esaj

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Everything posted by esaj

  1. 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...
  2. Don't know about hydroplaning with an EUC (tire raising above the water on the street and losing control), but I think I saw a calculation somewhere showing that to hydroplane with a bicycle, you need to pedal closer to 200km/h (about 125 miles/hour). Of course EUCs use wider tires so that might affect at least somewhat. Never paid any attention on the rolling direction markings (except in car), but I don't think they matter that much with the speeds EUCs can achieve.
  3. I think it has been mentioned somewhere in the forums that GR16 gears were prone to wear out, or maybe it was Facebook back in the day. Don't go there often, hate the platform, I don't even actually know what's going on in the EUC group there, having hard enough time trying to keep up with forums posts. Austin Marhold (a guy who used to make a lot of noise in Facebook, lived at least at the time in Shenzhen and rode many wheels, claiming to have broken something like 30 wheels in 2015) once said he loved GR12 (the smaller version), but had to buy many broken wheels to get spare parts and change the gears in the motor (or entire motor?), as it broke down... I think he said something like the gear sets/motor had been replaced 4 or 5 times at some point, but his riding style wasn't very sparing anyway for any wheel And I think he also claimed to be able to run off a 30km/h cut-off, so probably he tended to exaggerate things a bit too?
  4. How early is too early? I haven't been able to reach the speed limit with almost 50km trip (starting with full battery), at the end of the trip the battery charge was somewhere between 30% and 35% (but I'm light weight). Never ridden it below that yet. My KS16S is still on firmware 1.0 (the firmware for the S-model is different than other KS16's). The KS16B starts the warning after 25km/h at 50%, but it's still on firmware 1.23 and I think someone said that 1.25 dropped the limitation to begin at 30% or 25%. When the B drops below 50%, it just plays the warning sound above 25km/h, but didn't start to tilt back, I haven't really tried to push it to higher speeds to see if the tilt-back speed is also lowered, probably someone with more experience with the earlier KS16's knows... I'm not sure what is the lowest battery percentage I've driven the B so far, probably something like 30-35% too. Haven't been able to ride much with either the S or the B in the last week, as I've been busy with work and the weather has sucked. As for the 80% power warning, no idea. When I started riding the KS16S, I had the alarms set at lower values and had still the "voice commands" on or whatever it's called in the app. Basically the warnings come as spoken messages instead of different beepings. With that, I think at one point accelerating fast after hitting a pothole and going uphill, I heard something else than the usual "please decelerate", but I'm not sure, I first thought it might be power-related, but it could have been that I had passed the highest speed warning before tiltback or something like that too. Since then I've changed the warnings to beeps, but haven't noticed anything else except the speed warnings.
  5. I didn't know electric unicycles existed until a couple of years ago. In spring of 2015 I was chatting with a neighbor about motorcycles, and how expensive a hobby they are here. I then started thinking about other options, and thought of Segway. The price really turned me off, but my searches also brought up Ninebot ads. Not that long after that, I had found this forum, placed an order on a domestic reseller of Ninebots, but as I was anxious to try the damn thing, I ended up buying a used generic from Vee (nowadays known as EUC Extreme). I also later on bought his used Firewheel (the one he uses in his early videos) and canceled the Ninebot. My starting points and early journey are documented in excruciating detail here:
  6. Well, you probably saw my earlier post already, but what I mean by "same code base" is that the basic code driving the wheel functions is the same, but they have different builds of the same firmware where certain parameters of the firmware are changed to match each different wheel (ACM, MSuper, Monster, might be also different for 67V vs. 84V). Call it "configuration"? Yeah, one can dream... Someone actually posted a shop selling Firewheel-boards (or clones of them, although apparently Firewheel board is a clone of SBU ), and the shop also mentioned that they have the firmware source code available. Didn't contact them myself (at least yet, I've got my hands full right now with all my own stuff already ), but might try in the future. It's no Gotway/KS/Inmotion/whatever-big-name firmware, but it would be interesting to see a more "professional" firmware without having to just guess how they're made. Of course it could also be that the big-names use totally different algorithms for driving the motor and calculating the balancing loop.
  7. Ah, I read it through earlier, but missed that detail. I can see the cost-benefit point of making only a single board instead of two or three different ones, and like has been stated before, we aren't seeing boards blowing up left and right, so it's probably not that big of an issue. But it does have it's problems, like a tired worker doing an 12-hour shift or whatever, and mistakenly placing the wrong board on a wheel, as they all look the same... although I'd expect they at the very least try that the wheel turns on and balances before shipping it off Likely it's the exact same board on every wheel, and the firmware's the same, only certain parameters are changed to match the motor inductances and other parameters. One of those parameters could be the current limit (if that's what is actually causing the bug), so it might be correct in Monsters and wrong in ACMs/MSupers.
  8. Well, one thing's for sure after seeing that picture: Monster, ACM and MSuper all share the same board (maybe with some slight component changes, but otherwise that's exactly the same board as Rehab1's dead ACM board he sent me). So probably also the firmware code base is the same, which could potentially mean that NEW (post end-of-April) Monsters could also be affected. I'm still leaving the "maybe Monster" in the topic name... EDIT: I was under the impression that Gotway was using TO-247's in Monsters, but those are the same TO-220's as in the ACM. I also bet that those are the exact same IRFB4110's as in ACMs and MSupers. So looks like KingSong (KS16S, IRFP4368) and Rockwheel GT16 (IRFP4110, TO-247 -version of the Gotway mosfets) are the only ones using heavy-duty mosfets..? Not that heavier gauge mosfets would help with melting wires and firmware bugs...
  9. Thanks, but in reality I had lots of help from the Garage Elf, he for example sawed small slivers at both sides in of the ends of the side plywood boards, so that the side boards slide inside rack rail profiles, and were then fastened with three M6 bolts and "strike-nuts" (don't know if that's the correct English term, the kind of nuts that you drill a hole for and then hammer inside the board so the teeth hold it in place): It's really sturdy, the 10kg (22lbs) power supply unit is held only by the four bolts on the front and nothing budges in the least bit. I think the desk will give in before the rails or the cabinet Luckily it has a sideways support underneath, otherwise the table top would probably already start to bend from all the weight... Not the cheapest of the cheap, but nothing really high-end either: an Ayoue.. .Aoyue... "vowels" INT968+. The few people who have those said that they've worked just fine and should be enough for hobbyist use: http://www.aoyue.eu/aoyue-int968a-repairing-station-hot-air-soldering-station-3in1-with-tweezer.html I haven't even opened the box yet (and keep reminding myself that when I do, I have to remove a screw on the bottom that's there for transportation, but must be taken off before use). Also ordered some extras, like a pick-and-place vacuum-piece that replaces the fume-extractor (already got a fume-extractor, plus I have a 100CFM = 160m3/h SystemAir industrial fan duct-blower in storage, if I can mount it and need more suction ) and the tweezers (the link says comes with tweezers, but not these): Should be handy for removing SMD-resistors and such, but might also be total crap Yeah, actually I think the pre-drilled holes might be better (at least when using standard-sized equipment, ie U/unit-heights), but I got the rail for free and this was a good opportunity to put it into use. Like I mentioned in the "ever buy stuff..." -thread, right after the cabinet was built, another friend offered me his 12U floor-rack (the wheels can be removed to use it on a table or such) for one beer, so it's currently sitting in pieces the guest room (along with all the parts cabinets and random this and that) waiting for me to get around to figure where I put it.
  10. I call your Ikea-furniture and raise you a hand-made shelf with rack-mount: I've been a busy little bee lately, although everything's still not finished, plus I've had to put all other projects on hold... The lights are controlled from the rack-mounted front panel, which also sports some short-circuit protected outputs from the ATX driving the lights: One of the 12V outputs is short-circuited through a patch-cable, just for show. All the stuff behind that panel is built from left-over scrap through-hole parts I had onto matrix-boards, couldn't be arsed to design actual boards I recognize the irony that I use ad-hoc designed boards and scrap parts, when I usually spend days doing prototypes on designed & CNC-milled boards from pristine components... Especially since this is supposed to be semi-permanent, whereas many of the prototypes get scrapped soon afterwards. There's a couple of extra holes for stuff I was planning to do later. I had trouble fitting the old large light fixture on the desk, so instead I took apart an old desklight (for the swiveling frame), and bolted a couple of 10W power leds onto a aluminum flat: I had to add some heatsinks as those things heat up a lot The measurement side on the left (seen in the first picture) has a piece of board with two led-tapes & 3 x 3W power leds. Soo much easier now that I actually see what I'm doing The lights are driven by constant current sinks, using power mosfets and op-amps, and the current can be adjusted with the knobs on the front panel and turned off with the buttons. Still long ways to go, I've got to move the CNC, clean up a lot of stuff, get my new hot-air station that arrived today set up etc, but it's getting there.
  11. No, the actual wattage you're using at any moment in time is dependant on many factors, your weight, speed, acceleration/deceleration, going up and down hills, air drag... You can't calculate your "battery consumption" from the motor nominal or max power. On a level flat road at steady speed, you use a lot less power than accelerating or going up hill, when braking or going down a hill, you're actually (slightly) charging the battery. A stronger motor will help climbing hills, maintaining higher speeds and accelerating faster, and for heavier riders is a must, as for example climbing hills, the power requirements go up fast with rider weight. For "typical" numbers, I'd say the average consumption is somewhere between 10-25Wh/km or 16-40Wh/mile (more weight and/or higher speed & accelerations = more consumption), depending on your riding style, environmental factors and terrain.
  12. Thanks! But wouldn't that require you to have a KS16 for mold? Can't rep you, I've had to play catch up with a lot of threads today and looks like I've run out for today.
  13. Yeah it folds up. I have the KS16S sitting on it now, fits nicely:
  14. On the actual topic of buying stuff you probably don't even need... I was about to order a 21U floor rack cabinet from Thomann, as I had to order other stuff there and would have gotten it with free shipping. Of course the model I wanted was out of stock, so started building a shelf-thingie with built-in 19" rack from rack rails (11U high) to better use space in my work desk and get better lighting etc. Right after it was built, with lots of help from the Garage Elf, another friend told me he has a 12U rack and he'll sell it to me for one beer, so practically free... Don't know if that counts as "buying", but... I have exactly one rack-mount device, that's 2U high, and now I have the space for 10 more such units So instead of saving space, I'm (1) likely going to end up with even more space problems, as now I have to find new space for the component lockers (can't put them on top of the shelf, the top-most lockers would be too high to easily reach) and the second rack and (2) will "need" to start buying more rack-mounted equipment to actually make more use of the racks Although I'm not sure on my budget what devices those would be, a PSU capable of providing voltages as high as the unicycle batteries (67.2V / 84V) would be nice though. It's a vicious cycle... does buying a larger house to fit all your stuff count as "buying things you don't probably need"? Still "work in progress", the stuff laying on top and front of the shelf isn't supposed to be there, I'm just trying to figure out where to put everything And need to build lighting under the shelf from some led-tapes/power leds, as well as draw some more power cabling there.
  15. Should the topic be changed to say something like "Dangerous sudden oscillation with MSuper & ACM made from May 2017 onwards" (until they get it fixed and we can establish from where onwards the work again)? Or even stronger words, something like "Do not ride with MSuper or ACM made in May 2017 or later"? Or maybe just start a new thread with description of the problem and instructions on how to identify the actual production date and not just motor codes.
  16. The time limit was changed recently. Don't remember the actual times, but I think normal users are allowed to edit their posts only a couple of days after posting. I edited the first post to contain your warning.
  17. AFAIK, the IPS is not stronger than MCM3/4, at least the older IPS's apparently used the maximum power number in the marketing, rather than nominal, IPS T350 is 1000W max, nominal could then be maybe 400-500W. MCM4 is is 800W nominal (peak power might be something like 2kW?). On the other hand, you rarely hear anyone complaining that their IPS has broken down (maybe with the exception of IPS Zero?). In general, I'd consider IPS a more reliable brand than Gotway, but also more conservative (less speed, less power). I guess the reliability of older Gotways was better. MCM4 doesn't (probably) have enough power to suffer from the melting cables-issue, and the oscillation problem seems to be limited to newer ACMs/MSupers (maybe Monsters?) built recently (May 2017 onwards?).
  18. 6.70€ at Thomann (Germany), of course without shipping, but I was ordering stuff from there anyway and threw one of these in the basket too: https://www.thomann.de/gb/millenium_gs2001a.htm
  19. Do they have version control for the firmware at all? Maybe they thought they had the bug figured out and fixed, but it makes me wonder... why not just roll back to a known good version? If they can't reproduce the problem themselves, I hope they aren't just blindly trying to fix it without testing.
  20. Depends what you consider inexpensive... small battery or step-down to power from the wheel batteries (or 12V or 5V off the board, if accessible?) + Arduino Nano -clone + beeper + sensor shouldn't cost much, usually it's more of an issue with getting them encased properly and fitted inside (or outside) the wheel. Calibrating the measurement with an NTC-resistor might be a bit difficult, but you can get K-type thermocouple that's good up to around 1000C + board with chip for reading it with cold junction compensation (MAX6675, I got them somewhere, at least one in my reflow oven) for reasonably cheap. The thermocouple seems to be fairly accurate (well, as far as I can tell with another cheapo measurement device, a pistol-type infrared thermometer), but chips' precision is 0.5 or 1C (forgot which). The length of the thermocouple cable might be an issue though (I didn't shorten it).
  21. Don't go above 5A unless you plan on changing the charge port connector also, the GX16 can heat up and melt with high current and is supposedly rated for 5A max. With that said, I've been charging both the KS16S (840Wh) & KS16B (680Wh) with two 2A chargers connected through Charge Doctor V2 (so 4A total) without problems. Nowadays I mostly charge with the original KS16S (2A) charger, and a similar, but "only" 1.75A Firewheel charger, so 3.75A. The charger that came with the second hand KS16B (same charger as the KS16S) started making a crackling sound and heating up, so I stopped using it and threw it in my "investigate at some point" -pile I also have a 4A Gotway charger laying around somewhere, that would probably work too.
  22. Yeah, I can't claim to know that they use lower frequency for the actual PWM either, it could be also just something (windings) resonating in the motor at lower frequency. The wires going from PCB to motor, it has happened in many Gotways. Earlier problem was that the connectors heated so much that the solder melted and the wires could come off during riding, now that they've switched over to heavier duty connectors (and crimping + soldering, apparently), the wire insulation has melted and shorted the phases on at least a few riders. Yeah, it's on the PCB. Only board using ferrite beads in series to mitigate ringing on the gates I've seen so far has been the Firewheel / SBU -board, which doesn't even have paralleled mosfets, Rehab1 sent me his dead ACM-board (the MCU's fried), there they seem to use just resistor with diode in parallel (probably to speed up turn off?) for parallel mosfets (the gates are tied straight together, no resistors in between), and no ferrites. But the gate drive is completely built on the board, just PCB traces and SMDs in the path. You're probably right, the stray inductance of the wiring is likely very low in comparison to the actual motor winding. But still, with high current spikes (mosfets turning on and off, direction of current changing), could the skin-effect come into play if the frequency is high enough? As in, would the wires start to "act" like a thinner wire, as the current flows closer to the surface and not through the entire cross-section of the wire? Or maybe I've misunderstood the whole concept of the skin-effect According to the Powerstream AWG-table, the 100% skin depth for solid 14AWG is 6.7kHz and 11kHz for 16AWG, of course the actual wires use multiple conductors, and I don't know how the surface-area / cross-section carrying the current should be modelled then...
  23. It's for my capacitor bank spot-welder, a project that has been dragging for quite long, as for example I had to wait 3 months for the caps (that should have been originally in stock within a week from order), but also because I've had lots of other stuff to do recently (like riding )... Even a single wire has stray inductance, and I used some wire inductance calculator (using just the diameter/circumference of the cable, which probably isn't exactly correct) to get a value of 525nH per cable (two 50cm cables in total, welding prongs at the ends). The current changes fast with the spikes (basically shorting a 470000uF bank at 12V max over the cables, pieces to weld and paralleled mosfets), which in simulations caused over 100V spike at turn-off, probably that would fry the low-side mosfet-switch bank (made from 5 x 40V, 190A/1080A IRFP2804 mosfets in parallel), so I had to order some high-amperage fast recovery diodes that can freewheel and keep the voltage from rising too much and am changing the switch-bank to use actual gate drivers instead of just a push-pull array to speed up turn-on / off and looking into using ferrites and gate resistors to "correctly" handle the parallel gates. But I'm still not sure if the stray inductance is correct, or if the diodes are enough (3 x TO-247 RURG3060), or if I need place them just in reverse parallel next to the cabling or only/also at the switch-bank. I'd rather play it safe than end up blowing the switches (or the caps)... Further discussion of that probably belongs to off-topic.
  24. I don't know if anyone has actually measured it from the gate-drivers, but it seems the wheels use lower PWM-frequency, <10kHz... this is mostly based on the sound emitted and someone did run it through a spectral analyzer to see the peaks, the fundamental for KS16 was somewhere around 5.5-6kHz, if I remember correctly, with some spikes at higher harmonics. If I had to guess, I'd say they use lower frequencies to minimize switching losses (mosfet passing through the linear region at turn on / turn off) and maybe to minimize the skin-effect on the longer wiring going to the motor? But I haven't got a clue how the parasitic inductance of such cables should actually be calculated, it's multi-stranded but not Litz-wire, so I don't know if you should just take the outer diameter or model the shape of the strands pushed together, as there's more surface-area then... probably doesn't even matter that much in the wheels, but I have my own reasons for being interested in the parasitic inductance in longer thick wiring (pushing up to around 1000A / 1ms pulses through a 16mm2 / about 5AWG -cabling, leading to very high di / dt ... )
  25. The percentage may not be that trustworthy as an actual voltage measurement. Still, it sounds a bit odd that the voltages would have drifted that far apart in just an hour. Faulty cell in one of the packs? I don't know about how Gotway cabling, but I'd expect them all to be connected on the charging side, so that should work. Do note that if there is a faulty cell in one of the packs and it drops the voltage to a lower value once taken off charger, it will spark again when you connect them. I'd suggest measuring the pack voltages to check if one of them is clearly at a lower value. The anti-spark connectors should not be used between battery packs, only between the mainboard and the packs. Again I don't know how Gotway cabling goes, but I'd presume there's a single connector going to the mainboard. The anti-spark connectors have low-value resistors, that can take the very momentary high power dissipation when the capacitors charge (fractions of a second), but probably not for a longer while if between two packs in different voltages (or they don't have enough time to balance the packs when pushed in). If you feel unsure doing it yourself, something like a local RC-shop will probably be happy to exchange the connectors for you, for a small fee.