Did I screw up? BMS question.

[striider]

This is my first battery build and I think I screwed up. I want to build (3) 12 volt batteries to replace my RV house batteries. bought 12 304AH Eve cells from Docan in Houston as well as a

JBD Smart BMS 7~21S 8S 16S 20S 200A 300A​

from them. The wiring diagram shows wiring them all in a series, which I am not doing to get to 12 volts only. Can I connect the 0 wire (negative) and the B+ (positive) to just one of the cells and have the BMS still monitor all 12 cells? I think once the BMS senses 12 cells, it will look for a 40 volt battery? Sorry, not sure how these BMS's work yet.

Do I need 3 4s BMS's to complete this project instead? Is there another way to configure this?

Here is the diagram:

 

[42OhmsPA]

You need a 4s BMS to make 12v packs. The ones you have will not work and need swapped.
Why 12v?
Is it to late to order 4 more cells and make 2 24v batteries? They would work with the BMS's you have. Then, when you realize you want to move to 48v you can rewire the BMS and reconfigure your cells to make 1 48v battery.
You could also run a converter to get to 12v, depending how much current you'd be pulling.

 

[striider]

You need a 4s BMS to make 12v packs. The ones you have will not work and need swapped.
Why 12v?
Is it to late to order 4 more cells and make 2 24v batteries? They would work with the BMS's you have. Then, when you realize you want to move to 48v you can rewire the BMS and reconfigure your cells to make 1 48v battery.
You could also run a converter to get to 12v, depending how much current you'd be pulling.

12 volt for a plethora of reasons. 12 volt is what my 2008 RV is set up for, inverter/charger is 12 volt only, as well as my solar charge controller that is from 2008 and based on a 12 volt battery bank. Also, I would need a DC-DC converter to run all the 12 volt stuff in the RV.

I was afraid you would say that about the BMS(s)...guess this is a learning process.

 

[42OhmsPA]

I'd contact Docan and see if they will let you swap them out.