alcatraz Posted June 28, 2021 Share Posted June 28, 2021 (edited) Hey everyone I made a DIY pack for my V8 that I still use to this day. One hurdle was that I had to use an original bms to get it to hook up to the wheel. Now I ride a Tesla v1 and I'm curious if Gotway wheels are simpler. Can custom bms's be hooked up to the wheel? I'd like to install a bms with bluetooth so I can monitor the pack but I want charging to work like before and also the wheel to operate normally. Can it be done? Has anyone done it? Did it require tons of modding? Obviously I would not allow the bms to control the output. I'd connect the control board directly to the cells. Edited June 28, 2021 by alcatraz Quote Link to comment Share on other sites More sharing options...
Boris Lämpel Posted June 28, 2021 Share Posted June 28, 2021 Gotway should be much easier. 1Radwerkstatt.de did it with the Nikola 100V. They use the xiaoxiang bms to control the cells and charging inlut. The BMS cannot cutoff the output, only the charging port. It is accessable via bluetooth. 1 Quote Link to comment Share on other sites More sharing options...
Chriull Posted June 28, 2021 Share Posted June 28, 2021 1 hour ago, Boris Lämpel said: Gotway should be much easier. 1Radwerkstatt.de did it with the Nikola 100V. They use the xiaoxiang bms to control the cells and charging inlut. The BMS cannot cutoff the output, only the charging port. So if one only BMS cuts off the charging port it gets overcharged through the output by the other bms?! Has chris found a solution for this problem? I'd personally prefer having the possibility to watch/supervise single cell voltages than this "automatic overcharge cut off" - one just has to be aware of this and regularly check the batteries before and after charging. Quote Link to comment Share on other sites More sharing options...
alcatraz Posted June 28, 2021 Author Share Posted June 28, 2021 (edited) I'd only use one bms myself. One downside is that you'd probably have to make two 42v packs and hook them up in series to get 84v. It reduces complexity but you need both packs at all times. Have you noticed that generic bms's physically have a huge set of large mosfets that wheel specific bms's lack. I bet they control the output current, which I won't be needing. They contribute to the problem of finding a place for such a generic bms inside the wheel. How annoying. Edited June 28, 2021 by alcatraz Quote Link to comment Share on other sites More sharing options...
Planemo Posted June 28, 2021 Share Posted June 28, 2021 Unless I could find a BMS which communicates with any further BMS's to cut off all of them I would be wary, even if it had the upside of giving all string voltages. So for me the option would be one single BMS as you say but then thats a lot of strings to manage (or a lot of cells on each string...how many would you want max....?) Or use stock BMS's and simply tap into all the string outputs and make up some sorta Arduino thingy to then output it as Bluetooth data? 1 Quote Link to comment Share on other sites More sharing options...
Boris Lämpel Posted June 28, 2021 Share Posted June 28, 2021 9 hours ago, Chriull said: So if one only BMS cuts off the charging port it gets overcharged through the output by the other bms?! Has chris found a solution for this problem? I'd personally prefer having the possibility to watch/supervise single cell voltages than this "automatic overcharge cut off" - one just has to be aware of this and regularly check the batteries before and after charging. The charging port of the whole wheel will get cut off. How overcharging protection between the parallel cells works I do not know. Quote Link to comment Share on other sites More sharing options...
Chriull Posted June 28, 2021 Share Posted June 28, 2021 3 hours ago, Boris Lämpel said: The charging port of the whole wheel will get cut off. How overcharging protection between the parallel cells works I do not know. This can only happen if the bms hava a sync line... Imho Quote Link to comment Share on other sites More sharing options...
alcatraz Posted June 29, 2021 Author Share Posted June 29, 2021 Have any of you guys seen the sizes of these generic bms? Forget the "one bms per pack" structure. It's going to be one very good bms with solid balancing and rider communication. Connect as many packs as you want to this one bms. You'll need thicker balancing wires to provide ample current support between packs. Quote Link to comment Share on other sites More sharing options...
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