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esaj

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Everything posted by esaj

  1. 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).
  2. 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/
  3. 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
  4. 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).
  5. I guess they're pretty random. But you could try mailing them directly and ask. The owner seems like a nice guy.
  6. Yeah, the sale price is only for the 420Wh version. Check out other possible options here:
  7. 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.
  8. 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.
  9. @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.
  10. 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
  11. I just bought a < 10€ guitar stand from Thomann years ago. Old picture, beautifully covered KS16S in the front
  12. 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.
  13. Rigol makes some relatively cheap oscilloscopes (300-400€ for 2/4 -channel 50MHz bandwidth, hardware unlockable to 100MHz + double memory etc): https://www.batronix.com/shop/oscilloscopes/DSO.html Right now they have a deal where you get all the options at the same price, except the bandwidth? I have the DS1054Z, haven't unlocked all the options (basically they should be bought separately, but there's a key generator online... ), but it's already out of warranty (3 years), so maybe one day if I need more bandwidth or such. To my knowledge, all the 4-channel DS1000's (1054, 1074, 1104) are actually the same hardware, except for the logic analyzer in the Plus-models, otherwise the difference is just the (software limited, unlockable) options. They're not super high quality precision instruments (such cost high 4-figures or 5-figures anyway ), but easily good enough for occasional hobbyist usage and they've got a lot of features for the price. The only downsides I've hit is that the internal voltage noise is relatively high if wanting to measure really low ripples (can't seem to measure reliably below about 0.8mV, which seems to be a lot for an oscilloscope) and the FFT is slow and not very precise, so a separate spectrum analyzer would be needed for such measurements.
  14. Where is the data captured from if you don't have a Charge Doctor, from the wheel telemetry? That's a lot of noise... I've never looked very closely at the wheel voltage measurements, I'd guess that at least in most cases it's just a voltage divider feeding directly into an ADC-pin of the MCU, and if done "poorly" (no filtering, lots of SMPS noise in the system), there can be a lot of noise in the signal. They (likely) just divide the voltage, so the battery voltage range is "mapped" from 0-67.2V to 0...less than 3.3V (to leave headroom in case of overvoltage, so it won't blow the ADC), say 0...3.0V. 12bit ADC can give 4096 different values, but if roughly 10% of the top end is left for handling possible overvoltage and spikes, that leaves around 3600 values for the entire range. 67.2V / 3600 = about 19mV per LSB, which isn't that bad really, should be easily enough resolution for battery voltage measurement. The noise amplitude seems to go up to around +-0.5V from the average, so a total of about 1000mV or about +-50 on the ADC-reading, so likely it's not just "normal" noise of a few LSBs that tends to end up in the measurements unless special care is taken in layout, shutting down peripherals etc. Maybe there's no filtering at the divider at all? If you have an oscilloscope and some courage, you could try to measure the ADC-pin noise when it's not charging and during charging. One possible source might be the charger itself, I don't think that the cheap chargers have much in terms of filtering the output noise, so that might be another place to take a peek at (with an oscilloscope).
  15. There's still ambiguity about the terms, but what I think of as "cut-out/cut-off" was the early wheels that would actually seem to cut power to the motor based on reaching certain speed, regardless of battery state, which is just crazy, or the BMS overcurrent protection killing all power under heavier load. At least to my knowledge, no (brand) wheel produced these days or within the last 2-3 years does those.
  16. Found this, standard sizes here: https://www.woodproducts.fi/content/standard-sizes-thicknesses-widths-and-lengths
  17. Two-by-four is a commonly known term here, but nowadays at least hardware stores seem to indicate the dimensions in millimeters, for example 45x95 or 48x98 are more or less standard sizes, both are close to 2x4", the slimmer one's planed. 48x98mm comes down to about 1.89" x 3.86". Also "even" numbers are common, like 50x100mm, which is actually even closer to 2x4 (1.97 x 3.94"). My guess is that the sizes are based on "traditional" imperial sizes as they seem come very near the whole inch-values.
  18. Muistelisin jonkun ( @EUC Extreme ?) laittaneen kuvia/videota joissa käytettiin hydrauliprässiä akselin vaihtoon joskus aikoja sitten, eli ei ihan helppo homma. Tai ehkä on, jos löytyy sellainen nurkista
  19. @hobby16 has a list of connectors and their polarities in his site ( http://hobby16.neowp.fr/2016/11/20/charger-customization/ ), I guess it's ok to copy-paste them here. Do note that these are from several years ago, and newer wheels might have different pin-out or connectors, so check beforehand to be sure: Most frequently found connectors e-Wheel Socket Wiring Voltage Topo* Remark Most e-wheels GX16-3 1: V+ ; 3: 0V 67.2V 16S connector for Solowheel, Airwheel, Gotway, Firewheel, King Song… Gotway MSuper3 84V/1600Wh GX16-4 1: V+ ; 2: 0V 84V 20S other MSuper3 with battery <1600Wh have GX16-3 connectors IPS (Holtz, Zero…) GX16-4 2: V+ ; 4: 0V 67.2V 16S warning, same connector as above but different wiring! InMotion V8 ** GX12-3 1: V+ ; 2: 0V 84V 20S same connector & wiring as hoverboards InMotion V3,V5 Lenovo Int:V+ ; Ext: 0V 84V 20S Lenovo square socket, originally for Lenovo laptop power supply Ninebot One*** Lemo 63V 15S see photo for wiring*** Ninebot Minipro, Xiaomi ** GX12-4 1: V+ ; 4: 0V 63V 15
  20. I missed all the "fun" of this shit storm... Big thanks to other more active moderators for keeping things running, I guess I'm more or less retired now, haven't been that active for the last... year?
  21. If it's indeed the same device, then it's a good deal. But the datasheet for MP157 does say that: "Avoid the minimum DC voltage below 70V. Low DC input voltage will bring the problem of thermal shutdown." So I don't think they're actually the same device. MP9488 could probably be used without issue in place of MP157 with rectified AC (it can handle the high input voltages), but likely not the other way around, when the input is lower DC voltage. But, of course if it works without issue down to minimum voltages needed in charging, then why not. Can you try to run it for several hours straight at low voltage and see whether it overheats / goes to thermal shutdown? Say, 50V DC?
  22. Nice, I looked at some of the MPS-regulators earlier, but all the suitable models were out of stock and no information when they might become available again (but that was 3-4 months ago ). That's a huge price reduction vs. the Linear Tech-devices. EDIT: Oh wait, that's an AC/DC -regulator, the datasheet suggest rectified 85-265V AC input, what's the lowest DC voltage it still works with? The device would need to work on a 16S or 15S with depleted batteries, so the charger output might be <50V, thus why I was looking for input ranges from about 40...45V (empty 15/16S) or less up to 105V or more (full 24S). I've never seen anything other than 85V AC mentioned as the lowest input on the AC/DC-models, and never tried anything but DC/DC-switchers, if the AC/DC's can work down to 45V DC or so, then there's a lot of options. Although if the minimum RMS AC voltage is 85V, it would mean min. 120V DC, but apparently you're already using it on lower voltages. A quick glance on Electronics Stack Exchange advises against using less than the minimum voltage though, apparently the device can overheat due to undervoltage lockout -problems even if it seems to work fine for a while. This was the MPS-model I was looking at earlier, out of stock and lead-time of 19 weeks: https://www.mouser.fi/ProductDetail/Monolithic-Power-Systems-MPS/MP9488GS-P Works from 7.5V up to 450V DC input.
  23. There are PCB-mounted XT60's/90's available, for example: https://www.tme.eu/fi/en/katalog/dc-power-connectors_112990/?visible_params=2%2C6%2C613%2C422%2C7%2C9%2C1247%2C1322%2C18%2C2555%2C5%2C416%2C77%2C11%2C412%2C2671%2C413%2C419%2C2546%2C424%2C177%2C1427%2C1428%2C68%2C13%2C2467%2C32%2C205%2C1424%2C516%2C646%2C426%2C909%2C82%2C511%2C21%2C1182%2C1335%2C536%2C328%2C329%2C138%2C1323%2C247%2C527%2C49%2C69%2C35%2C1382%2C117%2C10%2C20%2C635%2C1605%2C418&mapped_params=2%3A1260%3B416%3A1641369%2C1641370%2C1641371%3B1322%3A1436472%3B (Filtered by AMASS, XT30+60+90+150, mechanical mounting on PCB) I haven't really worked on this apart from doing basic calculations for the step-down circuitry. Maybe one day, but lately I've been too busy to even think much about this... If the monitor is separately powered, it's relatively simple and cheap to make, but "proper" step-down for the entire voltage range (still about 40-45V to about 105V to account for all 15-24S battery systems at full and empty voltages) seems to add too much to the cost, unless someone has found a good & cheap SMPS-controller? Of course, if limiting to max. 84V systems (20S batteries), there a lot more options.
  24. I had a metal cap with the Firewheel, no issues there, looks like it's similar (rubber inside the cap to prevent short circuits).
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