esaj

Moderators
  • Content count

    3,723
  • Joined

  • Last visited

  • Days Won

    127

Everything posted by esaj

  1. Depends a lot on your weight and battery size (don't know either), and other things, but the typical "consumption" is somewhere between about 10-25Wh/km (roughly 15-40Wh/mile). Guess you have a pretty big battery Because the batteries don't discharge to 0V. Most wheels stop (or at least warn that you're really low on battery) around 3.3V / cell. 84V wheels have 20 cells in series, so that's about 3.3V / cell * 20 cells = 66V ("0%"). 3.0V / cell is pretty much the safe limit, below that the voltage drops fast, but most wheels won't let you ride it that empty anyway. 2.5V / cell and the cells start (likely) taking permanent damage. Fully charged lithium-ion (for most chemistries, there are exceptions) is around 4.2V per cell, so for 20 cells it becomes 4.2V / cell * 20 cells = 84V. Great progress on your learning. Once you get the mounting down, start practicing stronger braking, you never know when you might need that. Another "handy" although not strictly absolutely necessary skill is crawling (very slow riding, walking speed and below), but it takes more time to learn. I rode through the harbor here during Neste Rally event (the walkways and bike lanes were all packed full of people, standing around and walking reeeaally slow) without putting my foot down, and had to crawl through the mass of people and sometimes stay in one spot for about a second, twisting the wheel left and right... well, not a good example where you'd need crawling (I could have just dismounted and walk the wheel through), but a more useful example might be when there's a narrow bikelane/walkway, you have people walking in front of you, a bike or more people coming the other side towards, and you have to wait before you can pass. Again, you could just dismount there, I prefer to crawl behind the walkers waiting for a proper opening to get pass
  2. Ouch, that sounds pretty bad. There's some pretty nasty looking cuts and bruises in this thread, hope everyone's ok or at least healing fast. I've had a few falls, but nothing that caused major injuries (my worst one was on the very first day on wheel back in 2015, head first to pavement, walked away scratch-free thanks to gear), this summer my only two mishaps leading to fall/dismount have been hitting rocks with the KS16 pedals, once on the first or maybe second ride with it, when I had to go around an unexpected obstacle through a rocky hillside (inflatable mattress put in the middle of the bikelane at evening due to some event the next day, "color obstacle course run" or whatever it was called), just dismounted there from a slow speed. Second time I fell on my back and hands (but had a backpack with my jacket in it and full gear, so no harm) when we went a bit "too offroad" (a small rocky path that would be hard to even walk on, nevertheless ride ), again from a very slow speed. Maybe about a month or more back, riding with a friend, I somehow managed not to see a smaller speed bump (that's very clearly marked!) on the road in a place where there's no bike lane or pedestrian walkway, pretty rare around here, and rode onto it at full speed: I don't remember how it happened, maybe I had the sun in my eyes or was concentrating on other traffic on the road. Doesn't look that bad, it's maybe something like 5-10cm at highest point (2-4 inch or so), but riding onto it at full speed with my knees pretty much locked straight (so no cushioning from there), it threw me straight up from the pedals. For a second there, I was pretty sure I'm going to get really banged up, but landed back on the pedals and kept going. Stupid, and lucky... My friend riding behind me (who had noticed the bump and slowed down ) told me that I took some pretty serious air there.
  3. Taking a quick peek at Aliexpress, even there the 1300Wh ACM is about 1200€ (roughly $1400), something's fishy with the price (assuming they really are new)...
  4. I just adjusted the output voltage, the actual balancing is handled by the BMS(s) inside the battery pack(s). There were four trimpots inside the charger, one for voltage, one for max current, one adjusted when the led showing charging/full will turn from red to green and the last one... I don't know, maybe it was for the partial charge. At least I think there were four. Anyway, I used a multimeter to see which trimpot affects the output voltage by turning each half or one turn (and turning it right back to original position if it didn't affect the output voltage). I recall I needed to go through them at least twice before the output voltage would start to change... If you try the same, be careful, the charger must be powered to see the output and there are parts running at mains voltage inside. To lower the chance of accidentally short circuiting something with the metallic shaft of a screwdriver, I actually used a plastic covered "screwdriver" that's normally used to adjust oscilloscope probe compensation: It's easier to see the output voltage changing upwards, because there are (or at least should be) large filtering/bypass caps at the output, they might keep the voltage high when the output should have already dropped (multimeters don't draw much current at something like 10M typical input impedance with voltage measurement). So if nothing happens with the output voltage and you've already gone through all the trimpots (and turned them back to where they were), try turning them in the other direction (clockwise vs. counterclockwise). Once you find the correct trimpot, adjust slowly and monitor the output voltage. Accurate high precision multimeter helps there, as you can see very small changes in the voltage, I used a HP34401a with 0.0035% base accuracy for DC voltage and 6½ digits, but it should be doable with a basic multimeter too (you just won't see as small changes).
  5. Don't look at the kilometer/mile-ranges given by the manufacturers, they're usually wildly inaccurate. The "consumption" varies a lot based on terrain, rider weight and your riding style, not to mention headwinds, temperature etc. I've measured consumptions between 11-12Wh/km (leisurely pace) and closer to 15Wh/km when keeping my average speed closer to 30's, in pretty similar temperatures/weather conditions, so just faster riding increased my consumption by about 30%!
  6. To me, the design looks like a mash-up of Solowheel Xtreme and newer Gotways. The tire must be the widest of any factory-produced models so far? No weight mentioned... if the motor/electronics design is solid and the price isn't anything insane, this could actually be a serious competitor in the power wheel-league. I had already accustomed to the idea that Ninebot has given up on new 1-wheel models
  7. I doubt it's the BT-antenna, wasn't able to find a picture showing the whole KS14C mainboard, but usually the wheels use a separate BT-module with the antenna built on the board (zigzagging traces), seen here next to the fan in KS16S: Maybe the module's dead? Most modules I've seen are common, cost a few euros/dollars and available in places like Aliexpress, just take care to compare the module with the ones available to get the correct kind. If it's directly soldered to the board like above, replacing it might be tricky though (Gotways seem to just use pinheaders). IIRC, Tina has left KS, but you could try @Diana@szkingsong.com
  8. The problem could come up with any wheel, but Gotways are likely more prone because the motor power is so high (something like 1500W rated/3-4+kW max?) and the motor will draw sustained large amperage during climbing, something like 50A or more constantly? That will heat things up over time. There are of course more factors at play (rider weight, speed, motor efficiency at different speeds, ambient temperature, connector quality, crimp/soldering quality, etc...). So far, I don't recall other wheels ever melting the cable sheathings or heating up the connectors enough to cause visible damage.
  9. Just spent a couple of hours on and off trying to find what's wrong with my half-bridges... My head hurts, but I finally found 2 missing wires and one misplaced resistor in total, that caused the 2nd bridge high-side not to open. Oscilloscope and signal generator would be nice, had to go with nothing but cheap multimeter and 555-timer circuit to produce 25kHz square(ish) PWM. Yeah, nobody probably cares, but I just had to vent a bit Now, I still need to build a 3rd similar half-bridge before I can try to drive a motor...
  10. The one I have has a small screw you turn at the other side of the strippers to control the grip (turn it too tight, and it will nick the strands though, too loose and it does what yours does, and the adjustment is pretty touch'n'go ). But the funny thing is that those are usually much cheaper than proper "manual" strippers. In this case, if it's for just for this single use, even knife could work, if done carefully (cut only part way through the sheathing around the wire, not all the way to the strands, then lightly bend the cut part around and pull the sheathing off), but if there's need to strip wires more often, proper wire strippers will save you a lot of headache in the long run Where I mostly use the "automatic" strippers is when stripping ribbon cables, as they can strip multiple wires in one go:
  11. Yeah, even eutectic tin/lead -solder (melting point around 183 Celsius) probably works just fine, as the joint shouldn't heat up in use that much if done properly (if you overlap the strands enough and there's a good connection, the joint might actually have even slightly lower resistance than other parts of the wire ). But using higher temperature solder can't hurt either (assuming the iron's hot enough to properly heat up and connect everything together). I just watched the video @Pard linked earlier, good tips and a well made joint, although since I like to nitpick , I have to mention that when he goes over the solder types, he calls the last one "silver solder" (but later on corrects that it's "metal working silver solder"). The non-leaded electrical solder he shows in the middle also contains silver (most lead-free electrical solders are tin/silver in varying ratios), the issue with the first solder he discards is that it's for metal working and has acid core, the silver itself is not the problem. Also, I had totally forgotten that soldering guns exist (mostly I've heard them called "quick soldering irons"), probably works fine for this type of soldering, but for electronics, total crap (that's why I've forgotten that they exist ). The tip is way too big for any precision work, and while they really do heat up fast (thus "quick soldering irons", usually with powers exceeding 100W and no temperature control), they also very easily overheat and kill more heat-sensitive components like transistors. But if @meepmeepmayer is only planning to use it for soldering wires and such, then it's also an option. Do the connections like he shows in the video and you can't go wrong.
  12. Not much progress with the welder for now, although the controller & software shouldn't need much work, just haven't gotten around to design & mill the board. In the meantime, I did take some boards apart from a broken old tablet (just a dead battery, but it was a Motorola Xoom from somewhere like 2011, so really not worth trying to find a replacement) and an old laptop (circa 2008, abandoned to me after I saved the data from the hard drive, already taken the battery apart for the cells a long time ago ). I expected that more modern computers (like... made in this century) have next to no usable parts in their boards, especially laptops, ditto for tablets in general. Turns out I was wrong, actually I got a good amount of 1206 10µF caps, tantalums and more heavy duty-SMD -mosfets out from those, plus a couple of thermal sensors, bunch of ceramic SMD power inductors and even a couple of ultra LDO (150mV dropout) voltage regs. Not that 1206 caps are expensive (something like 1 +- some fractions cent/piece at 100 pieces or more), but since they were there... Rest was mostly either too small to be useful, BGAs (Ball Grid Array) or too special purpose to be of use for me. Close up on some part of the boards. The large metallic looking (it's actually ceramic, I found out) part on the left portion is an SMD power inductor, part with marking "76" upside down is a diode. The black square is a BGA-chip, rest are SMD-caps (brownish) in various sizes from 1206 down to 0201 and likely some ferrites/small inductors (black ones), although one next to the BGA might be a resistor too (they don't put markings even on the resistors at that small size). I've mentioned the sizes that shrink towards dust speckles many times before, but once again, to give you some perspective: That's five SMD-caps side-by-side, starting from 1206 (3.2mm x 1.6mm or 0.12" x 0.06"), then going down to 0805, 0603, 0402 and finally 0201 (0.6mm x 0.3mm or 0.02" x 0.01"). That's where the names come from 1206 = 0.12" x 0.06", 0201 = 0.02" x 0.01". Similarly, in metric-sizes (it seems usually imperial sizes are used for components, even in metric countries), 1206 is known as 3216 and 0201 is known as 0603. What's confusing is that the naming partially overlaps (metric: 3216, 2012, 1608, 1005, 0603 etc, imperial: 1206, 0805, 0603, 0402, 0201) which could sometimes lead to problems (imagine thinking you're ordering 0603 in imperial-size and get it in metric... ). Probably that's why most people stick to the imperial size codes. Anyway, as you can see, it gets really small really fast. There's even one step smaller size (01005), but didn't have any of those in these boards (in general, they're not common, as even many automatic pick'n'place -machines can't handle that small). Here's a 0201 stuck on my sharp tweezers with the left over flux over the component: Now imagine that 01005 is quarter of that size (half the width, half the depth). And the set next to an XT60 to give more scale: I think it'll be a good while before I'm going down to even 0603's, not to mention the smaller sizes I think I could still mill boards for 0603's without the CNC tolerances / cutting quality becoming a problem, probably even 0402's (they're 1.0 x 0.5mm, and I often use 0.5mm traces when I need to), but lower than that, it might get tricky if there are burrs on the cuts and not to get shorts while soldering (no solder masks, remember ). I still have a broken older desktop mainboard lying around in the closet, might pick that apart some evening, lately I've been mostly just reading through Art of Electronics (a forever project, the damn thing's something like 1100+ pages, and slow to read as you really need to concentrate to grasp everything, although a very good book...).
  13. I don't know if fuses that warn you about getting near the limits exist, but that's actually a pretty good idea (assuming that the wheel itself has no warning of using "too much" power over extended periods). Ideally, a current sense -IC & some extra electronics (or a microcontroller) could be used for a warning system, but even the motor current sensor-ICs (ACS7xx, don't remember the specific model) on Rehab1's ACM-board he sent to me are partially bypassed with very small resistors (1 milliohm, if memory serves, and then likely compensated for in software), probably because they cannot handle the high current by themselves. I think @zlymex used some form of inductive current measurement (I'm not sure what they are called in English, just "inductive current sensors"?) that are touch-free and won't add resistance in the measured circuit: That's probably physically way too large though But with similar (smaller) sensor, a single motor phase could be monitored, and if "too high" (how ever much that is) averaged current is measured over some certain amount of time (1 second or whatever), the thing could start beeping...
  14. Pretty much... a couple of items that might become useful are something like: Something to remove the sheathings from the wires... knife might do, just be careful not to nick (too many) strands inside the wires A good quality wire stripper is expensive though. There are some cheapo "automatic" wire strippers that work well enough for most stuff, look about like this: Then either a soldering "helping hands" or just a couple of books on either side might work to keep the wires in place (they should not move about while you solder them): If you're using heatshrink or silicone tubing, remember to slide it into one of the cables before you put them together Braid the wires together as tight and as well as you can (there are multiple techniques, I won't go into debating what is best): and have them held (by the helping hands or books or other weights or whatever) so they're not being pulled. Put a little bit of tin on your soldering iron tip, take it to the braid and let it heat up a few seconds, apply more solder while keeping the iron there (the wires should wick the solder up), then remove the iron and let the joint cool down before taking it off from whatever's holding the cables, then insulate it somehow (heatshring/tape...). Don't go overboard with the solder amount, it won't help that much to have a huge blob on the joint and it will just prevent you from seeing the joint well as well as start to wick inside the insulation. To my (untrained) eye, something like this looks like a proper joint, you can still see the shape of the strands in the joint, but it looks shiny and smooth: If you need better instructions, there's probably loads of tutorials and videos up in the internet.
  15. Probably almost any decent hardware store carries pretty much all you need. A very basic soldering iron with no temperature control is probably good enough for this, if you have no further use for it, and shouldn't cost much (I've seen some basic 40-80W irons for <10€ here). Many alloys in soldering wires have high melting temperatures, such would probably be good for this (something like Sn/Ag = tin/silver or Sn/Sb = tin/antimony for example). Here's some generic table of ratios and melting points I grabbed from Google Image search (but there are many more alloys): Heatshrink/silicone-tubing or even just electric tape if you can't find anything else for covering the contacts is a good idea, you don't want them getting in touch with each other, otherwise the motor will lock up (very strong braking) and at the same time likely fuse the wires together. If the joint is good, it shouldn't heat up much more than the cables in general, so probably not that critical to get very high temperature solder like those with very high lead-content or that Au/Sn (gold/tin) -stuff that likely costs a small fortune and isn't readily available anyway. And if the entire cables then start to melt... well, you've got a whole new problem
  16. Nope, all the cables are in use while motoring or braking. My best guess is that the one that has began to melt has poorer connection than the others (higher resistance) and heats up more/faster than the rest under high currents.
  17. I made Wheelemetrics (for old Gotways and Kingsongs) a couple of years back, but have nothing to do with Ninedroid.
  18. I built a prototype welder for about 30€... Of course, I still need to build a proper controller for it, and still waiting for nickelstrips to see how it really welds, but have good faith it's enough (about 34 joules of energy, >10kW maximum spike power)
  19. Seeing vee73's motocross-track video, and how hard the wheel jumps up and down all the time, it got me thinking if it would actually be possible to build some sort of suspension into the wheel. After doodling a bit, I went into TinkerCAD (A free simple 3d-modelling tool that runs on your browser) and created a crude basic shape of what I was thinking (not really in scale). It's a kind of a "two-sided swing fork" (if that's even the correct term in english). Now, I don't know if this would ever actually work in real life (it could become too heavy, move the center of gravity too much upwards, simply break under stress etc.), I'm not a mechanical engineer. Or not much of a drawer, or modeler, for that matter, so I'm not even sure if you understand what the image is supposed to be As the motor is inside the hub, the wiring would also need to be able to withstand constant moving, the uppermost axle should never hit the tire (I put it too low in the 3d-image, it's not supposed to be touching the tire)... Lots of mechanical problems Edit: thinking it further, maybe the "swing arms" aren't even needed..? You guys got any ideas?
  20. Are you sure your new BMS isn't (again) a LiFePo-BMS? Those have lower voltages than "normal" lithium-ions, and the BMS would then be accordingly programmed to stop the charging at LiFePo maximum voltage. And like KingSong69 said above, DO NOT connect the batteries in parallel if the voltages are that different. The resulting current as the pack voltages start to equalize will be HUGE and will likely at least burn the connectors, if not melt the wires and/or make the batteries "vent with flame". EDIT: LiFePo's apparently have around 3.6-3.65V / cell maximum voltage, so probably it's not a LiFePo-BMS, as 76V (3.8V / cell) would already be above LiFePo maximum.
  21. Firewheel is a bit "special case" since the beeps start so early vs. the real maximum speed, but yeah, ignoring beeps is not usually a good thing. Firewheels are fun to ride but "safe" isn't a word I'd use for them, probably they're among the most dangerous wheels... no tilt-back, questionable alarms (it can be really hard to hear the voice messages with wind, and you get used to the constant beeping and pay zero attention to that), useless battery gauge (it would start showing 0% when I could still ride something like 3-8km out of around 20-25km total), no warning until the battery is almost completely depleted.
  22. Firewheels start the beeping around 18km/h, somewhere around 24km/h or so, some voice message plays (never made out what it says), and after 28km/h, it starts repeating "take care!". On an unshunted wheel, the wheel would cut out slightly above the final warning (29-30km/h?), Euc Extreme (from whom I bought mine) said that if accelerating faster, it would cut out before the message had time to play even once. With the packs shunted, I've taken mine to around or maybe slightly above 32km/h with no cutout, but probably no-one knows if and what differences there are between boards built at different times (we compared notes with hobby16, and his worked slightly differently, he'd taken his over 35km/h, but we're both very light riders), so there's no guarantee at higher speeds Mine didn't have any speed- or power-based tiltbacks, only tiltback and vibration after the battery was nearly depleted. Hobby16 said his wheel made this sudden fast acceleration (trying to tiltback?) somewhere around 30km/h... EDIT: Looking back at this thread, I'm basically repeating what I've already said above
  23. The talk about 3- and 6-pole motors sounded a bit weird, considering that what I've understood to be the poles in a motor are the coils and the magnets, often you see motor classifications with "pole"-counts for rotors and stators separately: Somewhere I also saw a calculator for motor winding where you gave the number of "poles" (coils) and magnets, the pole (stator coil) count should always be divisible by 3 though (for 3-phase motors). Either way would make most EUC motors more like 57-60 poles/coils and a few more magnets? Personally I've become convinced that (at least most) EUC-motors are actually PMSMs, not "plain" BLDCs, although the difference is "just" in the windings (sinusoidal vs. trapezoidal back-EMF, just hook your unpowered motor to an oscilloscope and turn the motor by hand), and I've seen the names sometimes being used interchangeably. PMSM would appear better suited for sinewave-drive/field-oriented control (FOC) -algorithms due to the back-EMF waveform and should give smoother acceleration and running, and probably more accurate control, which is needed in balancing? I've been meaning to dive deeper into FOC for a long time, and have read many application notes about the implementation, but so far haven't gotten around to build my own controller to see if I can drive the Firewheel motor Firewheel motor back-EMF: But I'm still not that certain on the terminology, and if the person writing the article is an electrical/electronics engineer, I'd expect him/her to know better than me It could be that the article was simplified, because most people arent' that interested in all the technical details and/or something was lost in translation.
  24. I wouldn't suggest to try this. Depending on the "speed" of the fuse (how fast it blows), a very significant current can still run through before the fuse blows (slow blow/time delay fuses can "allow" very high currents to pass without blowing for a short while). In my case, when I accidentally short-circuited a wheel battery over a multimeter (I thought I had the probes in the voltage-measurement jacks and didn't check, they were set for current measurement, oops), the full metal probe tip exploded with lots of sparks, the connector was destroyed and the fuse didn't even have time to burn before the tip was gone and the circuit was broken (or maybe the BMS cut the current, I don't know, either way, that brief transient current was enough to melt metal in an instant). To really test this, I think you'd need a proper DC load of high enough voltage & power dissipation or at least use a suitable power resistor / current sink in series with the meter to prevent too high current from destroying things.
  25. LG MH1's and MJ1's are NCA, as well as many others... in my observations, it seems that pretty much all >3000mAh 18650's are NCA, and to make a 208Wh (or 210Wh, depending on how you count) 16S1P, you need 3500mAh cells. So for example the 16S4P's with 820Wh (or 840Wh, depending how you count) seem to be always made with NCAs.