12v 4s 30a Lifepo4 BMS - Series Capable 12/24/36/48v

These BMS units were recovered from medical batteries. They are one of the highest quality 4s lifepo4 30a BMS units you will find. They can also handle 80 amps for up to 30 seconds.

Since they have upgraded mosfets they can be series connected up to 48v.

Fully charged - 14.6v
Fully discharged - 10v
Max continuous charge - 20a
Max continuous discharge - 30a
30 second pulse discharge - 80a
Dimensions - 6 5/8" x 2 3/4" x 7/8"

As you can see in the 3rd photo the B- connection which goes to the main negative is on the top left and the bottom left will be the C- which will be the new main negative for charge and discharge connections. This BMS is wired like a smart in-line fuse on the negative connection with 5 balance lead wires to sense voltage of each series. When voltage and amps are within range the BMS will allow current to flow between B- and C-. When there is an issue with voltage or amps the current will be cut off between B- and C-. The balance lead wires check voltage of each series of cells like you would if you were checking voltage with a volt meter. You will get 2 tinned copper plates that lay on top of the copper on the PCB board as shown in the 3rd photo. You can make your main B- and C- connections with nuts and bolts. Many customers use cables with ring terminals and just bolt them down.

Balance lead wires are included:

Black wire - goes to main negative of battery pack
Blue wire - goes to 1st series cell group positive
White wire - goes to 2nd series cell group positive
Yellow wire - goes to 3rd series cell group positive
Brown wire - goes to 4th series cell group positive (main positive)

This BMS also has an LED light which is a nice indicator.

• Short Green (0.5 second flash): Idle, OK
• Long Green (1 second flash): Charging or discharging, OK
• Yellow flash: Near low voltage (below 20%)
• Red flash: Low voltage
• No Light: BMS is off or voltage is below 6v