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esaj last won the day on May 11

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  1. Check that your multimeter probes are connected correctly (current vs. voltage measurement) before measuring. The power spike before the BMS cuts the power / meter fuse blows is enough to vaporize your probes if you plug them in the battery connector with the meter set up for current measuring... guess how I know? Acetone can be used to "weld" plastic, it liquifies the plastic, which then hardens again once the acetone evaporates. Use small amounts at a time and be careful, the plastic starts to melt pretty quickly. Also inhaling the fumes a lot isn't exactly healthy, so good ventilation isn't a bad idea. Never had more than a slight headache though Mixing plastic (such as Lego-blocks, which are ABS, or something like 3d-printer filaments probably would work nicely too) with acetone creates a "slurry" which can be used to fill in small holes or cracks, or create new threads for screws in plastic (fill the hole to re-thread with the slurry, insert the screw, maybe move it a little bit up and down to ensure the liquid plastic settles in the threads and leave it there until the acetone has evaporated and the plastic has hardened). Easiest way to make small amounts is to take a small glass jar (preferably with a lid), pour some acetone in there and drop the blocks or 3d-printer filament or whatever there, close the lid and swish it around for some time until it has even consistency (the time it takes depends on plastic, sizes of blocks, amount and purity of acetone... if you just leave it sitting it will take a long time, but twirling it around makes it much faster). More acetone vs. plastic makes it more runny and vice versa. Somebody with more understanding of chemistry once said that using solvent-based "gluing" is far superior to "normal" glues, because the bonds occur at molecular levels, ie. basically the parts melt together instead of being held together by a layer of other substance. Draining the caps is a good idea before touching anything on the mainboard, probably pressing the power button is enough, or just place a small resistor across the cap legs and wait a bit (careful not to short anything else with the resistor legs!). But when plugging back in, the discharged caps will pull a high current spike when they recharge and can cause sparking, people have destroyed the connectors this way and in at least one case, the MCU fried (Rehab1's ACM). Either use a XT-90 with "spark arrestor" or use small resistors (if you don't know what I mean or how, then don't try it, I don't have the time to draw a diagram right now ) between the battery and mainboard connectors first to recharge the caps, then connect normally.
  2. The ubiquitous term used most commonly has been "wheel" ("wheels" for plural) for years now.
  3. I don't actually check the voltages themselves, but over the last winters, I've stored the wheels discharged to something like 30-40% for 6-7 months at a time, and they've never discharged enough to even drop much, ie. looking at the LEDs showing the charge, I've had 3-4 LEDs on out of 9 on both KS16's when putting them to storage and still had 3 LEDs on in the spring. All batteries were left connected to the wheels, since KS's don't draw power from them when off (most wheels don't, with the exception of Ninebot Z-series which have relatively huge vampire drain that sucks full batteries to empty in about a month or so, those things need to be charged often during storage, or preferably, disconnected from the wheel mainboard!). For other than Ninebot Z's, likely the only thing using power when the wheel is off is the BMS, and the current it draws seems to be somewhere in the microampere-range, and then it won't matter if the packs are connected to the wheel or not. Four 16S1P -packs each with their own BMSs I've stored in a ground basement under the house, that has temperatures ranging from freezing to maybe 15-20C, have been there for about 2-3 years without charging in-between, when I checked this spring, they were around 56V (I think I charged them to around 57-57.5V when I put them there).
  4. The ACS712 is a current sensor microchip using the hall-effect (magnetic field caused by flowing current) to measure the amount of current and output it as an analog voltage signal. https://www.allegromicro.com/~/media/Files/Datasheets/ACS712-Datasheet.ashx My best guess would be that the controller might go into some sort of overvoltage lockout if the motor isn't turning and it senses too high voltage (48V controller sounds like it's meant for something like 11S or 13S batteries). Have you tried discharging the batteries to a lower voltage to see if it then starts running? Then again, if it starts running without load (if you mean you turned the bike upside down by "backwards"), it might be related to the ACS712 (controller detects overcurrent when the motor's still stalled at start-up), in which case maybe a small voltage divider to drop the detected current value might work? EDIT: No, it won't work, the sensor's bidirectional, so it would move the offset away from the "zero current" -point at half the supply voltage, it would need a more complex set up with an op-amp or such... But I'm really just guessing... Either way, perhaps it would be best to get a controller that has suitable maximum voltage for the batteries? A better place to ask might be something like the Endless Sphere (e-bike) forums: https://endless-sphere.com/forums/
  5. Yeah, time has flown pretty fast looking back. I removed the foam after the first summer, no video though Not that there'd be much to see, I purposefully used a crappy 2-sided tape (not the 3M-stuff) that was easy to peel off and left without leaving marks. If it would have left residue, I'd have just cleaned it off with IPA anyway... But here it is in its original beauty: <3
  6. Yeah, the funny thing is that the price has stayed pretty much the same since the release. Guess there's enough demand for them still that there's no need to drop the price. I've been happy with mine, zero issues after 3 summers and while I haven't measured the actual battery capacity since the first summer, I haven't noticed a drop in the capacity so far (although likely after that long there is some).
  7. I guess they're pretty random. But you could try mailing them directly and ask. The owner seems like a nice guy.
  8. Yeah, the sale price is only for the 420Wh version. Check out other possible options here:
  9. 1RadWerkstatt: https://www.1radwerkstatt.de/epages/80603321.sf/en_GB/?ObjectPath=/Shops/80603321/Products/KS16[1] Currently 1029€ for the 420Wh version, 1449€ for 840Wh. Free shipping within EU-area. Bought my KS16S (White, 840Wh) from there in the spring of 2017.
  10. Pari kertaa varmaan sen ajolasi-tyypin nähnyt, yliopiston liepeillä ja uudelleen Tourulan suuntaan menossa, musta pyörä leveällä renkaalla, näytti Ninebot Z:lta. Omat ajelut loppui tältä vuodelta tällä viikolla kun tiet oli jäässä aamuisin jo heti alkuviikosta, ja näyttäisi että lämpö pysyttelee nollan alapuolella tästä eteenpäin.
  11. @EUC Extreme käytti ruuvattavia nastoja, ilmeisesti pito on erittäinkin riittävä "normaalissa" ajossa, tosin nastat taisi olla verrattain kalliita (luokkaa ~100€ / rengas?). EDIT: Muistelisin että ulkokumeissa on käytetty jotain vahvikkeita (kevlaria?) sisäpuolelle liimattuna ettei nastat puhkaise sisäkumia, joten jonkun verran värkkäämistä noissa on.
  12. RECOM also does board-mountable switching-modules with isolation and whatnot, but the issue is the price. If the end user should be able to build / buy the parts for about 25-30€ total or less, the module alone would pretty much eat the entire budget
  13. I just bought a < 10€ guitar stand from Thomann years ago. Old picture, beautifully covered KS16S in the front
  14. I'm fairly certain that the above is wrong, but if I'm wrong, somebody please do correct me, always happy to learn. In King Songs, the BMS does not "output" voltage towards the charger, there's a reverse polarity protection in the charging side which as a side-effect also prevents reading the battery voltage from the charge port with a multimeter (you might see a few volts as the mosfets leak a tiny bit of current "backwards", but not the actual voltage). On the other hand at least some older Gotways, if not also all the new ones, don't have reverse polarity protection, and you can read the voltage from the charge port. However, the charger does not "use" this voltage reading whether it's there or not, instead, the charger drops its own output voltage if the current limit (like 5A) is hit until the current stays at that limit. It cannot "directly" control the output current, but the control is done through altering the output voltage. This is the CC (Constant Current) -charging phase. Once current stays within this limit when hitting the maximum output voltage, the CV (Constant Voltage) -phase begins, where it just keeps the output voltage at the maximum (like 84V), and the current dies out slowly as the battery charges and the battery voltage goes up towards the charger voltage (the difference between the charger output voltage and battery voltage drops, since the resistance between the two is more or less constant, the current drops: I = U/R). I'd speculate (like others have before) that in this case the faulty charger output voltage has raised high enough to destroy the BMS charging-side protection mosfets. Never seen the KS BMS, but I'd guess they're using something like 100V max mosfets there, and a high enough voltage spike from the charger has fried the protection, allowing the cells to overcharge. They might have gotten severe damage at this point, but not enough to cause a fire. Once the badly damaged cells were charged using the normal charger, an internal short circuit inside a cell or such caused the temperature to raise beyond the critical "thermal runaway" -point (something like 125...150 Celsius), at which point the cell catches fire that keeps feeding itself. But that's all just guesswork.
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