The internal wiring diagram of Citycoco 72V battery packs is a standardized series-parallel connection scheme designed for 1500W high-power models, covering cell connection, BMS wiring, balance circuit, and power output circuit. The core wiring logic is based on 20 lithium battery cells connected in series to form a 72V high-voltage power supply system, with parallel cell groups appropriately matched according to capacity specifications to improve discharge stability. The entire wiring system is divided into two core parts: the main power circuit responsible for high-current discharge and the balance sampling circuit responsible for cell voltage monitoring, which together ensure the safe and stable operation of the 72V battery under 1500W high-load conditions.

The main power circuit wiring follows a strict series connection rule. According to the standard diagram, users need to arrange 20 single lithium cells in order, and connect the negative terminal of the previous cell to the positive terminal of the next cell through nickel strips and high-current wires to form a complete series loop. The positive terminal of the last cell is the total positive output of the battery pack, and the negative terminal of the first cell is the total negative output. For high-capacity versions such as 30Ah and 40Ah, two or three groups of series cell strings are connected in parallel on the basis of the series structure to increase capacity and discharge current. The main circuit adopts 12AWG high-temperature resistant copper wires to withstand the 30A+ instantaneous current of the 1500W motor, avoiding wire heating and aging.

The balance sampling circuit is a key auxiliary part of the internal wiring, which is directly connected to the BMS to realize real-time monitoring of single-cell voltage. The wiring diagram shows that each cell connection point corresponds to a balance sampling wire, which adopts 22-24AWG fine wires with low current load. The sampling wires are arranged in order from B- (the negative pole of the first cell) to B+ (the positive pole of the last cell), with one wire for each series node, feeding back the voltage data of each cell to the BMS in real time. When individual cells have voltage imbalance, the BMS will start the balance function to adjust the cell voltage difference, prevent partial overcharge or over-discharge, and extend the overall cycle life of the battery pack.

The final wiring assembly and safety standards are clearly specified in the diagram. After completing the main circuit and balance circuit wiring, all wiring joints need to be welded firmly and wrapped with insulating heat-shrinkable tubes to prevent short circuits caused by wire exposure. The BMS is fixed in the middle of the battery pack, with the power output interface and charging interface respectively connected to the main circuit’s positive and negative poles. All wires are arranged neatly and fixed with high-temperature adhesive tape to avoid wire loosening and friction damage caused by vehicle vibration during riding. After wiring is completed, a multimeter must be used to test the total voltage (standard 84V full voltage, 72V nominal voltage) and single-cell voltage to ensure no wrong wiring or virtual connection, so as to match the stable power supply demand of the 1500W motor.