Lithium batteries are used in a wide range of applications, from digital products, energy storage products, electric bicycles, electric scooters, electric vehicles to intelligent AGV, etc. Different products require different voltages and capacities, so lithium batteries are most assemble in series and parallel, lithium batteries through the installation of protective circuits, Shell, output and formed the application of batteries called Pack, Pack can be a single battery, such as digital camera batteries, Bluetooth device batteries, you can also combine batteries by series and parallel, such as electric bicycle batteries, electric motorcycle batteries, energy storage power supply, electric vehicle batteries, etc.
1.Pack Composition
Pack includes battery pack, protection board, outer packing or shell, output (including connector) , key switch, charge indication and Eva, highland barley paper, plastic bracket, etc..
The outer features of pack are determined by the application. There are a lot of different kinds of packs.
2.Battery Pack main component introduction
The battery pack is composed by single cell through series or parallel. Parallel increase capacity, voltage constant. Series increase voltage, capacity constant. For example, 72V 45Ah can be assembled by 3.6V 2500mah cylindrical battery cell in the mode of 18 parallel and 20 series.
The battery cell that can be series and parallel should have the same material, same model, the capacity, internal resistance, voltage difference should be less than 2%. In this way the battery charge and discharge curve is consistent. Normal, battery through series and parallel combination, the capacity loss will be 2%~5%. The more battery cell, the more capacity loss. But if the battery cell is the same batch and has similar chemical properties, it will improve the battery pack performance a lot.
3.Main Material List
| No. | Material Name | Application | Remark |
| 1 | Lithium battery Cell | Provide energy, the core accessory of the pack, when discharge, transfer chemical energy to electrical energy, when charge, transfer electrical energy to chemical energy. | Many different types, models |
| 2 | Protection Board/BMS | Protect the battery usage under safety environment, is the necessary accessory for the battery pack. May have Can Communication Function. | Based on customers equipment to equip. |
| 3 | Shell | The package carrier of the battery pack, protects the battery from external forces and looks aesthetic, easy to install in the battery application equipment. | Different Material, from Metal to Plastic. |
| 4 | Key Switch | Powe output switch, electric vehicle battery necessary accessory. | |
| 5 | Electricity indicator | Indicate the rest power of the battery. Show in the mode of voltage or integral calculation. | |
| 6 | Highland Barley Paper | Isolation and insulation, isolation battery from other components. | |
| 7 | EVA | Isolation and shock absorption, used for filling to fix the battery position. | |
| 8 | Bracket | To shape the battery, so that battery can be arranged in a certain order and convenient heat dissipation. | |
| 9 | High -temperature Tape | Isolation and insulation, Isolate the accessories that need to be isolated | |
| 10 | Nickel Strip | Completes the parallel and series connection of the battery pack | |
| 11 | Lead wire | Connect the battery output. | |
| 12 | Output Connector | Battery output connector ,realizes the matching connection with the use end | |
| 13 | Label | Display the battery pack parameters and precautions for use. | |
| 14 | PVC | Battery Packaging, heat shrinkable molding | |
| 15 | Switch to protection board | Battery positioning, series connection and parallel connection are realized | |
| 16 | Insurance Tube | Over-current protection, prevent abnormal high current damage equipment |
The battery pack should confirm to customers user requirements such as working time, environmental requirements, vibration requirement, charging requirement and cycle life requirement, Can Communication requirements, etc.
4.For the electric vehicle battery pack, to satisfy requirements, professional lithium battery manufacturers take the following measures.
1) Adopt top A level lithium battery cell. All our battery cell is Top A Electric Vehicle levels, have good battery consistency, low internal resistance, can support large current discharge. Before assembling the battery pack,100% single cell should pass a series of safety tests and performance tests, after approval, then can be well used.
2) Reasonable battery structure. The battery should withstand the road bumps, it have high requirements on the welding technology, the spot welding should be firm. Also, need good shock absorption protection.
3) Ventilation design. For battery, if discharge higher than 1C means the battery will have a 20°C temperature raise. When design, we consider heat dissipation, the distance between 2 adjacent single cell should be no less than 2mm. This structure requires plastic bracket to stationary battery.
4) Different batch battery cell to pack typical products and do the cycle life testing. Get the actual cycle life data through battery pack cycle life test.
5) 100% battery pack tested before delivery. Verify the battery high & low temperature performance.
SmartPropel Original Writer:Nancy