Schneider considers the safety of lithium batteries from four perspectives

In China, the trend of UPS switching to lithium batteries will become more and more rapid. As a global leader in data center infrastructure solutions and services, Schneider Electric found that in addition to the purchase price factor, Chinese customers now pay attention to safety when choosing UPS lithium batteries. As a relatively large energy storage component in the data center, the safety of lithium batteries largely depends on the following four points, Schneider Electric reminds users to pay attention to the key points when selecting:

Schneider considers the safety of lithium batteries from four perspectives

Schneider considers the safety of lithium batteries from four perspectives

1. High-quality cell production and quality control

At present, the world's leading lithium battery manufacturers have now selected advanced automated production lines, and only through high-quality production process control can we ensure the high quality and high consistency of battery cells. After the production of lithium battery cells is completed, multiple battery cells need to be connected in series and parallel to form a battery module (commonly known as Module), which requires the positive and negative terminals of the battery to be connected, and large manufacturers generally choose a laser welding machine for terminal welding to reduce contact resistance and ensure the reliability of terminal connection. However, small manufacturers generally choose the method of 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.

Because of the strict quality control of lithium batteries, coupled with the fact that their own cycle life has been greatly improved compared with lead-acid batteries, many large brands of lithium batteries can achieve a 10-year warranty in the field of data centers.

2. Perfect BMS planning

BMS (Battery Management System) is the core skill location for the safety of the entire lithium battery system. When the battery has any over-voltage charge, over-current discharge, battery short circuit and other problems, the BMS can quickly cut off the fault current to prevent the risk of thermal runaway of the battery. Schneider Electric believes that the lithium battery BMS should not only monitor the voltage, current, temperature and other conditions of each cell in real time, provide battery health trend analysis, but more importantly, it can actively balance the charge and discharge of the cells, and ultimately improve the consistency of each cell and avoid the failure of the whole group of batteries due to the short board effect of the barrel. At present, the lithium battery manufacturers of international first-line brands are planning to produce BMS by themselves to ensure the functional matching of their battery cells and BMS and the safety of charging and discharging.

3. Chemical information of lithium batteries

As far as the data center UPS is concerned, because of its short-term high-current discharge, large discharge power, long-term standby floating charge and other characteristics, it is more suitable for lithium iron phosphate, lithium manganese oxide, and NCM ternary lithium skills.

Although there are endless debates about energy density and safety, it is undeniable that these controversies are only limited to one aspect of the theoretical function of lithium battery cathode data. Schneider Electric believes that the safety of the lithium battery system requires comprehensive consideration of many elements such as anode data, electrolyte, barrier data, cell shell packaging, battery module grouping, BMS, fuse protection, DC circuit breaker, manufacturing process level, quality control and so on. The problems that occur because of the cathode data of lithium batteries are less than 10% of all lithium battery system problems. Schneider Electric suggests that users should make a comprehensive trade-off for the safety, energy density and cost of UPS lithium batteries, and choose the lithium battery system of large brand companies to get reliable quality assurance.

4. Compatibility test between lithium battery and UPS

Different from lead-acid batteries, lithium batteries come with BMS, which is an intelligent battery with self-control capabilities and communicates with the UPS host. When the lithium battery is fully charged, it will automatically disconnect from the UPS charger, and traditional UPS software planning may think that this is a battery fault and send an alarm. More importantly, the charging and discharging voltage, current, and cut-off voltage of lithium batteries of different materials are different, for example, the additional voltage of lithium iron phosphate cells is 3.2V, while the ternary lithium is 3.8V. Therefore, before using the lithium battery, the UPS needs to conduct a rigorous matching test with it, and the UPS needs to update the firmware for this lithium battery.

It is worth mentioning that the UPS listed by Schneider Electric in recent years now have the compatibility of lithium batteries. The high-rate lithium battery selected by UPS can be charged and discharged in a short period of time and high current, and the corresponding UPS charger planning also needs to adapt to this change. Schneider Electric's new Galaxy V series UPS can charge up to 40% of the additional power output of the UPS (the traditional only 10-15%), such a powerful charger can theoretically quickly charge the lithium battery in 30 minutes - 1 hour.

Schneider considers the safety of lithium batteries from four perspectives

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