The battery pack generally refers to packing and assembly, and the battery pack generally refers to the assembled battery. The lipo rechargeable battery is a single-cell lithium battery connected in series and parallel to form a certain voltage and capacity, and the protection board is installed, which can be charged and discharged. For example, when two batteries are connected in series to form a specific shape according to the customer's request, we call it PACK.
The PACK battery assembly technology is a critical step in the production of lithium battery packs, and its importance is becoming more apparent as the electric vehicle market continues to expand. At present, power batteries are basically composed of the following systems: battery modules, battery management systems, thermal management systems, electrical and mechanical systems.
(1) The PACK structural design of the lithium battery packs involves many aspects: for example, the mechanical structural design should consider strength, shock resistance, heat dissipation/heating, waterproof and dustproof, etc. Consider electrical design, safety regulations, EMC safety regulations, etc. The design of the lithium battery management system should also be considered, including over-charge, over-discharge, over-temperature, detection accuracy, cell balance, etc. In order to ensure the safety and reliability of the battery, we must go through reasonable design and market verification.
(2) Factors that should be considered in the structural design of the power lithium battery pack:
① Waterproof: the waterproof level should reach IP68. ② Keep the air pressure inside and outside the lithium ion pack balanced. Because the temperature of the battery pack changes during charging and discharging, the air pressure inside the battery pack also changes. The PUW explosion-proof valve can ventilate and prevent water leakage, so that the air pressure in the package is always consistent with the outside world. ③ Explosion-proof: once the lithium battery pack is out of control, the air pressure in the battery pack will rise sharply. At this time, the battery pack is in danger of explosion, so the PUW explosion-proof valve becomes a breakthrough, which can release the pressure quickly and in time.
(3) PACK connection method of lithium battery pack: In the PACK lithium ion pack, in addition to controlling the protection level of the battery pack in terms of safety and reliability, in the case of cooling and heating, attention should also be paid to the connection method of the battery, and the detection accuracy of BMS should also be considered. This problem is widespread, ignoring the impact of voltage drop on the test, resulting in a decrease in the balancing ability of the battery pack.
(4) In the PACK structure of the lithium battery pack, waterproof and shock resistance are very important. Actually, the battery pack is actually a synthesis. There are many issues involved, but it would be nice if the details could be done well.
(5) Structural design of integrated lithium battery pack: After the single module PACK is completed, it needs to be connected in series to form a battery pack. At this time, the fast and safe serial interface form should be considered for serial connection.
(6) Internal insulation design problem in the structural design of battery pack: The insulation problem of positive and negative electrodes has been considered in the battery structural design, but the uncertain factors of vehicle batteries are too complicated, so insulation condition must be set separately in the design process of PACK lipo rechargeable battery to meet the requirements of the battery being safe and effective under various complex environments such as shock, vibration, and humidity.
The above is an explanation of the basic knowledge of battery packs, as well as several main factors affecting the structural design of lithium battery packs. Hope to help everyone. Lithium battery packs may form different market segments in the future, so lithium battery manufacturers are optimistic about this trend and will develop quickly!