How to assemble 48V battery pack for 18650 lithium battery ( 18650 battery pack Assembly Plant )? In fact, the lithium battery has no voltage stabilizing function. It can only be understood as a reservoir. The voltage represents the water level. The water level has a certain range of variation and is not a fixed value. The nominal voltage of the 18650 unit is 3.7 volts. The maximum voltage cannot exceed 4.2 volts, and the minimum voltage cannot be lower than 2.5 volts. In fact, the minimum discharge is generally controlled at about 3 volts. To test single cell physical voltage and current, 5V 6A 8 Channel Battery Tester can be used. More channels with 256 or 512. Contact us for more details!

Of course, this voltage range is not really fixed at 48V, but approximate. The minimum discharge voltage is 2.75 * 13=35.75V, while the maximum charging voltage is 4.2 * 13=54.6V.

Although a simple series connection  can increase the voltage like a stack of arhats, the lithium battery is too delicate and dangerous. It cannot be over discharged or  overcharged. That is, the charging voltage cannot be too high, otherwise it may explode, and the battery cannot be discharged  regardless of cost, otherwise the battery will be damaged. Therefore, a thing is needed to protect the overcharge or overcharge, which is the lithium battery protection plate. There are already mature ready-made protection boards on the market. It is good to buy them directly  and use them according to their drawings and the requirements of the instructions. Just don't connect them incorrectly. In order to test  whether  the  protective  board  is available , the  protecting  board tester  is  also  indispensable ,  it  is  also called  Protective Plate BMS tester PCB Tester. TMAX Equipments can provide 24 Series BMS tester Up to 120A or 150A (Overcurrent) Lithium Battery BMS Testing Machine. 32 series BMS tester Up to 150A/200A/300A (Overcurrent) with computer and cabinet.

Generally, the internal resistance of the 18650 single lithium battery is about 70 milliohms. If there are too many batteries in series, the internal resistance will certainly increase with the series connection, while the parallel connection is just the opposite. The greater the internal resistance, the more heat, the lower the efficiency, and the higher the temperature. If the temperature is higher than a certain value, the lithium battery will be damaged.

The connection of lithium battery is also a problem, because the battery shell is steel, and the ordinary electric soldering iron is not good for welding. It often requires the use of a special spot welder. If the welding is not good, the internal resistance of the battery pack will be increased, and it is easy to cause heat in frequent charging and discharging, which may cause unexpected safety accidents.

The connection copper wire and copper strip between batteries are also important. The selection should be calculated according to the current. Of course, the thicker the copper wire is, the better. It can also reduce the internal resistance between battery packs.

TMAX can offer a full solution for Lifepo4 Battery Pack Assembly Line, please feel free to consult us!