A SANTAK500 UPS unit suffered damage due to an unexpected power outage and lack of supervision. Upon reconnecting the AC power, there was no response, and the power indicator remained unlit; disconnecting the AC power yielded the same result—no response, unlit indicator, and no alarm. Upon disassembly and inspection, a foil was found to be open circuit. After restoring it, the issue persisted. The voltages of the two batteries were measured to be 0.5V and 0.75V respectively. Analysis: The copper foil breakage led to the failure of the over-discharge protection circuit, causing excessive discharge of the battery. Solution: The key is to revive the battery. Upon close examination, the batteries are two American-made CHAMPION brand maintenance-free lead-acid batteries, with specifications of 12V/4Ah. Knowing the principle of lead-acid batteries, over-discharge can cause plate sulfation, forming large crystals of sulfuric acid, which have poor conductivity, are large in volume, and block the micro-pores of the plates, hindering the penetration and exchange of the electrolyte, irreversible conversion, and preventing the battery from supplying power to the UPS.
