Rotator Posted February 20, 2016 Share Posted February 20, 2016 On 18 de febrero de 2016 at 8:27 PM, chriscalandro said: you should update to 1.3.5. It's a solid release and miles better that 1.2.2 3000+ km without any unexpected problem is rock solid release. Moreover, there was people in this forum who will back to 1.2.2 if they could. So...I don't know. I would like to upgrade it, but I'm a bit scared of the unexpected shutdowns and fried motherboards of last updates. May be later... Link to comment Share on other sites More sharing options...
esaj Posted February 20, 2016 Share Posted February 20, 2016 Related to the bridges seemingly failing in conducting-state (hard to turn tire even with power off), and I don't think Ninebot-users have done the shunt-mod on their BMSs (at least I don't recall ever hearing anyone shunting a Ninebot), but seeing that there's an increased risk of the bridge failure with Ninebots, I'd suggest not to ever shunt a Ninebot. If the BMS cannot cut the power, your wheel becomes a ticking timebomb after you faceplant due to bridge-failure, as the battery is also likely short-circuited at that point and will dissipate most of the power (at least several hundred watts if not kilowatts?). How long will that take for it to reach the critical temperature, seconds or minutes? Link to comment Share on other sites More sharing options...
dmethvin Posted February 21, 2016 Share Posted February 21, 2016 17 hours ago, esaj said: Related to the bridges seemingly failing in conducting-state (hard to turn tire even with power off), and I don't think Ninebot-users have done the shunt-mod on their BMSs (at least I don't recall ever hearing anyone shunting a Ninebot), but seeing that there's an increased risk of the bridge failure with Ninebots, I'd suggest not to ever shunt a Ninebot. If the BMS cannot cut the power, your wheel becomes a ticking timebomb after you faceplant due to bridge-failure, as the battery is also likely short-circuited at that point and will dissipate most of the power (at least several hundred watts if not kilowatts?). How long will that take for it to reach the critical temperature, seconds or minutes? With a big battery pack I wonder if it could vaporize the supply wires or BMS traces before the batteries reached a critical temperature and vented! Even if that happened, the amount of damage inside the unit would be massive since a lot of other wiring and plastic would be melted. Link to comment Share on other sites More sharing options...
esaj Posted February 21, 2016 Share Posted February 21, 2016 2 hours ago, dmethvin said: With a big battery pack I wonder if it could vaporize the supply wires or BMS traces before the batteries reached a critical temperature and vented! Even if that happened, the amount of damage inside the unit would be massive since a lot of other wiring and plastic would be melted. Those things are always possible too (and "preferable" when comparing with the batteries going up in flames ). In Vee's burnt MSuper-board, the legs of the mosfets themselves had actually melted/blown away Guess those LiPos have so low internal resistance, that the currents can get really high (hundreds of amps?). Link to comment Share on other sites More sharing options...
SlowMo Posted February 23, 2016 Share Posted February 23, 2016 On 2/20/2016 at 2:04 AM, esaj said: Related to the bridges seemingly failing in conducting-state (hard to turn tire even with power off), and I don't think Ninebot-users have done the shunt-mod on their BMSs (at least I don't recall ever hearing anyone shunting a Ninebot), but seeing that there's an increased risk of the bridge failure with Ninebots, I'd suggest not to ever shunt a Ninebot. If the BMS cannot cut the power, your wheel becomes a ticking timebomb after you faceplant due to bridge-failure, as the battery is also likely short-circuited at that point and will dissipate most of the power (at least several hundred watts if not kilowatts?). How long will that take for it to reach the critical temperature, seconds or minutes? Is this damage caused by the bms not cutting off during excess load? Link to comment Share on other sites More sharing options...
Chriull Posted February 23, 2016 Share Posted February 23, 2016 Seems that these are current sensing resistors, that are charred - but is not really to be seen on the foto? Could be "just" an overheat issue - i would assume, that the mosfets would die before the resistors? Imho BMS cut off should be the last safety measure, that the cables/boards/battery cells don't start burning. To keep excess load under controll should be the duty of the firmware in combination with a good design. Link to comment Share on other sites More sharing options...
SlowMo Posted February 23, 2016 Share Posted February 23, 2016 22 minutes ago, Chriull said: Seems that these are current sensing resistors, that are charred - but is not really to be seen on the foto? Could be "just" an overheat issue - i would assume, that the mosfets would die before the resistors? Imho BMS cut off should be the last safety measure, that the cables/boards/battery cells don't start burning. To keep excess load under controll should be the duty of the firmware in combination with a good design. Here's the burn mark on the battery pack. There might be some more inside the blue plastic cover but I have not opened it yet. Link to comment Share on other sites More sharing options...
Chriull Posted February 23, 2016 Share Posted February 23, 2016 2 hours ago, SlowMo said: Here's the burn mark on the battery pack. There might be some more inside the blue plastic cover but I have not opened it yet. if you look at the BMS board picture in this charred part looks like one of the flaps connecting a cell with the board. Strange that this got as hot ... could be anything from an overheated cell, bad contact or whatever blown in the BMS. And this caused by some excess load from the MB/motor? Link to comment Share on other sites More sharing options...
SuperSport Posted February 23, 2016 Share Posted February 23, 2016 A bad solder (Tack Weld) connection will cause burning like that. I wonder if it started by the issue posted here: Maybe the vibration/wear caused the tack weld to come free, which in turn caused the heating and burning. Or with enough pounding, I could see the Inner and outer layers of a cell coming together. + and - Might be time to actually USE the Double Sided Tape installed on the side of the NineBot battery to hold it still. Link to comment Share on other sites More sharing options...
musk Posted February 23, 2016 Share Posted February 23, 2016 6 hours ago, SuperSport said: 6 hours ago, SuperSport said: Might be time to actually USE the Double Sided Tape installed on the side of the NineBot battery to hold it still. Burn! ... about a burn. So it's a Burn burn. Link to comment Share on other sites More sharing options...
SuperSport Posted February 23, 2016 Share Posted February 23, 2016 19 minutes ago, musk said: So it's a Burn burn. Yep Yep Link to comment Share on other sites More sharing options...
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