I am currently building my own battery pack, a12S 4P using 18650 cells from laptop battery packs. I can’t find a 12S BMS. Could I use 3S & 4S BMS in serie and/or in parallel to balance charge my 12S battery pack?
That would probably not work and even if it did it would be ver very complicated. @thisguyhere may have some charge only ones but u would have to ask him
i mean, that’s technically possible but why.
i’m out of 12s bms but you could easily source on supower, ebay, etc.
takes a while to deliver so plan ahead…
Yeah, actually, this is why I’d rather not buy a 12S BMS that would take weeks to be shipped.
Seems like a pain to do it haha
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Aliexpress has plenty if them
Yeah but I would like my BMS to be delivered in less than 6 weeks ^^"
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Pay for the shipping then I ordered a smart bms from AliExpress and it was in Canada in like 10 days.
Thank you for the idea. Paying for a better shipping sadly rarely pay off. I’d have to pay 15€ extra to see the shipping delay goind from “14-17 days” to “7-15 days”. Still not good for me.
Why don’t you just run your pack without a bms in the meantime? I highly doubt you’ll find a 12s BMS that you can get shipped to you in under a week. Either way I think your gonna have to end up waiting here or paying out the ass to try and get it asap.
Shoulda planned your build a bit more 
it happens to all of us I’m just waiting on Damn nickel to build my batteries and it was the first item I ordered for my builds 
Yep, I totally agree, I should have planned ahead ^^"
Runnng without BMS is a good idea, though. Thanks