Buyers must first identify the battery chemistry (Lead-Acid, AGM, Gel, or LiFePO4) as this dictates performance. For starting applications (SLI), focus on Cold Cranking Amps (CCA) to ensure engine ignition in low temperatures. For solar or marine use, prioritize Deep Cycle capabilities and Amp-Hour (Ah) ratings, which indicate energy capacity. Additionally, verify the Cycle Life; for instance, LiFePO4 batteries typically offer 3,000-5,000 cycles, significantly outperforming traditional lead-acid options.