13s4p BMS connection sequence/steps

Just finished building a 13s4p 52V battery pack for an E-Bike. I opted for the YIT 48V 13s BMS COMMON PORT board.

My first step after the pack was assembled was to connect the BMS B- thick wire to the negative side of the battery pack, consisting of, 18650 Li-ion cells.
Next making sure the 14 lead cell monitoring connector was disconnected from the BMS board I started connecting the 14 wires to the pack.
Starting with the only black thin lead on the 14pin connector to the negative side of the battery pack.
Followed by the next wire, right next to the black thin wire, which was a thin red wire. This wire measured 4.19V.

Did this for the remaining 12 red thin wires till all of the thin red wires were connected.
Then with the negative lead of my voltmeter on the thin black wire on the connector and the positive lead of my voltmeter on the third pin I read 8.4V.
I checked all the pins on the balance connector confirming they were in increments of 4.2V I then plugged in the balance lead connector to the BMS seconds later smoke started coming from the BMS board.

Where did I go wrong?

You connected the balance leads to the BMS before connecting the battery Pos/Neg connectors? If so, this may be why it blew up.

Korishan said:

You connected the balance leads to the BMS before connecting the battery Pos/Neg connectors? If so, this may be why it blew up.

Click to expand...

No.

Nothing connected to the BMS

Removed the voltage monitoring cable assembly from the BMS board.

Connected the B- wire to the negative side of the 13s4p pack

Connected the thin black wire from the cable assembly to the negative of the 13s4p pack.

Connected each thin red wire starting with the one closest to the black thing wire.

Each thin red wire mentioned above was tested and the voltage walked up starting from 4.16V.

As in 4.xx then 8.xx etc.

But what is the order in how you connected the wires back to the bms?

* Absolute Pos/Neg first then the balance leads
* Absolute Neg first then balance leads, then absolute Pos
* Absolute Pos first then balance leads, then absolute Neg
* Balance leads then absolute Neg then Absolute Pos

What does the documentation say? It's possible you may need to connect absolute Neg, then with the balance connector connected, start working down the cells, then connect absolute Pos.

I can't tell from your post where you connected the thin red wires? You did connect them to the positive of each parallel bank? All the packs I've built I've never worried about sequence. Solder on the balance leads and plug into the BMS as last step.