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Running into an issue with my first 16s battery pack (jkBMS)

ImAnIdiotPleaseBePatient

Solar Enthusiast
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Dec 10, 2022
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So I connected the batteries with the busbars.
Then I connected the ring terminals to the JK bms leads, and attached them as follows
--On the 15 pin connector, black to the main battery negative, and 1-14 to battery positives on cell 1-14.
--On the 11 pin connector, lead-1 to positive of cell 15, and the last lead to the main positive

Next, before plugging any of the plugs into the BMS or connecting BMS to battery negative, I took my multimeter and checked voltage differential on the back of the 15 and 11 pin connectors. First, checked black wire to red1, black to red2, etc etc. I saw...
black to red1 = ~3.2
black to red2 = ~6.4
etc, all the way up to ~52v from black wire to the lead connected to the main battery positive.

Having seen this in Youtube vids, I felt pretty confident to connect the BMS to the main battery negative, and plug in the 15 and the 11 pin connector to the JK.

Next, I turned it on, and connected to the app via bluetooth. The BMS only shows cell 1-15. Any ideas? It appears I am missing a cell, but the back of the 11 and 15 pin connectors all showed jumps of 3.2v, so I can't figure out why a cell would be showing as missing from the BMS app.

On the positive side, voltages across the "15" cells were identical, not that it matters too much because I know the voltage curve is flat here. Also should note that the JK is showing the pack voltage as ~48-49v, instead of the 52v of the pack
 
I measured here between black and red wires, and each one showed a ~3.2 increase in volts, all the way up to 52v total pack voltage before turning on BMS
 

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Does the highest voltage battery have two bms leads on it?

Top right battery (lowest voltage battery) should have two leads too.
 
Does the highest voltage battery have two bms leads on it?

Top right battery (lowest voltage battery) should have two leads too.
Cell 1 has black on the negative, and red on positive.

I figured out that lead2 from the 11 pin wiring harness goes to cell 16 main positive along with lead11 on the 11pin wiring harness from looking at some other wiring diagrams.

I hooked it up, fired up the BMS... Now cell 5 and 6 are missing, but cell 16 appeared 😂
 
Basically:

-first wiring harness (15 wire): black wire to main negative, 1-14 red wires to cell positive on cells 1-14

-smaller harness (11 wire): lead one to cell 15 positive, lead 2 to cell 16 positive, lead 11 to cell 16 positive
 
The black balance lead goes to the most negative cell(#One). Each corresponding number red balance lead goes to the positive of every sequential cell. The last cell positive should have lead 16 plus the very last lead in the harness
Basically:

-first wiring harness (15 wire): black wire to main negative, 1-14 red wires to cell positive on cells 1-14

-smaller harness (11 wire): lead one to cell 15 positive, lead 2 to cell 16 positive, lead 11 to cell 16 positive
Stop!
 
The black balance lead goes to the most negative cell(#One). Each corresponding number red balance lead goes to the positive of every sequential cell. The last cell positive
Stop!
The issue I run into is that the JK has 21 red wires and I only have 16 positives, so I am trying to figure out what to do on cell 15 and 16. do I just not use the last wires, but use wire 15 and 16 for cell 15 and 16?

I swear every JK wiring diagram shows something different for a 16s config.
 
The black balance lead goes to the most negative cell(#One). Each corresponding number red balance lead goes to the positive of every sequential cell. The last cell positive should have lead 16 plus the very last lead in the harness

Re read. this is how I have it hooked up. "very last lead in the harness" is what I meant by lead 11. It's an 11 lead wiring harness. So on cell 16 positive, I have red wire 16 and the "very last lead in the harness"

Sorry I am not good at writing this down yet.
 
The wires between the two I plucked are not used. Those two (B+ and 16) are joined at the terminal + 16
IMG_1459.jpeg
 
Ok, so it turns out it was wired ok after the first fix that I couldn't communicate well, I just don't crimp terminals very well. I wasn't crimping until the tool automatically released. I just squeezed what I thought was hard 😣

Every time I fixed a "missing cell" another two seemed to pop up. Going to have to redo all of them more than likely.
 
I think until you have it figured out you should unplug the balance leads
I know, I keep unplugging them to play with it, but the only way to see if they showed up in the app when I thought it was fixed was to plug them back in... check... and then realize I didnt fix it and unplug them again 😂
 
I’ve become OCD about those things.
For some reason that small wire and insulated terminal suck for crimping. I use un insulated, fold in die and a dab of 60/40 solder before heat shrinking. The solder is primarily there to plug the end from moisture. Never ever will that end loose contact again lol.

IMG_0824.jpegIMG_0564.pngIMG_0100.jpeg
 
Battery is currently charging up at 5 amps while the JK top balances the cells, and the mower is powering up aok! Thanks everyone, much appreciated. Now I have to clean up the wiring and make sure everything is tightened and torqued up.
 
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