Battery and BMS are not wired properly?

Have a lifep04 pouch battery made of 24 cells for my cargo bike I bought used off the forum a while back. 12s2p
Charger died and so I wanted to learn about the inner workings of this beast and I took the cover off.
Appears that the BMS is not wired right? I am learning about this and I also want to add a cell logger to put on here so I can see the actual voltages. Shouldnt the first small sense wire b- be on the negative of the battery, then the first b+ be on the + of the first cell, then repeat b2, b3, etc. all the way up to b11, then the last b+ on the final + battery output?
Seems like whomever wired this didnt put the sense wires on the BMS properly? Never worked on a battery like this before so any help is appreciated.

It's difficult to tell what's going on from the photos.

The B- goes to the negative end of the pack.

The first positive sense wire, which is next to the B- one on the connector on the BMS, goes to the positive side of the cell you attached the B- to.

Usually the sense wires only go on the positive ends of the cells.

So the main B- is at the most negative end of the pack, and then the sense wires start at the positive end of that cell, and each positive after that.

The top cell may not have a sense wire, because the BMS may read it from the main B+.

Sorry the photos arent good.
Thnks for taking mercy on me and replying.
I'm going to go ahead and rewire this the way I think it should be done. Worst case scenario I blow up the BMS.
I want a bluetooth one anyway. Haha

I doubt any if many readers can tell from your pics whether it is right or wrong. I'm not sure if your sense connector contains 11 wires or 12 wires. If people knew that, then they could help you out better, but they did tell you how an arbitrary BMS is hooked up. Good luck!

Mikebike said:

I'm going to go ahead and rewire this the way I think it should be done. Worst case scenario I blow up the BMS.

Click to expand...

If it is working, why would you do that?

This battery is old and I have new cells on the way.
This essentially is a test bed for me to understand how to work with a battery and the BMS so I feel comfortable building my first new battery. If something happens to this battery I'm not stressing it-as it is about done.
The comments above it reinforce my belief that this BMS is not wired correctly (there is no b- wire to the first negative of the battery, there are no b+'s to the next iterative pluses on the rest of the cells either). So it's wrong from the get go, even if somehow it did work without going all puffy on me. Wether the wrong sense wiring configuration contributed to the death of the charger, I do not know.

Also, I like your signature line,
"If it aint broke, improve it till it is" haha!!

Mikebike said:

(there is no b- wire to the first negative of the battery,

Click to expand...

Then where does the pack main negative come from?

There has to be a main B- (battery negative, regardless of what htey call it) wire, or else you can't get power out of the pack.

there are no b+'s to the next iterative pluses on the rest of the cells either

Click to expand...

There won't be. There'd only be a single B+ at the very most postiive end cell of the pack (which may or may not also have a sense wire).



As for charger death...most of them are pretty crappy, and what usually happens is either:

--fans die or stop moving enough air, and stuff inside overheats. Can be a dramatic failure, or just slowly degrade.

--capacitors age and fail internally (especially when hot); you sometimes see them swell up or even "explode", sometimes no visible problem. This can lead to other parts dying that depended on the caps.

--vibration cracks and breaks off parts, either breaking the PCB or just the solder, sometimes cracks the leads to the parts right at teh case entrance or the PCB.

--wires break from bending back and forth, usually at the exit from the charger, or entrance to the plug at the battery end. Sometimes inside the plug itself, pulling out from the contacts.

Other stuff too, but those are the main ones.

OK, so I pulled all the sense wires off the battery and started to rewire it.
Interestingly, I tested the BMS with a multimeter and found the B- was already coming from the negative of the battery and so no b- for the sense wires needed. Ran 11 sense wires to the pluses for each cell and then back to the BMS. Tested with the multimeter and showed OK on the voltages as I worked my way up from the first b1+ on the connector. That left me with last b+ and this was already hot from B+/P+ so all seems good at this point with no smoking or heat coming from the BMS or the battery.
Now I need to get a connector to go from the Anderson to XT60 to the new hobby charger I just bought. Have to read the instructions on the hobby charger also.
Going to try to charge this battery tonight. Cells are currently sitting at about 3.3Volts. This is a lifepo4 battery and I figure I should charge it up to 3.6 (12*3.6 would be 43.3 volts).