Selecting the correct battery requires balancing capacity (Ah), discharge rate, and service life. For UPS applications, High-Rate Discharge batteries are preferred as they can provide significant power in short bursts. Ensure the battery uses Absorbent Glass Mat (AGM) or Gel technology, as these are maintenance-free (VRLA) and leak-proof, making them safer for indoor server rooms. Always verify the Cycle Life (typically 300-500 cycles at 50% DOD) and the Design Life (5-10 years) to ensure long-term reliability.