Buyers must first identify the battery chemistry (Lead-Acid, AGM, Gel, or LiFePO4) as this dictates performance. For deep-cycle applications like solar storage or RVs, prioritize LiFePO4 (Lithium Iron Phosphate) for its higher energy density and longer cycle life (3000-5000 cycles). For automotive starting needs, focus on Cold Cranking Amps (CCA). Always verify the Amp-Hour (Ah) rating to ensure it meets the duration requirements of the intended load, and check for a built-in Battery Management System (BMS) in lithium variants to prevent overcharging and thermal runaway.