Search results

  1. R

    Ninja 250 "Clone" Made in China

    Just an awesome story, starting with a guy skimping on battery and unfolding into an engineering feat. You're dangerous, sir!
  2. R

    L.A. approve Measure HLA to make room on streets for bikes, buses

    It's going to be a difficult project even if right decisions have been made now. You can't rely on politicians sticking to decisions of their predecessors especially if reversing the whole thing would get them some popularity. But i agree, mixing buses with bicycles on same lanes is just insane...
  3. R

    Help with first pack build

    I can give some advice, but the value of it may be random, i'm not a very advanced builder - if you can't / dont want testing, charge the cells and give them few weeks of rest, then measure voltages, find outliers with voltage dropping more than 0.1V (i dont know what is the right value here...
  4. R

    BifRC PCB spot welder - gate driver modification help & advice needed.

    I dont know, my colleague is using something similar and is quite happy with that (but not this exact type), but anyway this is an example, different shops make different types of devices - you'd need to ask about specific materials and capabilities (the one i linked, it says there that you...
  5. R

    BifRC PCB spot welder - gate driver modification help & advice needed.

    which country? look for small workshops with hand-made welders, example,zgrzewarka-punktowa-z-elektrodami-auto-wyzwalanie
  6. R

    Cordless conversion for Black & Decker MM850 Mower

    This is a nice idea/hack to run a brushed AC motor on DC, worth knowing. But not very practical for battery build, especially 230V version Regarding the trimmer, some time ago i bought a no-name 36V cordless trimmer with a brushed motor, for like 25$ new (no battery). Cheap, simple construction...
  7. R

    Still big scooting in San Jose.

    I think for DIY builders here we should make an assumption that they know what they're doing and did their thinking and testing already. No need for patronizing remarks, this will not save anyone...
  8. R

    Still big scooting in San Jose.

    well, regarding bike frames, if you build from carbon fiber you expect it to be superlight too, so you only use as much material as is necessary. I think that's the main reason carbon frames break, same with thinned aluminium frames. Make them just a bit thicker, give some more margin, and they...
  9. R

    Ring gear / drone motor Ebike prototype

    Very nice idea. But what's the purpose of the small ring gear, it appears to do nothing to the gear ratio. If it's for freewheeling, how does this work?
  10. R

    Still big scooting in San Jose.

    well, all carbon bike frames are basically fabric and glue and they're pretty tough
  11. R

    Freenove ESP32-S3-WROOM CAM Board on my bike

    doesnt a mirror have better resolution? (but this could be useful for continuous recording)
  12. R

    The Barncat Battery- No weld/no solder

    Very nice idea and execution. Ability to disassemble a battery easily is a big advantage,especially for DIY builds. Recently i thought about somehow mixed idea - build a modular battery from just parallel sections. These could be reliably made solderless, just on mechanical contacts, and pretty...
  13. R

    Was bound to happen?

    When you're riding a bike in Poland, beware of hunters. They're notorious for mistaking cyclists with boars, at least that's the common line of defense. If it walks like a boar and quacks like a boar, and has two wheels - it must be a boar. Might also have something to do with alcohol so common...
  14. R

    Electrifying my track bike

    Looks like you don't need electric bike to be fast, you just need to ignore all the traffic rules
  15. R

    Motor recommendations for 16% climbs?

    One with a high-rpm BLDC motor and belt/chain transmission, sounds great (sorry just noticed -no subtitles and videos are in Polish) another one (built by professionals), for serious mountains
  16. R

    Why is my polaris battery doing this when i plug charger in.

    I think, someone with a bit of experience, could take this battery apart and measure the voltage of every section. Probably after 8 years most of the cells have self-discharged. By charging each section separately there's a chance to bring it back to life, or determine if the cells are dead for...
  17. R

    Lithium battery fire risk and information.

    I havent heard any success story from Tesla (or any other car manufacturer) about battery fire contained by the enclosure. The only reports available on the Internet show car completely burned.
  18. R

    What makes these cheap Chinese chargers so dangerous?

    If you have a charger with voltage monitoring then it's allright, i thought about simple case when you charge the battery with just a dumb charger, and rely on internal battery circuitry to protect it. Then, when something breaks and some cells overcharge, you wouldn't be aware of that.
  19. R

    Lithium battery fire risk and information.

    I dont know if a metal ammo box will prevent the fire from spreading out and igniting everything around, but it pretty much guarantees that everything inside will burn faster and completely. Even if a fire is relatively small, the temperature rises much faster when everything is confined in a...
  20. R

    What makes these cheap Chinese chargers so dangerous?

    You can't exclude overcharging - if we can assume a charger can break and develop a short circuit, then also some bad things can happen to BMS, protection circuit etc. But i wouldn't be that worried about short circuit in the charger - there are pretty thin wires and pretty flimsy connectors...
  21. R

    What makes these cheap Chinese chargers so dangerous?

    The typical cause of battery fire is a short circuit, which shouldn't happen during charging. But there are some videos (one at least) suggesting that a seriously overcharged cell may ignite. But this video shows that they really abused this cell, it was charged to 4.7V at 5.15 amps. Maybe same...
  22. R

    48v 10ah battery issue

    So it shouldn't be possible to charge the battery above 54.6v. And you claim that battery is at 56.9 One of these measurements is wrong Apart from that, I don't think any BMS would disconnect the battery on slight overcharge - that would be stupid to not allow it to discharge. With small...
  23. R

    Building not an eBike.

    I think a geared hub motor would be able to provide the needed speed and torque (but would have to be modified to be engaged in both directions, not freewheeling). But controlling that would be a fun project (however, there are many awesome open source projects dealing with various control...
  24. R


    just use a volt meter to check the charger voltage, but it should be at 42v and if charging is stopped earlier it might be because BMS has disconnected it. It stops charging when some sections reach 4.2V limit (but then some other sections are lower than that - thats why total voltage is below...