12S lion BMS

[charlesb123]

I need some 12S bms boards for use with standard 6S RC battery packs. The 13S boards are much more common, is it possible to mod these boards for 12S use. I assume I can just remove the components on the pcb for the 13th input. It looks like each of the inputs switch the fet pack when it drops below the minimum cell voltage. I'm pretty sure the last 12S board was a 13S with parts missing, but it's all shrink wrapped up now. Does that sound right?

 

[fechter]

Most typical cheap BMS boards can easlily be used with fewer cells. More advanced ones will detect the missing cell and fault, but those are generally programmable.

In your example, the 13s BMS will likely have B+, B- and 14 balance wires going to it. Balance wires start at B- and go up to cell 13 (B+). Take the top two balance wires and connect them together so that will now be cell 12. No need to remove the parts as they won't be getting any power. Just make the unused ones at the top and join their balance wires together.

 

[charlesb123]

Thanks fechter, that's nice and simple!

 

[Telemachus]

Charlesb123,

Which 13S BMS are you looking to use?

I also have had a hard time finding any 12S BMS, so I have been thinking of just doing two sets of 6S charging leads to be hooked up to a hobby charger in parallel, and using a low voltage alarm to know when to stop using them.

 

[Telemachus]

Thanks fechter, that's nice and simple!

How far could this be taken, Fechter? Could a 36V BMS be taken all the way down to a 24V my bridging several connections?

 

[fechter]

How far could this be taken, Fechter? Could a 36V BMS be taken all the way down to a 24V my bridging several connections?

With a lot of them, you could take it down to 3s and it would still work. Just a lot of unused parts on the board. The ones with separate parts for each channel work like this. Ones with a big chip for several channels are different and probably won't work.

 

[spinningmagnets]

Thanks fechter! I was too embarrassed to ask anyone this, and my waiting has paid off with someone else bringing it up...

 

[Telemachus]

So possibly you could get a cheap hover board pack off ebay and use the BMS on it for 12S!

Just need a 50.4V charger...