - an intermediate external/internal freewheeling gear - a spur gear gear module 1 connected to the motor...
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    VESC Open Source - Android App Features?!?!

    @j3tch1u: did you start getting some results on this bluetooth connection ? I'm still looking for an Android based display (mostly to check battery state of charge) and logger for VESC. Can you post what your code if you think it might be reusable, at least the bluetooth part ? Thks.
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    VESC Open Source - Android App Features?!?!

    I think your initial value should be 0 for CRC, not 0xffff.
  13. P

    VESC Open Source - Android App Features?!?!

    CRC calculation starts from the data byte (3rd byte of the frame). For instance, only the 04 byte is used in 02 01 -04- 40 84 03 frame. You can use the following site to check, line CRC-CCITT (XModem), input type hex, just enter 04. http://www.lammertbies.nl/comm/info/crc-calculation.html So...
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    VESC Open Source - Android App Features?!?!

    The returned packet (seen from the PC) seems ok (size, start, stop, stable values..) I didn't really check the content. I tried bldc video logger, but it failed to open my Bluetooth serial port (possibly not waiting long enough).
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    VESC Open Source - Android App Features?!?!

    I used https://f-droid.org/wiki/page/ru.sash0k.bluetooth_terminal. Just for testing. The extra 00s probably due to a bug as you mention (no one would know until I scope the data) Probably we can reuse some of the sources ? https://github.com/Sash0k/bluetooth-spp-terminal. Except the comments...
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    VESC Open Source - Android App Features?!?!

    Using VESC firmware 1.6 and HC06 (=BtBee from iteadStudio), I could communicate with a PC via bluetooth. VESC application set to ADC + UART (in bldc-tools) First, at 9600 bauds setup the HC06 for 115200, sending AT+BAUD8 (upcase, no CRLF), you receive OK115200 (this requires a USB serial...
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    VESC Open Source - Android App Features?!?!

    Hi j3tch1u, If I understood well, you managed to get a response from VESC using a terminal program on a PC connected via bluetooth to the HC06? Now did you try an Android bluetooth terminal freeware to check if it works using the same frame ? With your implementation, possibly you could try...
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    VESC Open Source - Android App Features?!?!

    Hi, 02 01 17 62 D6 03 02 01 04 40 84 03 : this is actually 2 frames. From the packet.c file in bldc-master sources, the first frame is 02: start 01: length 17: data 62 D6: CRC 03: stop The datatypes.h gives Communication commands typedef enum { COMM_FW_VERSION = 0, COMM_JUMP_TO_BOOTLOADER...
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    10S custom skate ESC: testers wanted!

    From the datasheet, the DRV8302 Gate driver supports up to 200kHz switching frequency with Qg(TOT)=25nC or total 30mA gate drive average current. The auirfs8409-7p has 305nC total gate charge at Id=100A and Vds=20V (so a little more for a charged 6s). vs 236nC for IRFS7530 at Vds=30V. From...
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    Belt slip stopper, idea.

    I think the belt slip stopper idea is more efficient when using timing belts, because you hardly need any pressure of the roller on the pulley. Pressure will build up when torque is applied and the belt teeth want to escape the pulley slots. I use the slip stopper for 2kW motor with 1/17 gearing...
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    Using a mosfet as a switch?

    On my VESC, I measure 18.8mA idle current (on 48Volts battery) (VESC only, with just a 10kOhm potentiometer as a command). This current seems to be higher than the long term current reported by Marcin (4.4mA average on 6s). It might be possible to reduce the idle current using EN_GATE on...
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    Opensource Remote / BMS / BEC

    Yes, the idea is to avoid the adapter. I imagine several people use 2x 6s and the more adapters, the more issues. So it was just a proposal for you to modify the PCB to support both options, but it does not seem so easy to do.
  23. P

    10S custom skate ESC: testers wanted!

    I like the idea of using one shunt only. I don't think it removes the FOC possibility since you can reconstruct the 3 phase currents as in Microchip note AN1299 : http://ww1.microchip.com/downloads/en/AppNotes/01299A.pdf Otherwise, probably taking 3 samples each time, and using a median filter...
  24. P

    Opensource Remote / BMS / BEC

    @fuelre: would be nice if the BMS could handle both 1x12s or 2x6s battery connectors. It might be not so easy to modify the PCB for this..
  25. P

    10S custom skate ESC: testers wanted!

    Thanks. I tried the current .apk, but it fails to start properly (a message indicates "BLDCApp stopped" after a couple of seconds). The previous version (ui only) did work on the same device (Wiko kite) - I tried several thing with and without activating bluetooth initially.
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