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esaj

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esaj last won the day on June 1 2018

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About esaj

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  1. esaj

    Open-source EUC motherboard

    Someone posted a link to this project in another topic about control boards maybe about a week ago: https://github.com/blezalex/WheelBoardMain Maybe that could be used as a base, it's for STM32F103 (Cortex-M3) and contains the library for using the MPU6050 -IMU, although there are probably other similar projects floating around. I might have a try myself at some point, currently I'm crash-coursing myself through ARM Cortex-M's datasheets and literature (and specifically Cortex-M3/STM32F103, because it's the only chip I have at hand at the moment), as I'm supposed to start a new job as an embedded developer next month, but haven't used anything other than Atmel AVR for hobby stuff and in school over a decade ago
  2. esaj

    Storing the fast charger

    Don't know about storage, but that looks like cord that goes to a mains outlet, right? Replacing it shouldn't be much of a hurdle though (Make sure the cord's unplugged and the input capacitors inside are discharged, otherwise there may be high voltages still present!): Open the unit Use a multimeter to check that there are no high voltages present (the capacitors, big metal cylinders inside the device, can hold a charge for quite a while even if the device has been unused and unplugged) If there are high voltages there, discharging the capacitors through a resistor is a safe way to discharge them, don't poke both of your hands in there though, you don't want a shock going from hand to hand, crossing through your chest and heart Locate where the wires from the mains cord go inside Likely there's two wires screwed or soldered to the circuit board somewhere If the casing's metallic, there should be a third wire that's connected directly to the casing, this is the protective earth (also called "ground" by many) in Europe it should be striped yellow-green in color, but don't know about US, make sure to connect the same color back to the casing when connecting the wires back If you're not sure you can remember where the wires go later on, take a picture just in case, so you can check it later Disconnect the wires (may require a soldering iron and/or screw driver) and pull out the cord Cut the cord from below the broken part Slide the cord back in through the strain relief Strip the outer layer of the cord and then the wires inside (there may be two or three, depending whether the units' earthed) Reconnect all the wires inside, make sure the (possible) protective earth wire is the correct one, check your picture if you don't remember which one goes where Close the unit You might also use another cord, if the original doesn't seem good, just make sure to use the same type of plug. I have a plastic bag full of old computer (ATX) power cords that I use as replacements when needed. At least here in Finland, it's legal to replace a damaged cord of 1-phase devices by a layman, if you're certain you know how to do it safely ( https://tukes.fi/en/home-and-leisure-time/restoration-and-renovation/do-it-yourself-electrical-work ). If you feel unsure of doing this yourself, ask around if you know anyone who can do it. I'd do it for you for free, but unfortunately I'm across the globe Also probably pretty much any electronics/electric/home appliance repair shop can do it for you for a modest fee, since the procedure is more or less exactly the same for pretty much any device (for 1-phase devices).
  3. Veikkaisin että valmiiksi rakennettuina akuista ja noista moottoreista saa maksaa yhteensä enempi erikseen tilatessa, joten rakenteluakin ajatellen tuo on jo hyvä hinta. Eipä tosin ole itsellä just nyt käyttöä, tuskin tulisi ajeltua ja akkuja olisi ennestäänkin enkä moottoreille heti keksi mitään käyttöä... Nurkat ylipäänsä täynnä rojua ennestään jo sen verran että pitäis varmaan kaatopaikalle kohta kipata
  4. The description mentions it has "cc" (constant current) mode on couple of occasions: DC 8-60v to 10-120v 900W numerical control cc cv step up module can display output Voltage, current, power and capacity and other parameters; has out, cc, cv indicators But, 900W rating to load at least sounds pretty high for that, considering the size of the heatsink etc., I tried to calculate conservative values for load modules I was designing some while back, and using larger heatsinks than here, the end result was that I should dissipate less than 25W per module... but the use case is different (purposefully dissipating power in the power transistors, where the mosfets are the limiting factor) and using free air -values, the module shown here does have a separate cooling fan and (at least supposedly) is designed to minimize the power loss in the switch. Soo... it's not really even comparable And I'm just a hobbyist, it might very well be that the module designer knows better (or not, I don't really know) Then again, a lot of places I read about electronics design do critique a lot of the (usually) Chinese cheap products available online, due to way too high promised specs and sometimes due to safety hazards, sometimes pretty serious ones. Still, if the step-up module here is (supposedly) capable of driving loads with hundreds of watts, it might very well be able to charge packs at <100W power (that means you charge <100Wh per hour of charging). As for actually going up to all the way to 900W, I doubt it. Compare the size of this thing to big name brand computer ATX-power supplies: In about that size, how many big name PSUs will you find by known high quality manufacturers (there will be a number of "unknown/no-name" Chinese brands that will claim >1000W though ) that promise 900W or more of power output? The big names have reputations to uphold and won't skimp on component quality, but you can expect to pay at least a couple hundred of euros/dollars for the high power PSUs.... Still, it's not (again!) really comparable, as those PSUs have to first drop the AC mains voltage (something like 220/240/110/120 volts RMS AC depending where you live) and regulate it to 12V/5V/3.3V (there's also a -12V rail but it's for low currents) within the ATX-spec ripples (10% I think?)... I'm not even sure what I'm rambling about, in conclusion that thing is probably capable of stepping up the voltage of a car battery from around 12V to 84V for charging, plus has at least workable/decent quality current limitations, but stepping up the voltage about 7 times higher from the input is going to already hit the efficiency pretty bad, not to mention the at least dubious 900W rating... yeah, probably you can get up to 100W if not more charging power to your packs from this thing, but it might draw 1.5 to 2-times (150W-200W, numbers I pulled out of my ass, worse if you draw more current) from your car battery at the same time, and if you're charging something like an 840Wh or larger battery pack from pretty much empty, it's going to take basically 8.5 hours or more to charge it fully. Not to mention what I said about the car battery capacity, so you need to run your car at times or your car battery will go empty....
  5. Hobby16 sells the Charge Doctor (various versions, afaik the only difference is the charging connectors, as different manufacturers/wheels use different connectors, and the beefier versions can use two chargers at the same time to charge faster): http://hobby16.neowp.fr/buy/ The device sits between your actual charger and the device you're charging, measuring the voltage and current, and using that information to calculate the amount of amphours/watthours that go into the batteries during charging: Above: Testing batteries of used KS16B 680Wh with dual chargers. The charging is pretty much finished (0.02A = 20mA going into the batteries), and the total watthours charged to the batteries is 672.3Wh. To get correct reading, you first need to discharge the battery to as empty as possible. No idea if the Ninebot / Ninebot Mixte -models are compatible with NineBot Elite+, as all of these were originally made for different EUCs. Still, I'd expect it to, as from manufacturing economy point it would make sense for them to use same batteries and chargers across different products, but better check at least that the connectors are correct beforehand. The price is around 27-29.50 in British pounds (shipping included). In addition to just measuring the amount of amphours/watthours going into the batteries during charging, it can also stop the charging at certain current to make it possible to charge the batteries to less than 100%, for example to charge the batteries to a lower charge state for storage or expand the battery lifetime if you don't need the 100% charge always. There's also datalogging for drawing charge plots with a computer & spreadsheets or other graphing software (but that's rarely useful, nice "gimmick" though ). Charge Doctor V2 features Voltage: 20.0V – 100.0 V Current : 0.00 – 10.00 A Charge : 0.000-1000 Ah with automatic decimation Energy : 0.0-10000 Wh with automatic decimation End-of-charge adjustable current threashold : 0.1-8.0 A Datalogging serial output 9600 bauds TTL In/out with 3-pin GX16 aviation connector (Airwheel & clones, TG, iezWay, Gotway, Firewheel, most e-bikeboard…) or Lemo connector for Ninebot Dimensions : 85x50x20 mm Weight : 65 g If someone with a Ninebot Charge Doctor lives nearby, you could of course ask to borrow theirs, if you just need to measure the battery charge capability once.
  6. You're a new member with low post count and no upvotes yet, the forum software is configured so that new members can't start posting (all of your posts have to be approved by a moderator at start before normal members see them) or sending private messages until you have reached a certain "status" within the community (enough posts & upvotes). This is to prevent spammers from filling the forums up with crap and harassing members with private messages. It's annoying but necessary. After you've made a few posts and/or get a few upvotes, the limitations are lifted and you're free to post without separate approval of each message and send private messages to other members. The actual numbers of posts and upvotes aren't public knowledge.
  7. esaj

    Lightest 20km/h wheel on the market?

    There's nothing "magical" about the 20700's having higher capacities: the cell itself is larger (about 20x70mm, vs. about 18x65mm for 18650's), so it has higher volume and thus more capacity with the same material structure/chemistry as the other (ie. comparing NCA 18650 and NCA 20700, the 20700 will have more total capacity but will also take up more space). (180650 is probably a typo in the above picture, I'm pretty sure they mean 18650) 18650's seem to be more common, and maybe cheaper at the moment because of economies of scale, but I think the Gigafactory is/will produce 20700's, so it might change in the future.
  8. esaj

    Lightest 20km/h wheel on the market?

    IPS i5 comes to mind, I think it was something like 8kg 7.5kg.
  9. esaj

    Control boards

    Yeah, that's it... looks like they're coming back then. Although from a quick glance it seems they now have a different board (30A, not 30B4), but at least something. Only problem is that the minimum order seems to be 500 boards... https://microworks.en.alibaba.com/product/60430498308-801473537/self_balancing_scooter_sourcing_codes_programming_board.html?spm=a2700.icbuShop.41413.8.336d7435UNeITO EDIT: Oh right, no idea what motors that works with, the motor driving code needs to be adjusted for the motor parameters, you can't slap just any 3-phase BLDC/PMSM motor on it and expect it to drive it correctly...
  10. esaj

    Control boards

    Could be wrong, but my guess is "no", while there are some models that use horizontal boards, I don't recall seeing any wheels with smaller than 15S (63V max) battery or maybe there was some 14S (58.8V max) less known wheel in the early days, so unless you can use batteries with that high voltages, there don't seem to be options. 36V (nominal, I suppose) battery is 10S (42V max). At least KS16's and (I think) Rockwheel GT16's use horizontal boards, possibly others. KS16's use 16S (67.2V max) and GT16's use 20S (84V max), newer KS16(S) boards might be difficult or impossible to use without original battery packs, as it seems they have some form of communication directly with the battery BMS's, so they might not work with a different type of BMS. Don't remember the name of the board that some DIY projects used (look for a 3d-printed wheel in this forum section), and I recall it was discontinued at some point (don't know if it has since become available again), but I think for that board you could ask the company producing the board to upload the firmware for either vertical or horizontal installation, it just comes down to which axes of the IMU are interpreted as being front-to-back, side-to-side and up/down.
  11. esaj

    Ever Buy Stuff That You Probably Don't Even Need?

    Sorry for being the usual pessimist, but... Even if they manage to build the thing and push the manufacturing costs low enough to sell it at a sensible price, one of the biggest hurdles will be getting enough game studios behind it to produce content (games). They're going against big names (Sony, Microsoft, Nintendo, possibly others, I haven't followed up on game consoles in a long, long time) that have very deep pockets and large market shares. Even if the system delivers what's promised, very few people are going to buy one if there aren't but a handful of games and no certainty if there are going to be more. I think that's what killed Atari Jaguar in the 90's (could be wrong though). But let's hope they prove me wrong EDIT: Checking on the Jaguar's demise, it's more complicated than just limited game catalogue (44 cartridge titles released over the entire lifetime of the console between 1993 and 1996, plus a handul more after the system was already discontinued, and for the CD-drive accessory, see the wikipedia quote below): while ahead of its time (being a 64-bit system in 1993!), the hardware was complex and a real headache for game programmers. Probably also a bit of a chicken & egg -problem, as the sales were never anything big, and producing triple-A -titles was expensive even back then, so probably many game studios didn't want to take the risk of entering the platform.
  12. Don't know if such are available off-the-shelf with correct connectors, but basically it's nothing more than a DC-to-DC -converter working with car battery voltages (typically something like 11-14V for most cars, depending on the car battery charge state) on the input-side and adjustable to correct voltage (67.2V for 16S or 84V for 20S) on the output side with current limiting. If I needed such, I'd just get an off-the-shelf DC-DC converter, adjust the voltage & current limitation, then add cigarette lighter connector on the input-side and GX16-3 (or whatever your wheel uses) on the output side. A typical car battery is around 70Ah at 12V nominal voltage = 840Wh, so you'd still suck it dry if charging a wheel with big batteries and the car wasn't running.
  13. I like the idea otherwise, but using a laptop to charge an EUC seems a bit of a no-go in terms of the battery sizes. A quick googling says that Macbooks have <100Wh batteries (if you use the entire laptop battery to charge the wheel, you maybe get something like from a couple of kilometers maybe closer to 10km of range, if you're really lightweight, the boost converter has good efficiency and you're not using a very powerful wheel), Chromebooks probably in the similar range and if you charge from a car, using the cigarette lighter -connector directly with boost converter would seem more useful than using USB-C somewhere in-between?
  14. Agreeing with you otherwise, but this is not an EUC, it's not Ninebot E+ but Ninebot Elite+, which is a 2-wheeled Segway-type device:
  15. To my knowledge, if the batteries have been sitting around for 2.5 years, the maximum charge capacity has most likely degraded, how much depends on their storage conditions and voltage (charge %). I'd try to get the reseller/manufacturer to replace the batteries, although they may require you to show that the battery capacity has degraded. Fully charged batteries (cells) lose capacity permanently over time faster, and especially if they're stored in elevated temperature, the loss is even greater. Degraded batteries cannot really be "rejuvenated", although some people have claimed that cycling the batteries (charge all the way to full, discharge all the way to empty) has helped a little (my best guess would be that in such a case it's some type of software "fuel gauge" in the device/battery BMS that gets to calibrate itself over the cycling, rather than the cells themselves regaining lost capacity?). If stored totally empty (or the voltage has dropped during storage to critical levels), the cells can get severely damaged (internal short circuit through dendrite buildup), at which point they may even become really dangerous (trying to charge such cells can overheat them and cause a fire/explosion). Typically the suggested more or less "optimal" charge state to store lithium-ion cells for prolonged periods is somewhere around 30-50%. Usually the BMS (battery management system) -board inside the battery packs draws some current, so the voltage will drop over time, and the cells also (very slowly) self-discharge, but I've never had to recharge the batteries when the wheels are unused over winter (typically around 7-8 months in storage per year), the voltage drop for high quality cells isn't that much. Temperature 40% charge 100% charge Table 3: Estimated recoverable capacity when storing Li-ion for one year at various temperatures. Elevated temperature hastens permanent capacity loss. Not all Li-ion systems behave the same. 0°C 98% (after 1 year) 94% (after 1 year) 25°C 96% (after 1 year) 80% (after 1 year) 40°C 85% (after 1 year) 65% (after 1 year) 60°C 75% (after 1 year) 60% (after 3 months) Source: https://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries For testing how much capacity they actually still hold, probably the easiest way would be to first discharge the batteries to empty and then charge them with a device that can measure the amount of watthours (or milliamphours) during charging, such as a Charge Doctor.
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