When we talk about lithium batteries, we must make a distinction:
- Lithium battery cell (cell): the most basic element that composes the battery pack and battery pack, generally the voltage that can be provided is between 3v-4v;
- Lithium battery pack (Batteries): a collection of multiple monomers to form a single physical module, providing higher voltage and capacity;
- Lithium battery pack (pack): It is generally composed of multiple battery packs. At the same time, a battery management system ( BMS ) is also added, which is the final product provided by the battery factory to the user. That is, we often say lithium batteries.
Today let’s talk about lithium battery storage packs.
What is an energy storage lithium battery pack?
Lithium battery pack generally refers to assembled batteries, mainly refers to the processing and assembly of lithium battery packs, to process cells, battery protection boards, battery connection sheets, label paper, etc. into products required by customers through the battery pack process. Lithium battery packs are now mainly concentrated in lithium battery pack factories. They all have their PACK structure design, PACK electronic design, and PACK production workshop. They can independently develop and design according to customer needs. Through battery solutions, and battery specifications, After the battery samples meet the customer’s PACK lithium battery customization requirements, the PACK production line in the PACK workshop will be processed, and the products will be shipped after passing the quality inspection.
Composition of the energy storage lithium battery pack
Energy storage lithium battery pack includes a battery pack, bus bar, flexible connection, protective plate, outer packaging, output (including connector), highland barley paper, plastic bracket, and other auxiliary materials to form PACK.
The production process of energy storage lithium battery pack
Main process standard of energy storage lithium battery pack
In the lithium battery pack industry, people call the battery that is not assembled and can be used directly as a battery cell, and the finished battery pack that is connected to the PCM board and has the function of charging and discharging is called the lithium battery pack.
The lithium battery PACK process refers to the assembly of battery cells, protection plates, battery wires, battery nickel sheets, battery accessories, battery boxes, battery films, etc. into finished batteries by welding. The battery pack PACK requires the battery to have a high degree of consistency (capacity, internal resistance, voltage, discharge curve, and life).
Most of the existing lithium battery PACK technology is to link the cells together by welding, which also complicates the maintenance of battery problems. In addition, batteries may face many difficult problems when they are packaged in batches. To ensure batch products’ Reliability, an excellent battery PACK process, and finished product testing are essential.
Cell appearance full inspection standard
Cylindrical cells: no short circuit, oxidation, and rust, leakage of the surface pad or skew of the surface pad, membrane rupture, membrane wrinkle, etc.
Square cells: no electrolytes, burrs, or other contaminants on the surface, no leakage, bulging, deformation, short circuit, etc., no skew and warping of the surface pad, no oxidation, dirt, desoldering, etc.
Appearance standard of polymer batteries: no electrolyte or other contamination on the surface, no leakage, air swelling, deformation, etc., no breakage of the tab, no damage to the corner, no delamination of the folded edge, etc.
Standard of battery veneer pad
The surface pad is required to be firmly pasted, not skewed, warped, not beyond the edge of the cell end face, and not covered with the negative rivet—aluminum shell cell positive cap (when there are many parallel series, the formed highland barley paper or red steel paper is used to paste) — -For steel shell cylindrical cells; wrap with textured paper or high-temperature adhesive tape—polymer cells.
Cell voltage and internal resistance test
Test equipment: multimeter, multi-function test stand, battery internal resistance tester, general battery test stand, barcode scanner.
Test connection method: The positive and negative terminals of the cell are respectively contacted and tested with the positive and negative thimbles of the test frame.
Cell combination standard
Cylindrical battery: Glue sticking process, multi-parallel series use glue to stick 2 or more battery cells together.
Polymer battery: use transparent glue to wrap around a week and a half and paste the combination.
Soldering Standard
Soldering time ≤3S; Soldering temperature: 320~360 ℃; Protection board soldering leads and plugs: Solder leads and plugs that meet the requirements on the corresponding pads of the protection board according to the welding direction required by the process.
Requirements and self-inspection: The tin point completely covers the tin head of the lead; there is no virtual soldering, desoldering, tin connection, tin slag, tin tip, component falling off, lead scalding, scalding, plug terminal falling off, etc.
Spot welding standard
Protection plate and the nickel strip: The premise is that the pad of the protection plate must be affixed with a nickel-plated steel sheet to be connected with the nickel strip by spot welding.
Requirements and self-inspection: The solder joints are firm, and there is no explosion, desoldering, fracture of the nickel strip, point deviation or point to the components around the pad, and the direction of the nickel strip must meet the process requirements or be consistent with the sample.
PVC film heat shrink standard
It is required that the heat shrink is flat, without wrinkles, broken membranes, or bevels, and no battery cores, protective plates or plugs, lead wire cores, etc. are exposed.
The standard for battery plastic case and plastic frame
Usually, all plastic shells and plastic frames will have positioning grooves, positioning posts, or card positions of the protective plate. When the battery is put into the shell or frame, according to the process requirements, first paste double-sided tape or punch on the contact surface between the battery and the shell and frame. Silica gel, etc., and then snap the protective plate on the battery to the positioning groove, positioning column, or card position, and finally put the battery body into the plastic shell and plastic frame. If there is an upper shell, the upper shell needs to be closed.
Sunket has our PACK structure design, PACK electronic design, and PACK production workshop, which can independently develop and design according to customers’ requirements. After the battery plan, battery specifications, and battery samples meet customers’ customized requirements for PACK lithium batteries, the PACK production line of the PACK workshop will carry out production and processing. The goods will be shipped after a qualified quality inspection.
Energy storage lithium battery pack quality control
- Using high-quality lithium batteries.
- It is required that the lithium battery has low internal resistance and good consistency. Low internal resistance ensures the capacity, platform, and heat dissipation of high current discharge.
- The battery structure adopts a ventilation design, and the distance between two adjacent batteries is not less than 2mm. This structure requires the battery to be fixed with a plastic bracket.
- A slotted nickel sheet is used for spot welding. The size of the nickel sheet meets the requirements of high current discharge. The nickel sheet material ensures low internal resistance.
- In the selection of nickel sheets and copper bars, the current of the wiring harness is 5A per square millimeter, and the selection of copper bars is conservative, 3-4A.
Features of the energy storage lithium battery pack
- There are complete functions, which can be directly applied; the diversity of types and the same application requirements can be realized by a variety of PACKs.
- The lithium battery pack PACK requires the battery to have a high degree of consistency (capacity, internal resistance, voltage, discharge curve, and life).
- The cycle life of a lithium battery pack PACK is lower than that of a single cell.
- Use under limited conditions (including charging, discharging current, charging method, temperature, humidity conditions, vibration, stress, etc.)
- The lithium battery pack PACK protection board requires a charge equalization function.
- High-voltage, high-current battery packs (such as electric vehicle batteries, and energy storage systems) require communication buses such as battery management systems (BMS), CAN, and RS485.
- Lithium battery packs have higher requirements for chargers, and some require communication with BMS. The purpose is to make each battery work normally, fully utilize the energy stored in the battery, and ensure safe and reliable use.
Sunket as a comprehensive strength strong lithium battery manufacturer can provide customers with batteries + BMS + structure design of customized services, from the demand of batteries attribute of production and manufacturing, to design and manufacture of appropriate application of BMS, and then the structure design of the battery PACK at the end of the battery PACK is completely independent, Guarantee the battery quality so that customers rest assured to use.