BMS Modification Question RJXZS

Anyone ever modify BMS's
I have acquired 8 12s BMS's
They are RJXZS Brand. I am hoping they can be modified.
The circuit board actually says 15s, but some of the battery leads have been jumpered to make it 12s. I'm wondering if i could just unsolder the jumpers.. All the circuitry looks to be present for 15s. I do know that some BMS's that they are good for UP to so many cells, and you can use less. just tie some leads together.. I'm Hoping that someone might have some insight.

Does the layout of the jumpering resemble something like either of the pictures below?






I have both some JBD BMSs and JK Active Balancers, which can go up to 24s, but to do something like 16s for example, they do jumpering of some of the leads near the end of the string like what you're describling in your post, except it sounds like you're saying your leads are jumpered on the board-traces or something?

No, it's just 1 balance connector. not 2 parts. I'm learning that this is a JBD-sp15s020 board.. I just gotta find the selectable options for it..
been looking for a while now..Hopefully i find out some info soon.

Dacflyer said:

No, it's just 1 balance connector. not 2 parts. I'm learning that this is a JBD-sp15s020 board.. I just gotta find the selectable options for it..
been looking for a while now..Hopefully i find out some info soon.

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Would you mind taking some pictures showing those jumpers and the harness pigtail?

Heres a few pictures
The jumpers you see correspond to missing wires on the balance cable.. I can add in wires, but need to know which spots to remove the solder.
The board is a 15s, but set up as 12s currently.

Dacflyer said:

Heres a few pictures
The jumpers you see correspond to missing wires on the balance cable.. I can add in wires, but need to know which spots to remove the solder.
The board is a 15s, but set up as 12s currently.

Click to expand...

I'd say if it were mine? What have I got to lose by trying? (I guess whatever I spent on them at worse case), and perhaps if it didn't work then could undo the mod, test them, and sell them or something? Looks like a simple mod to desoldier...

Do you also have to add more wires to the harness pigtail / connector I assume?

Are they managed BMSs? Like can you go into the app and see if it shows all the blank cells in there? Or if they blocked them out in firmware or something?

I know on my JK Active Balancers (built for 9-24s flexibility), in the app over bluetooth connection, it would show all cells still there (until you changed the cell count down to 16s in the app (setting), and then it would only show 16 cells there (with voltages) for me.

When it would still be set at 24s in the app, a bunch of the cells (the ones jumped), would just show duplicate voltage, same like however the cells jumped together were wired physically.

Samsonite801 said:

I'd say if it were mine? What have I got to lose by trying? (I guess whatever I spent on them at worse case), and perhaps if it didn't work then could undo the mod, test them, and sell them or something? Looks like a simple mod to desoldier...

Click to expand...

I think finally I got the info i need.. I'll try it this weekend.

Samsonite801 said:

Do you also have to add more wires to the harness pigtail / connector I assume?

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Yes, but that won't be an issue

Samsonite801 said:

Yes, but that won't be an issue

Are they managed BMSs? Like can you go into the app and see if it shows all the blank cells in there? Or if they blocked them out in firmware or something?

Click to expand...

I'm not sure on that, as i have not powered them up yet. I still need to download the app as well.

Samsonite801 said:

I know on my JK Active Balancers (built for 9-24s flexibility), in the app over bluetooth connection, it would show all cells still there (until you changed the cell count down to 16s in the app (setting), and then it would only show 16 cells there (with voltages) for me.

Click to expand...

Yes, I have those as well.. 6 are in use on my other BMW battery Bank

Samsonite801 said:

When it would still be set at 24s in the app, a bunch of the cells (the ones jumped), would just show duplicate voltage, same like however the cells jumped together were wired physically.

Click to expand...

Gotchya.... Stay tuned, I'll let y'all know..