Compared with lead-acid batteries, lithium batteries have unparalleled technical advantages: several times the energy density of lead-acid batteries to reduce the footprint of lithium batteries by more than 60%; Weight reduction of more than 70%; Better adaptability to high temperatures; After discharge, it can be quickly recharged, and the number of cycles is 4 times that of lead-acid batteries. The long life design of 10-15 years and the high number of cycles make the lithium battery need not be replaced during the 10-year life cycle of the UPS, reducing maintenance and replacement costs, and ultimately helping users reduce TCO and obtain maximum business value.

1. High-quality cell production and quality control

At present, the world's top lithium battery manufacturers have adopted advanced automated production lines, and only through high-quality production process control can we ensure the high quality and high consistency of the battery cell. After the production of lithium cells, it is necessary to form a battery Module (commonly known as Module) through a series of parallel cells, which requires the positive and negative extremes of the battery to be connected, and large manufacturers usually use laser welding machines for terminal welding to reduce contact resistance and ensure the reliability of terminal connection. However, small manufacturers generally use manual bolt and nut crimping, which is difficult to ensure the reliable connection of terminals, which may bring hidden dangers to long-term operation in the future.
Due to the strict quality control of lithium batteries, and their own cycle life has been greatly improved compared with lead-acid batteries, so in the field of data centers, many large brands of lithium batteries can achieve longer warranty.

2. Perfect BMS design

BMS (Battery Management System) is the core technology for the safety of the entire lithium battery system. When the battery occurs any overvoltage charging, over-discharge, battery short circuit and other faults, the fault current can be quickly cut off through BMS to prevent the risk of thermal runaway of the battery. Schneider Electric believes that lithium battery BMS should not only monitor the voltage, current, temperature and other states of each cell in real time, provide battery health trend analysis, but more importantly, it can actively balance the charge and discharge of the cell, and ultimately improve the consistency of each cell to avoid the entire battery failure caused by the short board effect of the wooden barrel.

3. Chemical materials for lithium batteries

For data center UPS, due to its short time large current discharge, large discharge power, long-term backup floating charge and other application characteristics, the more suitable is lithium iron phosphate, lithium manganese acid, NCM terpolymer lithium technology.
The market is mainly ternary lithium and lithium iron phosphate, although the two in the energy density and safety of the debate, but it is undeniable that these debates are only limited to one aspect of the theoretical performance of lithium battery cathode materials. However, the safety of the lithium battery system needs to consider many factors such as negative electrode material, electrolyte, diaphragm material, cell shell packaging, battery module group, BMS, fuse protection, DC circuit breaker, production and manufacturing process level, quality control and so on.

4. Compatibility test between lithium battery and UPS

Unlike lead-acid batteries, lithium batteries come with BMS, which is a kind of intelligent battery with self-control ability. When the lithium battery is fully charged, it will automatically disengage from the UPS charger, and the traditional UPS software design may think that this is a battery failure and issue an alarm. More importantly, due to the problem of cell consistency, the charge and discharge voltage, current, and cut-off voltage of the same type of lithium battery will also be different. Therefore, before using the lithium battery, the UPS needs to perform a strict match test with it, and it is necessary to update the firmware of the UPS for this lithium battery.