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  1. K

    Inductance question when connecting 2 batteries in parallel using ideal diodes

    Any possibility wire length inductance (or voltage ripples) increases when using diodes or is it unrelated? It seems to me the current flowing through the whole battery wire would be "trapped" in a smaller portion, between the controller and the diode, when the motor shuts off...
  2. K

    Inductance question when connecting 2 batteries in parallel using ideal diodes

    I don't have the skills to read such complex diagram unfortunately. However, it seems wire inductance can still cause issue. Here is what I came across: "Adding wire length (inductance) in battery to controller wiring is very bad for the controller. It causes increased ripple in the capacitor...
  3. K

    Inductance question when connecting 2 batteries in parallel using ideal diodes

    The bike has no regen and it's not a direct drive. It's a mid drive motor with a torque sensor. This is probably why the BMS does not allow charging through the discharge leads. So without regen and no direct drive, does it mean it's a safe setup? Is a zener clamp still required? Where would...
  4. K

    Inductance question when connecting 2 batteries in parallel using ideal diodes

    No the fat wires are not coiled. Actually they are standard wires (same gauge as the other wires, AWG14) and are just fat for the purpose of illustration (section between controller and diodes). However the motor is coiled and I don't know how back EMF when the motor is turned off is passed...
  5. K

    Inductance question when connecting 2 batteries in parallel using ideal diodes

    Hi, I'm interesting in connecting 2 36V Li-ion ebike batteries in parallel using ideal diodes (e.g. mosfets) for reverse current protection. I know that (in principle) ideal diodes are not needed if the two batteries are connected with the same state of charge. However I have to use diodes in...
  6. K

    Using RC charger to measure wire resistance

    Thanks for your input! The power supply is going to be a car battery but I don't know if it this will provide "clean" DC as the battery is going to be basically shorted (using a heavy duty contactor solenoid) to make the spotwelds. The current spike should only last about 20 milliseconds or so...
  7. K

    Using RC charger to measure wire resistance

    The purpose of measuring the resistance of the AWG5 cable is to then use that cable as a shunt resistor to measure very large DC currents (e.g 500-1000A over few milliseconds) in a DIY battery spotwelder. The sense wires that will probe the voltage drop across the AWG5 cable will likely have to...
  8. K

    Using RC charger to measure wire resistance

    Yes my Icharger 3010B also has a hot wire foam cutter option and actually I thought about using it initially. The charger's documentation mentions that you need to set both voltage and max amperage for this mode and I (stupidly) thought I'd need the actual current to be fixed rather than the max...
  9. K

    Using RC charger to measure wire resistance

    Hi, I'd like to measure the resistance of a AWG5 wire over a distance of 50cm. I know that I may calculate a theoretical value by considering the ohm per km for such cable (about 1.1 Ohm/km) but I'd like something a bit more precise by sending a constant DC current through the wire a measure...
  10. K

    DIY spotwelder with car battery + solenoid: some questions

    Hi, I'm only interested in welding 0.2mm thick pure nickel (possibly slotted) ribbons onto 18650 or 21700 cells. No copper/nickel sandwich method needed in my application.
  11. K

    DIY spotwelder with car battery + solenoid: some questions

    Hi, I'm interested in building a cheap DIY spotwelder using a 12V lead-acid car battery, a heavy duty contactor (Tyco EV200 rated at 500A continuous, max 650A make current to avoid contact welding but break current could be up to 2000A) and controlling the timing with an Arduino board. My...
  12. K

    40T, neodymium magnets, plasti dip cycle test

    Great, thanks! I didn't know you were using 1mm thick magnets. Thought it would require at least 3mm to provide sufficient pull. But that's great to know that 1mm is enough (hope it's still good with your 0.1mm thick copper plate). Do you also use 1mm thick magnets for 21700 cells? Regarding...
  13. K

    40T, neodymium magnets, plasti dip cycle test

    Really interested by your approach to a solderless pack! I'd just have some questions on things I may have missed in the thread: - You're using 7.5mm diameter magnets on 21700 cells, right? Could you precise what's the thickness of the magnets? Why not 10mm diameter magnets on 21700 cells? -...
  14. K

    40T, neodymium magnets, plasti dip cycle test

    @goatman Great tests! Did you test the temperatures with the PlastiDip or without it? Also, what do you think about covering the vent holes on the positive terminal with PlastiDip? Is this not something to worry about?
  15. K

    10S4P with Samsung 29E vs 10S5P with Samsung 26H

    See here: https://www.e-bike-vision.de/product/powerpack-for-bosch-classic/en In fact the 468Wh pack has Samsung 26J cells (not 26H) but AFAIK the characteristics are the same (e.g. max 5.2A discharge as well)
  16. K

    10S4P with Samsung 29E vs 10S5P with Samsung 26H

    Thanks! Then I think I'll stick with the original Bosch 400Wh since I've been extremely happy with the cycle life of my pack (8 years and about 30'000km). Another advantage is that being a 4P, it is slighlty lighter than a 5P. Having more range would be great but I doubt that going from 400 to...
  17. K

    10S4P with Samsung 29E vs 10S5P with Samsung 26H

    Hi, I'm about to buy a new battery pack for my Bosch ebike. My ebike is 36V with a 350W nominal motor. However afaik the motor can draw up to 540W peak. Not sure whether this is exact but I guess that max amperage should always be <18A anyway. I'm considering two different packs: - 10S4P made...
  18. K

    Bosch mid drive with vesc controller

    @mechhead If I understand it correctly, you use a VESC 4.12 in sensorless mode with the Bosch motor. I would be interested to know if you use sensorless BLDC mode or sensorless FOC mode and whether you experience cogging when the motor starts to assist at low RPM? I'd be interested to do the...
  19. K

    BMS or Hobby Charger

    I'm also considering using a hobby charger (iCharger 3010B) instead of a BMS for a Li-ion (10S6P samsung 29E cells) ebike battery pack (no Lipo for me). I understand that with a BMS, not having to plug the balance plug everytime would be simpler. However why would it be safer? Do you mean there...
  20. K

    18650 spot welding -how to- ULTIMATE REPOSITORY

    Interesting! Would you have a link to the kind of solar panel bus tape that you used? Thanks!
  21. K

    18650pack cell protection idea. PTC + fuse & diode).

    In my case, the battery would be used without BMS and would be charged with a balance RC charger. Since the balance wires must be connected/disconnected on every charge, withthe balance plug sitting outside the pack, I'd have seen some potential benefits if fuses placed on the balance leads (the...
  22. K

    18650pack cell protection idea. PTC + fuse & diode).

    Sorry I don't get it. A regular fuse (i.e. non PTC) is a passive element so he cannot go that route either then. Do you mean he should only use a regular fuse after the BMS (as probably everybody does) and not protect the individual balance leads? I'm also interested in the idea of fusing each...
  23. K

    BOSS LEVEL CUSTOM SPOT WELDER

    Really sorry to read that, Rojitor. Take care!
  24. K

    BOSS LEVEL CUSTOM SPOT WELDER

    Great design! I'd be really interested to see a video of that build. By the way, could you explain why you did spot-welding + using magnets? Would the magnets not have been sufficient to provide a reliable and secure connection? Also, could you share how you did attach the main battery leads to...
  25. K

    DIY Li-ion battery: first connect cells in series, then in parallel

    That's what I wanted to read :) Indeed the pack will always remain in the 10S6P format with parallel connections being made at the cell level. So series first or parallel first doesn't matter.
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