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Showing results for tags 'battery bms'.
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I received my KS-18XL in June 1, 2019. This is my first wheel ever, amazing fun, been riding it for a month, 727 km done on it. I started reading about battery packs and how to keep it fresh for a long time. Should I charge to 100% or just 80%? Only then did I notice that my wheel would only charge to 85%, it would stop charging at 80.7 V, then later settle down to 80 V. Started debugging, maybe it's a faulty charger? KS-18XL has two 20s3p battery packs connected in parallel. I noticed that if only one is connected, the wheel charges normally to 84 V, if only another is connected, it only charges to 80 V and shuts off, the charger shows green light. The voltage would indicate that only 19 cells out of 20 are working. After communication with the seller and seller communicating with Kingsong we decide to try to rebalance the cells. I didn't know the cell balancing connectors are in the corner, so I removed the whole cover. If someone needs to balance their battery back, you don't need to open it all. I noticed the board had physical damage and first assumed it was me who had somehow damaged it during the disassembly. I was all dismayed so didn't document this part very well. Later after thinking more and more I realised it couldn't have been me, it had to have happened in the factory. 19 cells out of 20 were all showing equal voltage (3.8V), but the 13th cell was showing 0 V, exactly the same cell who's BMS had been damaged. Kingsong has told the dealer they would be sending me a new battery pack, so I am happy with the service, however it will just take a long time to reach me so the riding season might be over Will update if I do receive it or not. This story does sound awfully similar to @FrankFilmer incident. His wheel only charged to 70%, which I think is a huge red flag and indicates battery problems (maybe only 18 cells working out of 20). Finally, I think that our wheels are inherently very dangerous and had my board been damaged in another spot, or had I kept riding the wheel without paying attention I would have eventually gotten a cut-out or a fire in my home. The wheel doesn't have any advanced battery management system, it should watch the health of all cells and it should warn the user that the battery is malfunctioning, but there is no such warning for the user. I was riding with 19s3p and 20s3p battery backs connected in parallel. That can't be good. Always make sure that the wheel charges to 100% and actually check that it reaches the voltage it should be reaching. Just because charger shows green, doesn't mean all cells are working.
Winter coming.. ;-) Li-Ion batteries like warm weather - and perform much worse if used in cold weather, also deteriorate much faster in low temperatures. Thanks to riders from colder countries additional functionality of the Ninebot Z smart BMS had been found... Ninebot Z smart BMS is closely monitoring batteries temperature (please note that this is different sensor than controller temperature - see the difference on the pics below - controller temp is 16 deg.C while battery is 18 deg.C not only in terms of overheating, but also for too low limits... this may be disappointment to a few users who got stuck after longer break in the trip in cold weather, but in fact it is SAFETY feature protecting rider from over current / switch off during the ride, and also protecting batteries against destruction (use of Li-Ion cells in low temperatures destroy cells quickly) So - If the battery temperature falls below certain limit (not yet found - but probably 0 - 5 deg Celsius or similar - please post your comments) Z10 will not turn ON ... So - this is general info for ALL unicycles - in winter conditions - never leave it in the car trunk or any other place with temperatures below room temperature - keep it warm before the ride - during ride battery will heat itself, and after the ride - put it back to the warm room. Do not make longer stops outside if weather is cold, for sure if it is below 0 Celsius.