Li-ion Cell Battery Pack Production: Assembly Line Equipment for Battery Processing

Introduction

The process of assembling lithium battery cells into a group is called pack, which can be a single battery or a series parallel battery module.

Pack consists of battery pack, bus bar, soft connection, protection board, outer package, output (including connector), highland barley paper, plastic cell holder and other auxiliary materials.

Features of Pack

1. Pack of battery pack requires high consistency of battery (capacity, internal resistance, voltage, discharge curve, life).

2. The cycle life of battery pack is lower than that of single battery.

3. Using under limited conditions (including charging, discharging current, charging mode, temperature, etc.).

4. The voltage and capacity of lithium battery pack have been greatly improved after forming, so it must be protected and monitored for charge balance, temperature, voltage and overcurrent.

5. The battery pack must meet the voltage and capacity requirements required by the design.

Pack Method

1. Series Parallel Composition

The battery is composed of single battery through parallel series connection.

When the capacity is increased in parallel, the voltage does not change.

After the series connection, the voltage multiplies and the capacity does not change.

For example, 3.6v/10ah battery is composed of a single N18650 / 2Ah through 5.

Parallel before series: due to the difference of internal resistance and uneven heat dissipation, parallel will affect the cycle life of battery.

However, the failure of a single battery automatically exits, in addition to capacity reduction, which does not affect the use of parallel, parallel technology is relatively strict.

When a unit battery in parallel is short circuited, the current of parallel circuit is very large, which is usually avoided by fuse protection technology.

Series Before Parallel

According to the capacity of the whole battery, series connection is carried out first, for example, the capacity of the whole battery is 1 / 3, and then parallel connection is carried out to reduce the failure probability of large capacity battery.

2. Requirements for Electric Core

Select corresponding electric core according to the design requirements.

The parallel and series batteries shall have the same type and model, and the difference in capacity, internal resistance and voltage value shall not be greater than 2%.

In general, the capacity loss of the battery is 2% - 5% when it is combined in series and parallel.

The more the number of batteries, the more the capacity loss.

No matter it is a soft packed battery or a cylindrical battery, it needs to be combined in multiple strings. If the consistency is poor, the battery capacity will be affected.

The battery with the lowest capacity in a group determines the capacity of the whole group of batteries.

High current discharge performance is required.

The starting current of the motor is three times of the normal working current, and the power performance of the motor can be improved only when the large current is discharged.

Good heat dissipation of battery is required.

The number of batteries is large, and the temperature rise of the batteries inside the battery box is not easy to disperse, resulting in uneven temperature and different discharge characteristics among the batteries, resulting in long-term degradation of battery performance. High level of production technology.

Others

1. Cylindrical battery pack assembly line machine is suitable for all kinds of cylindrical battery pack makingaccording to customer's requirement.

2. Machine can be chosen according to customer's cell  productivity.

3. Economic and high-efficiency.

Battery Cell, Module and Pack, What's the Diffenence?

Detailed Flowchart for Lithium Battery Pack Assembling

Detailed Steps to be Followed in Making Battery Pack

1. Cell Testing

Testing is done to establish the cell parameters i.e. voltage, capacity, cycle life ect.

2. BMS Testing

This Step checks whether the battery protection circuit functional indicators fall within the paramenter range.

3. Pasting Insulating Paper on the Positive Pole

Small insulating paper is pasted on the poles of cells to prevent a short circuit.

4. Battery Sorting

Batteryies are sorted according to their voltage and internal resistance.

The same voltage and internal resistance value battery are kept togather , so that consistency  and stability of the whole battery pack is assured during its life.

5. Putting the Cells in Brackets and Moulds

Cells are given a supporting structure to weld the together.

Nickel strips are also placed in the moulds to weld cells together.

6. CCD Testing

Before welding the cells, CCD testing is done to ensure that the positive and negative poles of the battery are above and below to prevent short circuiting.

7. Welding Cells

Welding of multiple cells provides a higher capacity battery.

A company uses any one of the welding techniques--spot welding, laser welding ect.

8. Pasting Insulation Paper and Pre-treatment of Battery Poles

Insulating paper is pasted on the battery pack to prevent the aging of PVC and so that chances of short circuit are reduced.

Pre-treatment of the battery poles is required to weld BMS easily.

9. Connecting BMS

Battery Management System is connected to the battery pack, so that it can be operated in the desired range.

10. Battery Pack Testing

A finished battery pack is tested to determine the charge and discharge voltage, charge and discharge current and total internal resistance.

11. Battery Pack Aging Test

A battery pack is charged and discharged several times and its capacity is recorded at each charge and discharge to detect the battery charge protection and discharge protection.

Main Stations