JK BMS missing cell info on status page

[philos70]

I hooked up my 16s battery today and one of the lines is not reporting cell voltage. I get an error message saying cell count is not equal to settings. The cell itself reads 3.58 volts, so the cell is good. Anyone have an idea what is going on with the BMS?

 

[GXMnow]

First thing is unplug the balance harness from the BMS and measure each cell voltage at the BMS plug end. I think you have a BMS wire out of sequence. That would give a negative voltage between 2 pins the BMS will not show that.

 

[HRTKD]

If the above post isn't the problem, use your multimeter to check the continuity of that balance lead from the ribbon connector to the end of the lead. (Do disconnect everything first)

You have a significant difference in cell voltages. Did you top balance the cells first?

 

[philos70]

I'll try the above. Will report back...

 

[philos70]

I unplugged the balance harness from the BMS. I measured the voltage for cell #9 between the cell negative and BMS side of the harness pin c9+. It was 3.42 I did the same in reverse for C9- on the harness, and the positive pole on Cell #9. 3.42 volts.

I had a second BMS and switched out the BMS. Everything is the same. Cell #9 continues not to show up.

I then switched out the red and black balance harnesses/connectors from the second BMS. Cell #9 is still a no show on the app.

I put a multimeter between the negative pole on cell #9 and the positive on the red balance lead connector on the rail and got 3.42 volts. I put the multimeter tween the positive pole on cell #9 and negative on the on the rail connector and got 3.42 volts. When I put the multimeter between the C9- and C9+ on the connecter on the rail I got no volts. (first pic)

When I bypass the BMS and measure voltage at the 16s battery poles, it's 54.7. When I measure at the poles on the outside of the battery box the voltage is 51.3.

I'm on a steep learning curve here. The above makes me think it's a user error somewhere in how I wired the cells. Any help offered is much appreciated.

Time to go brew some beer.

 

[HRTKD]

The only thing I can think of is that somewhere in the C9- or C9+ wires something is goofy. You changed out the BMS so that pretty much rules out the BMS. I would swap out the cables from the old BMS to the cables from the new BMS. If that still doesn't work then change out the rail.

Is it possible that cell #9 has been turned off in the BMS parameters? Once again, you swapped BMS so I doubt you accidentally disabled cell #9 in both of them.

Off topic but your the end of your NTC lead should be on the top of the cell, not sitting in the gap between the cells columns.

 

[GXMnow]

I found a PDF manual for the JK inverter BMS

https://srikobatteries.com/wp-content/uploads/2023/11/JK-Inverter-BMS-Manual-1.pdf?srsltid=AfmBOoo8PmydRWqK-KrNjFxVIVfQE-ORRi2pJS6BGCl3TmZZa7FfAbRO

Page 17 shows the connections. It looks to me like the BMS in your picture is turned around the other way. I can see B12 between the two connectors with black wires. Your group of red wires shows C12+ on the upper PC board. That's not good. I think you may have the red and black harnesses flipped. The huge voltage difference across those may have done some damage.

At the BMS board, the 3rd pin from the right should be the pack negative, Cell 1- but following the wires in your pictures, it is going to cell 9-. That is applying over 25 volts to the 0 volt point on the board. I would not be surprised if it has burned a lead off the PC board.

 

[rhino]

I think you may have the red and black harnesses flipped.

This. Good eye and research @GXMnow! I also had mine reversed even when using the regular JK Inverter BMS harness wires but caught it before I connected anything.

 

[philos70]

The only thing I can think of is that somewhere in the C9- or C9+ wires something is goofy. You changed out the BMS so that pretty much rules out the BMS. I would swap out the cables from the old BMS to the cables from the new BMS. If that still doesn't work then change out the rail.

Is it possible that cell #9 has been turned off in the BMS parameters? Once again, you swapped BMS so I doubt you accidentally disabled cell #9 in both of them.

Off topic but your the end of your NTC lead should be on the top of the cell, not sitting in the gap between the cells columns.

I haven't gotten that far. Once the BMS works I'll deal with that.

 

[philos70]

I found a PDF manual for the JK inverter BMS

https://srikobatteries.com/wp-content/uploads/2023/11/JK-Inverter-BMS-Manual-1.pdf?srsltid=AfmBOoo8PmydRWqK-KrNjFxVIVfQE-ORRi2pJS6BGCl3TmZZa7FfAbRO

Page 17 shows the connections. It looks to me like the BMS in your picture is turned around the other way. I can see B12 between the two connectors with black wires. Your group of red wires shows C12+ on the upper PC board. That's not good. I think you may have the red and black harnesses flipped. The huge voltage difference across those may have done some damage.

At the BMS board, the 3rd pin from the right should be the pack negative, Cell 1- but following the wires in your pictures, it is going to cell 9-. That is applying over 25 volts to the 0 volt point on the board. I would not be surprised if it has burned a lead off the PC board.

I found a PDF manual for the JK inverter BMS

https://srikobatteries.com/wp-conte...dRWqK-KrNjFxVIVfQE-ORRi2pJS6BGCl3TmZZa7FfAbRO

Page 17 shows the connections. It looks to me like the BMS in your picture is turned around the other way. I can see B12 between the two connectors with black wires. Your group of red wires shows C12+ on the upper PC board. That's not good. I think you may have the red and black harnesses flipped. The huge voltage difference across those may have done some damage.

At the BMS board, the 3rd pin from the right should be the pack negative, Cell 1- but following the wires in your pictures, it is going to cell 9-. That is applying over 25 volts to the 0 volt point on the board. I would not be surprised if it has burned a lead off the PC board.

the harnesses were reversed - TOTAL USER ERROR. I love learning, and making a fool of myself in public...

 

[GXMnow]

Is it all working now? Or did it damage anything?

 

[philos70]

Is it all working now? Or did it damage anything?

It's all working. My tail is all aquiver!!! Thanks for all the help... This forum is great!!

 

[GXMnow]

It's all working. My tail is all aquiver!!! Thanks for all the help... This forum is great!!

Glad to hear it. The JK-BMS is a well designed piece. I am using one of their older black ones, been working for almost 5 years now. Only issue I had was a balance lead failed. It showed 2 cell as zero volts. Fixed the lead and it has been perfect again.

 

[philos70]

Glad to hear it. The JK-BMS is a well designed piece. I am using one of their older black ones, been working for almost 5 years now. Only issue I had was a balance lead failed. It showed 2 cell as zero volts. Fixed the lead and it has been perfect again.

What got me was the way the rails were arranged in the box I got. In my ignorance, rather than checking the embossed numbers on the BMS and box rail, I just hooked up the harness right rail to right BMS slots, etc. It never occurred to me that the way the rails were arranged in the box would require crossing the two harnesses. Lesson learned.