ArieKanarie Posted June 20, 2022 Share Posted June 20, 2022 Hello, Bought a cheap crashed V11 with hope of fixing it rather than buying a more expensive wheel. Regretting it at this point but I'm still trying to make it work. My issues is with one of the 2 battery packs. They are quite a bit out of balance so I wanted to just charge one pack to help it get even with the other one. The fuller pack charges just fine, but when I charge the lower pack the EUC world app shows a charging voltage that switches between ~2V and ~70V I'm guessing the BMS is dead/dying? I want to add a video but the file size is too large. Just imagine a value that stays on 2.6V, and every second it jumps to 70V for a very short time. Quote Link to comment Share on other sites More sharing options...
Tawpie Posted June 20, 2022 Share Posted June 20, 2022 What does a multimeter say the open circuit voltage of the 'bad' battery is? It might be too low to charge, in which case it would be a candidate for exile from the house and a trip to a battery expert. Quote Link to comment Share on other sites More sharing options...
ArieKanarie Posted June 21, 2022 Author Share Posted June 21, 2022 My multimeter says 69.1V, which is well within the normal voltage range Quote Link to comment Share on other sites More sharing options...
alcatraz Posted June 21, 2022 Share Posted June 21, 2022 I know it's not what you want to hear but personally I'd open the bad pack up and measure/charge the bad groups directly (single cell charger) and see if I can bring it back to life. If it went out of balance it's either bad cells or a bad bms. Quote Link to comment Share on other sites More sharing options...
ArieKanarie Posted June 21, 2022 Author Share Posted June 21, 2022 Yeah I figured. Luckily I have some battery building experience. Which screwdriver head is used on the battery packs? It's a triangle shaped one but does it have a special size or name? 1 Quote Link to comment Share on other sites More sharing options...
alcatraz Posted June 21, 2022 Share Posted June 21, 2022 I've only opened packs on V8/Tesla/MSX. Don't know, I'm afraid. Quote Link to comment Share on other sites More sharing options...
ArieKanarie Posted June 27, 2022 Author Share Posted June 27, 2022 Opened the battery up, very hard job. Â So, I like reaching a conclusion by eliminating. Â I swapped all connections from the good pack to the connectors where the malfunctioning pack is connected. It functioned well, charged and did not give those fluctuations in voltage. Which means the wheel is fine, problem is in the malfunctioning pack. Â Measured each cell group, they were all in the 3.39-3.41 range and the total voltages of the 20S1P sets were correct aswell. Which concludes that even Ãf there was a broken nickel strip connection, the pack would only lose capacity, not stop functioning completely. Â All pointers are now to the bms. The fuse was still intact. Maybe it's a (charging) mosfet that died, not sure how to test that. I think that swapping the bms for a new one will solve the problem. 1 1 Quote Link to comment Share on other sites More sharing options...
alcatraz Posted June 28, 2022 Share Posted June 28, 2022 This is good news, actually. The charging circuit is malfunctioning or being told to turn off (probably by the overcurrent/overvoltage circuits). At least the cells are fine = great. You could ride carefully on one pack until you get it sorted out. There are some ghetto mods you could do if you want to eliminate the bms alltogether but I don't want to suggest those at this early stage. Be careful working on the bms. It's always live as long as the pack is on it. Quote Link to comment Share on other sites More sharing options...
ArieKanarie Posted June 28, 2022 Author Share Posted June 28, 2022 The wheel is in pieces from a bad crash, I am waiting on a lot of replacement parts so no riding in this thing. I know an Inmotion dealer and he is able to order a new bms for me Quote Link to comment Share on other sites More sharing options...
ArieKanarie Posted June 28, 2022 Author Share Posted June 28, 2022 Unfortunately Inmotion does not want to sell the bms seperately Quote Link to comment Share on other sites More sharing options...
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