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trevmar

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Everything posted by trevmar

  1. The output voltage of the batteries will drop when they are hot, such as after a long, fast, ride. When I go uphill at full bore my batteries drop several bars by the top, but after a few minutes they cool and the number of bars increases. The battery voltage also drops during heavy output currents (such as going uphill) but that tends to recover much more quickly than they recover from the effects of heat.
  2. Yes, the extra batteries and tyres are heavy! The Unicycle really does present the best 'portable' option, IMO. They are still heavy, but the weight is manageable, especially for those with the handle..
  3. The MOSFETs are rated at 100V in the MiniPRO, so that is not a factor. But as WEagle95 confirmed, the interrupt handling is very poor in the firmware, and there is no exception vector should a CPU bus fault occur. This is bad programming practice, but something I noticed as soon as I started to dig through the code, as there are too few vectors in the boot table, and therefore many unhandled exceptions. Inmotion? I went for Airwheel S5. Even their S3 has 1000W of motor power, and twice the battery (520Wh) of the miniPRO (rated 220Kg load). It also has 14" tyres. I chose the S5 model with 19" OD tires, 3.5" wide, 1500W of motors and 680Wh battery. Problem is that the S5 has been removed from their range now. Mine came from April 2019 production (date was stamped on the outside of the box it came in). Still, these have the same brushless motors as the unicycles do (unlike the Segway I2 and X2 with their gearboxes) and maintenance ought not to be a problem. In fact, as I was watching the Gotway strip-down I couldn't help but notice the Nikola motor looked the same as the 12" rimmed motors on my S5
  4. Er, not really. In fact, the 59.5V charger puts about 25% less charge into the batteries than a 64V charger does. By charging a battery to only 4.0V per cell you reduce the risk of fire and increase the cycle life (the number of times you can charge the battery). But if you want the longest range, you need to use the 64V charger. I have both, and I normally charge my 310Wh miniPRO battery just to 59.5V, but if I am going on a longer ride I will use the 64V charger to 'top it up'. I use a 64V US charger I got from More4Mini. Look at Table 4 on this webpage: https://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries
  5. My thoughts exactly, although my feelings are based on the number of NCR18650GA 3500maH Li-Ion cells in the 20-cell 84V Gotway battery pack I can see in the tear-down video, with each '84V x 800W' bank of cells having an <18Amp max repetitive peak rating (peak not cited for GA series, but PF series is 18A peak for 5-6 seconds). With the 6 parallel cell-packs of GA they would get up to 15 x 6 = 90A, so 90 amps is feasible, especially if they over-rate the cells a little. The cells are reported to get very hot... (63-75 degrees centigrade). The LG cells in the MiniPRO 310Wh battery are only rated at 15Amp peak (x2) = 30 Amps peak... But that's still 1500 watts peak, which is 2 horsepower. It ought to be enough, I would have thought. I suspect that they cut the motors off at a lower value, to 'protect' the MOSFETs (or whatever). Or perhaps 35A is their cutoff, and they frequently bump into it.. I am pretty certain that v1.1.7 firmware allocates a lower peak current when it senses a 'mini' 234Wh battery pack instead of the 310Wh pack. ..
  6. As for miniPRO BMS: I built a pulsed Battery Tester capable of drawing up to 27 Amps out of the battery pack for half a second, with a 1/16 duty cycle so we don't overheat any components, or blow any fuses. The LG battery cells are rated at 10Amps continuous, there are two in parallel in the battery packs, so I am drawing more than that to make sure that I will see any difference under peak load between the battery packs. Here is a post where I gave the results I saw, there were no cutouts at 20 or 30 amps (pulsed)(>1500W). It looks to me as though shutdown is a control-firmware issue. https://forum.electricunicycle.org/topic/10991-minipro-batteries-4300mah-or-5700mah-boondoggle/?do=findComment&comment=189387
  7. I agree. I had to discard Swallowbot because it started to tilt back on the uphill roads around here, due to the 1.3.1 firmware underlying it. I found both 1.3 and 1.4 were unusable to me for that reason. How do you display current on the MiniPRO? I have tested the 240Wh and 310Wh batteries on my testbench, but have not been able to figure out a simple way of getting data from the controller itself (except via the JTAG programming equipment).
  8. I might add that the Americans with Disabilities act specifically instructs State agencies to permit the use of mobility devices, including 'Segway PT.' Look at the guidance in this DOJ brochure: https://www.ada.gov/opdmd.htm
  9. I have looked at how the miniPRO firmware is tied together, and one problem seems to be in how the control firmware assesses the size of the battery (mini or PRO). There are current measuring resistors on the control board, but they don't seem to do anything (because I made their resistance smaller and there was no difference in performance). I think a primary problem may be how the firmware handles the drop in battery voltage under heavy load or heating. I rode my new Airwheel S5 up to the same point where my miniPRO dislocated my shoulder, and I was amazed to see the battery indicator (the S5 has a built-in 4" LCD display) down at almost zero, until I stopped riding so hard and let everything cool down. The S5 has twice the battery size as the miniPRO (680Wh) so it is clear that my 200lb weight, plus the slope of a normal, if steep, paved road was putting extreme stress on the miniPRO. No wonder it kept complaining on the way up I just wish it hadn't dumped me unceremoniously on the way down. I measured the road at 12-13 degrees with the "angulo" app on Android. I found that one miniPRO wheel hitting a minor pothole or not-so-big rock can cause the machine to go into a similar shutdown sequence, probably because the miniPRO also senses similar 'overload' from that obstacle. It should, of course, be trying to allow momentary surges. I note that I saw a video of an EUC (a Gotway Nikola, I think) where the rider had connected a battery-current alarm at 90 amps, and it was being frequently triggered up an unpaved hill by the powerful motor in that EUC. As far as I can see, the miniPRO is limited to 20 amps max from its batteries, maybe as high as 30, but nowhere near 90, and it shuts down rather than powering through the momentary overloads.
  10. Well, I was running v1.1.7 when my ankle was wrecked and v1.1.9 when my shoulder was dislocated, as far as I can remember. V1.3.1 (which is also the basis for Swallowbot) is even less forgiving and I similarly discarded 1.4.0 pretty quickly (along with Swallowbot). The issue is that the MiniPRO does not give enough power to its motors to cope with fault conditions. To Segway/Ninebot, battery protection is more important than rider protection. It is the way the firmware is written, and Weagle95's last post here, the one announcing the release Swallowbot, identifies these weaknesses as being in all versions of Ninebot firmware, including Swallowbot. The miniPRO needs more batteries to safely carry a 'heavy' rider over obstacles. You can see this, for example, in the video below. Both the Inmotion EUC and the new Gotway have approx the same motor power rating, yet one fails at rocks on the hill, and one does not. This is exactly the problem with the miniPRO. From day one I have been saying that the miniPRO will throw me (200lbs) every time I run over a 1" ledge at the base of our driveway, but not throw my 150lb wife at the same obstacle. The miniPRO shuts off momentarily and drops the rider. Then it beeps continuously to announce its hardware has protected itself from a fault condition. However, the same heavy motor load is produced by rocky obstacles or a steep road (12 degrees) with a 'heavy' rider. Different EUC respond to these differently. The miniPRO really should not used by anybody over (approx) 170lbs. Which is roughly what its engineers designed it for (85Kg), not the 200lbs quoted by the marketing geeks (and which I weigh)... On a flat warehouse floor there is little risk of overload from 200lbs, however... (for more info check out the post at https://forum.electricunicycle.org/topic/13495-the-swedish-hill-test-inmotion-v10f-and-gotway-nikola/?do=findComment&comment=230709 .
  11. Very similar experiences to mine except I dislocated a shoulder and an ankle (and skinned lots of knees) before relegating the miniPRO to tasks like "warehouse floors." Although they have been discontinued and are hard to get, the Airwheel S5 is huge (75lbs) having a 1500W motor and a double-size battery, but is otherwise very similar to the miniPRO in design. Firmware is totally different, acting more like a traditional Segway than a miniPRO. Slow (17Kph max) and steady. It has 19" OD wheels with 100/100-12 4-ply motorcycle tires and has no trouble on any of the obstacles at which the miniPRO decides to switch itself off. Have only had it for a month, so I cannot say there are no hidden 'gotchas'. But very happy at the moment. One thing though - use their app to upgrade to the latest factory firmware (3.1.1.4). I have not tried it, but the slightly smaller (50lbs) Airwheel S3 is still being manufactured, and has all the benefits of the S5 except a slightly smaller battery (520Wh instead of 680Wh), smaller wheels, and therefore a smaller ground clearance and lower output power (1000W, 120Kg rated load). The outside diameter of the S3 wheels/tires is about 15" Yes, they are much more expensive, but small when compared to an injury. They are engineered and built very well indeed.
  12. If you look at the control board, you can see how the 3-phase motor in the wheel is fed from the full battery voltage by the two groups of 6 high power MOSFETS on the control board using Pulse Width Modulation. The limiting factor is motor dissipation, which seems to be around 350Watts, and the motor power will be dependent on the maximum voltage and power you feed to it. The miniPRO documentation says that each motor can feed 500W peak power to the motors, but I have seen evidence that the firmware cuts off at lower powers, due to the way it has been written. I note that the Airwheel motors might be worth looking at, some models (S5) are higher power than the miniPRO.
  13. And isn't that exactly the problem, @FreeRide, there is no definitive information about this product available at all.
  14. My wife weighs 70KG and has no problems at the same obstacles that caused the miniPRO to throw me (91Kg, 200Lbs).
  15. That's a pity. There was a lot of valuable discussion in the "Russian Hack" topic, even though Alex abandoned development to focus on other EUC/Scooters. Future Netizens would have found that discussion via Google if it had been left online. A great resource has disappeared, although I did capture some of it offline.
  16. I just bought an Airwheel S5. The 680W battery seems to last for ever But the bigger 1500W motor and 19" wheels don't give the degree of control you find on the MiniPRO, even though it does give safety (touch wood). I note that some riders report falling off due to the rather twitchy steering, but coming from a MiniPRO, you can almost go to sleep driving the Airwheel, pretty similar to driving a Segway I2/X2, except that the brushless motor 'cogs' a little from magnet to magnet, which, until you get used to it, makes standing still somewhat nerve-wracking. Although Airwheel make these devices to a very high standard, there is no support for the Airwheel platform, and I think the S5 has been discontinued. Mine left the factory in April 2019. Firmware is 0.0.03
  17. No, the weight limit set by the designers for the bigger battery is only 85Kgm, and they explain why in their blog, which you can read with Google Translate from here: http://bbs.ninebot.cn/forum.php?mod=viewthread&tid=4100&extra=page%3D1%26filter%3Dtypeid%26typeid%3D43 1/23 The 100Kgm is a number invented by the MARKETING folk stripping away the engineering safety factors, and then ruining the whole design by selling a smaller 234W-hour size battery than the design-team had intended. I weigh 90Kg, and twice the miniPRO has failed to support that weight, badly injuring me (firmware 1.1.7).
  18. The 3-phase brushless motors in the MiniPRO wheels consist of coils of wire wound around a circular iron stator and a rotor consisting of dozens of Permanent magnets, which move as the wheel rotates. Have you checked that none of the magnets have come loose? Skip to the nine-minute mark in the video below to see how to partly-disassemble the wheel motor without having to disassemble the whole miniPRO.
  19. Quick update on my Airwheel S5. I have ridden it around the hills where the miniPRO used to beep and push-back. With the Airwheel's double-capacity battery and double-sized motors (1500W) it now takes me comfortably up and down all the hills. It is interesting that after a lot of steep hill-climbing my battery voltage display (on the handlebar console) often drops back to 1-2 bars (from 6 bars). I ease off the up-hill speed (which is indeed comfortably faster than the miniPRO) and the battery bars gradually recover back to 5 or 6. I assume the batteries are heating up under heavy load, causing the drop in indicated voltage. That is neat! It is great to know how hard I am pushing the machine... Apparently when I get to 0 bars (if that ever happens, as it has a 20+ mile range) it will slow to a stop and tilt me back 10 degrees to tell me to get off and recharge the battery. Interesting behavior. But it is a 'stable platform'. You get on it and it moves you from point A to point B. Not fast, it prefers 10-12Km/h, with a limit at 17Km/h. You get on it, point it, and off it goes. You don't really have to ride it, just point it and lean forward/backward. The extra motor power handles my 90Kg easily. It is far closer to a Segway in handling, except that the brushless motor-in-the-wheels cogs a little with the 19" outside diameter tyres, and the platform does 'hunt' a little. Quite unlike a miniPRO. Anyway, it gets me nicely around the neighborhood, and it is totally quiet, allowing me to sneak up on the wildlife
  20. OK. I am looking for a volunteer to get thrown off a miniPRO onto our concrete driveway. Please form a queue. In other news, our new Airwheel S5 doesn't even pause when it comes to the same obstacle. I think the difference is that the miniPRO firmware is designed to protect the hardware at all costs. Not a good plan when this results in the riders getting hurt. The miniPROs should NEVER turn the balancing motors off without having fought to internal destruction to give the rider a chance to get off. If I am lying hurt on the road, I want my miniPRO to be lying dead beside me, not chirping happily to tell me it has protected itself from a fault condition...
  21. Please let us know what you think of the ES-6+ Thommy. The Airwheel S5 is totally different from the MiniPRO. Quite stately, actually. I can feel the powerful (1500 Watt brushless) motors hunting a little when stationary on flat bitumen. It likes to keep moving, not stay still. On grass and rough ground it is much more at home. This is going to take some getting used to... I really can't recall what the Segway I2 and X2 felt like. I need to visit our local Segway dealer again, and refresh my memory...
  22. I am still recovering from the dislocated shoulder I received a month ago when a miniPRO running 1.1.7 stopped working while going down a steep hill when I was testing the 243Wh batteries. Probably battery related, as I had been down the same hill several times with a 320Wh battery without failure. I weigh 90Kg. The miniPRO ended up beside me in the right hand gutter beeping continuously and with its motors depowered. I can't remember exactly what happened. I can't remember what happened when it broke my right ankle several months ago, either. There is no way the miniPRO could have ended up beside me in that way unless it had slewed around about 270 degrees. I have therefore bought an Airwheel S5 with the 16" wheels, bigger motor (1500W), and bigger battery (680Wh). A totally different experience (it is not a speedster). Let's see if that turns out more reliable in the long run. I have had too many failures from my MiniPROs
  23. The miniPRO really is very good engineering, when you look at it as closely as I have. There is a blog by Ninebot engineers which shows they really did contemplate a lot more than merely a "ripoff" or "copy." Unfortunately the firmware is inadequate to cope with the complexity of riding possibilities, and the inadequate motor power for a 90Kgm rider forced me to look at the Airwheel S5 - which is also beautifully engineered. I suspect you will be very happy with the quality of the ES6
  24. Hmm, that would be 4 parallel strings of 15 cells, each of 3300maH capacity. Pretty good if that's actually what they ship. Interesting that they use an RFID card to switch the device on and off.
  25. Good plan, Thommy! I am interested that they use a "brushless" motor now, as I thought the ES6 clones all used a brushed Taiwanese-import motor, to get the motor performance out of a small physically-sized motor. That is a good price for the battery pack. Maybe it uses fewer cells than the Airwheel? I haven't looked into the ES6 as much as I should have, as it is too wide to fit though our front door, and that ruled it out of consideration I am right this moment making a wire to connect my More4Mini 63V charger in place of the 67.2V charger which came with the Airwheel. There is a huge increase in battery life by taking the cells only to 4.0 volts each, rather than 4.2V, while charging. I don't need all of the battery capacity in normal use, and prefer the longer battery life. For longer trips I can still use the 67.2V charger There is a video showing how to connect the Airwheel BMS to a home-assembled battery pack, so I am prepared to maintain my own batteries once my unit starts to show signs of wear. The batteries are key to safety on these machines. That's why Ninebot keep trying to kill us all - by putting the cheapest battery packs they can find on the models they sell now
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