Jump to content

WI_Hedgehog

Full Members
  • Content Count

    433
  • Joined

  • Last visited

  • Days Won

    1

Everything posted by WI_Hedgehog

  1. You may wish to read this series of posts on balancing, which appears to relate to your situation.
  2. HOW EUC FIRES ARE GOING TO BECOME MORE COMMON SUMMARY: To minimize the risk, use the Charging Best Practices. A new BMS thread popped up that relates to what we've been talking about with balance charging. The BMS got cooked. This post builds on how cells get out of balance, and state what happens next. This problem is compounded by using any/all of: recycled cells, charging to 80%, and fast-charging. To quickly recap, one of the dangers in using recycled cells is some cells will be near their End Of Life and start to go out of balance quickly, which is unexpect
  3. I think it's possibly more like top-tier sellers forcing battery exchanges, and I should have stated that more clearly. Gotway is probably not going to do more than they absolutely have to. If that is the case, it's potentially very short-sighted, and could cause a similar ban to the cheap-China-hoverboard ban where poor lithium battery management caused a fire in a plane's cargo hold leading to a complete ban on low-quality imports for a while. (I know someone who lost $150,000 because the ship was prohibited from unloading the hoverboard cargo. Of course, the Chinese were already paid,
  4. Well, there's the other shoe. I'm going to guess the reputable sellers got the Panasonic 21700 information from Gotway. Gotway possibly bought refurbished cells, and is now recalling them because, quite frankly, using used cells not designed for this task is generally a bad idea. China does a lot of "recycling," that's how all those plastic straws ended up in the ocean. Now we have the evidence they imported TESLA batteries in bulk and are ripping them apart for the cells. I can understand third party sellers using them, figuring "they seem good and are cheap, they'll last six months."
  5. So I learned something new, thank you @houseofjob !! Those sellers do indeed say Panasonic 21700 to this day! As far as I could find, Panasonic makes only one 21700 packaged cell, exclusively for TESLA. @Mike Sacristan seems to have gotten to the bottom of where the used cells are coming from. While there aren't any laser markings (my mistake), there are the three unique squiggles on the bottom of the cell as Mike mentions, though there is also the ultrasonic weld joint from the fuseable wire on the top: The seller adds various colored wrappers.
  6. I think you read my post incorrectly, as my position is since TESLA automotive cells are not available to anyone but TESLA, they are only used in-house, and TESLA doesn't have enough cells for their own use, the cells in Gotway wheels most likely aren't new TESLA cells. If TESLA/Panasonic was selling TESLA cells to third-parties, it would be big news. If for no other reason than real TESLA cells are very traceable, Gotway probably wouldn't buy stolen ("siphoned") cells to put in new EUCs. If Gotway was using TESLA cells, there should be evidence of it by now. Without any evidence at all,
  7. @someguy152, congratulations on being inventive, it's quite an awesome feeling, isn't it? I'm guessing you have three sets of 8S balancing leads to connect to 20S, and are checking voltage when at home with an 8S cell monitor. 24AWG Silicone Wire resists fire and melting reasonably well. Building Battery Packs (in case you're interested) Shrink wrap keeps the mechanical connections from vibrating & breaking, so it is important on packs, not as much on a BMS. Reasonable quality Kapton tape doesn't out-gas or cause chemical reactions
  8. He has fairly non-typical riding positions. For stairs he leans back, keeps his shins straight, and tilts his feet forward/down. (I'd fall off.) Also of note, that's a non-suspension EUC in @mrelwood's video, though a suspension should help make stairs easier.
  9. I [by mistake] live in a totalitarian community (in the U.S.) where everything the city government dislikes is considered illegal, and most other things they want you to purchase a permit (permission) for. This has prompted me to plan moving elsewhere in the future. Otherwise it is a very beautiful area. Despite this (and a flat-out ban on Personal Electric Vehicles) I ride hoverboards everywhere (and once I'm better will ride EUCs in public)--this is not without planning and consideration. Being very respectful goes a long, long way. Smiling, waving, and always letting other pedestrians
  10. (not directed at any one person) It is unethical to keep spreading the Tesla car battery rumor without evidence. Tesla prompted the development of larger 21700 cell for its vehicles, other cell manufacturers saw it as a good idea and copied the cell dimensions (the chemistry is specific to Tesla and otherwise unavailable). Some Chinese manufacturers make very low quality cells that are put in wrappers to look like name brand cells--this is not exclusive to 21700 cells, some companies copy everything from workout DVDs to clothing (the fashion industry has been plagued by knockoffs for
  11. @ShanesPlanet He's pretty crash-proof.
  12. EUC World app and a Bluetooth earbud. Doesn't annoy the world and lets you know what's going on at all times. (one earbud, so you can also hear the world around you)
  13. In that last picture it looks like a sea mine. Or terminator robot... 18650's have 10% more capacity per unit-volume than 21700 cells, so they take up less space for the same amount of total power output. Also, the amp output is higher when putting more cells in parallel.* *EDIT: Someone on this forum did the math with the latest cells, though I can't find the post. Looking around it seems it depends on the cells, 18650 vs 21700 varies...depending... So @mike_bike_kite might be right (see the next post).
  14. I believe the concern is uneven braking. Yes. During heavy braking with the Extreme firmware the acceleration/deceleration is stronger than factory. In my experience, stopping very quickly is rarely done in a perfectly straight, balanced manner. Example: You are going "fast" (3x the speed of walking=10MPH=16kph), looking around and enjoying the ride. Also watching your path, you spot a hazard which is now close in front of you, mostly on the right. Lean back and heavily brake. At the same time, steer left to try to avoid the hazard. Most of your weight/down-f
  15. Free-spin speed is one thing, but the torque curve is another. Gotway goes fast, but the torque falls off and cannot necessarily support the rider if they over-lean or hit a bump (depending on many factors). I'd like to see a torque curve before pushing a wheel to its limits, rather than to discover torque limits by exceeding them. @RockyTop said many things, though to focus on this one: I would not want to fall off the back of a pickup truck at 60MPH=100kph. Even as a stunt person this is very dangerous, though with this you hopefully choose when to jump, and how to jump. You w
  16. A lot of excellent information has been provided in this thread, to add a bit more: Cell balancing isn't overly important because battery packs have uneven wear due to uneven heating. Cells on the inside of the pack cannot shed heat during discharge and charge, and heat ages cells. (Cells generate heat, and are surrounded by cells generating heat, with no real cooling ability. This is partially why Tesla car company flows coolant through the battery packs.) Passive balancing works well, but not with fast chargers unless the BMS is designed to handle fast charging (they are not). Wh
  17. @mrelwood, I think @Jason McNeil doesn't know. The forum has a wide knowledge base from engineers, extensive R/C designers*, multi-PEV owners, and members who are super smart and researched the internals of their wheels and shared their knowledge here. An EUC design company doesn't even have that broad expertise base. EUCs are new to the market and tended to be obsolete before having battery issues. (We learned "what didn't work" from the hoverboard fires.) Newly introduced "fast" wheels are only recently being used as commuter vehicles putting on lots of miles. Batteries used to be small
  18. Really glad to see you suffered only minimal damage! A few scrapes and bruises and being stiff for a few days is excellent for splatting at that speed! That says a lot about your gear choices and skills! Also glad your custom wheel took the crash without being smashed! It's unfortunate this happened, though the good thing is the damage is limited to minor cosmetics for you and the wheel. I ride in the city for transportation because it's faster than a car during high traffic hours. Yesterday I slowed way down due to fatigue and not feeling sure of my skills while tired, even stopping to r
  19. Inside Veteran EUC: I told you no use Tesla battery! Look! Wheel on fire! Smoke everywhere! We get bad name before make first sale! Gotway: Same problem, different day. King Song: This why our wheels so slow--more safe. InMotion: (hope they no steal our suspension idea)
  20. This is the first wheel I've been really excited about. I want a fast wheel that is well-built, especially because the faster you go, the better the build should be; going fast in/on a "parts bucket" is kind of like the pod races in Star Wars...which is not great if you're the one crashing. From the looks of it, the V11 answers that call. Plus, it has batteries in the hub! [edit: almost in the hub] It's very controllable due to a great design! I was looking at the Gotway torque curves this weekend (@Chriull's post) , and am not so impressed--not to say anything against Gotway for this rea
  21. Thank you. I'm not convinced this fire is a charging or battery specific issue either. Having followed lots of Gotway threads I would personally want to open a newly ordered wheel and check everything over first. Gotway's Quality Control department seems to be the Glue Gun Guy: "If I can't glue it, screw it--it's a warranty issue and we have none."
  22. Summary: Always Balance Charge EUC Batteries It is true, charging to 4.0/4.1V maximum doubles the cell life. Discharging to 3.30/3.35V minimum doubles the cell life. (exact voltage depends on the cell chemistry) The problem is we cannot currently measure cell voltage, only pack voltage. So we assume 4.0V = 80% capacity & 3.3V = 30% capacity for the pack applies to each cell, but it does not. As @Archee Jan Bloch correctly points out, when the battery, which is the whole pack of cells, reaches "low voltage," it is for all cells in series. We do not usually know what the volt
  23. My understanding from the members here is all* major EUC manufacturers use top-balancing circuits. This is smart, as it is cheaper, smaller, lighter, and allows the most power into the cells the fastest. *The exception may be Ninebot/Segway, though I don't know. Both miniPROs I have use active balancing circuits that are always running and monitor each cell, even when the batteries are removed from the units and just sitting around. Because of per-cell monitoring and reporting, it is easy to see how fast a cell can start going out of balance and by how much. The miniPRO charges to 4.00V
  24. Note of caution: Charging to 90% doesn't engage the balancing circuitry in the top-balancing boards I've seen. I understand Gotway uses top-balancing boards. In theory, this could allow a cell to get out of balance and drop below critical voltage. At such a depressed state a cell can undergo a chemical change and permanently die, or overheat during use. The death of one cell affects those in parallel with it, amplifying the problem and increasing the risk. --- Also of note is cell design. In highly simplified terms, the more lithium there is in the anode the more powerful the c
  25. Great question. @MRN76's modification does not use any more battery power than normal. Going slow allows the motor coils to stay charged longer, increasing efficiency. This means you can go farther if you go slow. Going fast means the coils have to charge quickly, are only briefly pulling on the wheel magnets, then have to change polarity quickly, again to only briefly pull on the magnet. So going fast on an unmodified miniPRO or EUC uses more power than going slow, meaning you cannot go as far as if you went slowly. MRN76's modified firmware does not change the above. If
×
×
  • Create New...