There are many reasons for the UPS battery to catch fire. The first situation is the corrosion of the electrode joints inside the UPS battery and the short circuit of the plates. The reason is that too much dust has accumulated on the UPS battery, and the dust itself contains various unknown objects, which will cause the joints of electronic equipment to corrode and short-circuit.

    In addition, when the battery pack is charged and discharged, the temperature of the contact point rises sharply, resulting in a short circuit of the terminal (connecting piece) and the melting of the casing, which will also cause the battery to misfire.​​

    The backup battery bank of large and medium-sized UPS power supply systems is usually composed of dozens or even hundreds of batteries in series and parallel, and the unreasonable wiring design between the battery banks, especially the irregular construction, is an important cause of fire accidents.

    (1) Faults such as overloading, grounding, and local contact resistance are too large, which can lead to overheating of the cable and melting and burning of the insulation layer. Because the energy of the DC power supply is very large, once a problem occurs and cannot be found in time, a fire will inevitably occur.

    (2) When leakage or grounding fault occurs in the line, the leakage current can easily ignite the surrounding combustibles and cause a fire.

    (3) In the event of a short circuit, the high-temperature effect of the strong arc can rapidly melt, vaporize or ignite the surrounding combustibles by the local metal of the copper wire, and aggravate the spread of the fire. The hydrogen leaked further, causing the equipment to burn on a larger scale; in addition, because the cable lines had been ignited, the system cables were constantly jumping and short-circuiting, resulting in the further spread of the fire.