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trevmar

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About trevmar

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    Advanced Member
  • Birthday 11/14/1948

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  • Location
    California
  • EUC
    several MiniPRO (modified), Airwheel S5

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  1. 54V is pretty low for an unloaded battery. When charging the voltage should be 60V or 63V (depending on the charger). Run Alexandre's Android battery utility to see if you have any bad cells in that battery
  2. 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.
  3. 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..
  4. 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
  5. 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
  6. 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. ..
  7. 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
  8. 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).
  9. 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
  10. 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.
  11. 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 .
  12. 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.
  13. 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.
  14. And isn't that exactly the problem, @FreeRide, there is no definitive information about this product available at all.
  15. My wife weighs 70KG and has no problems at the same obstacles that caused the miniPRO to throw me (91Kg, 200Lbs).
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