Battery Technical Info, Industry News

Lithium Battery Pack Process Knowledge & Material List


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 NameApplicationRemark
1Lithium battery CellProvide 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
2Protection Board/BMSProtect 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.
3ShellThe 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.
4Key SwitchPowe output switch, electric vehicle battery necessary accessory. 
5Electricity indicatorIndicate the rest power of the battery. Show in the mode of voltage or integral calculation. 
6Highland Barley PaperIsolation and insulation, isolation battery from other components. 
7EVAIsolation and shock absorption, used for filling to fix the battery position. 
8BracketTo shape the battery, so that battery can be arranged in a certain order and convenient heat dissipation. 
9High -temperature TapeIsolation and insulation, Isolate the accessories that need to be isolated 
10Nickel StripCompletes the parallel and series connection of the battery pack 
11Lead wireConnect the battery output. 
12Output ConnectorBattery output connector ,realizes the matching connection with the use end 
13LabelDisplay the battery pack parameters and precautions for use. 
14PVCBattery Packaging, heat shrinkable molding 
15Switch to protection boardBattery positioning, series connection and parallel connection are realized 
16Insurance TubeOver-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