Design life is a classification from accelerated float testing at 20 °C (EUROBAT: 3–5 / 6–9 / 10–12 / over 12 years). Service life is what field experience delivers under good conditions. Warranty is a contractual term, usually much shorter. Australian specifiers state life requirements explicitly, TMR requires 10 years minimum for LiFePOâ‚„ roadside UPS, Sydney Water requires 10 years for batteries and 20 for chargers, and ARTC asks for a design life over 10 years with a 12-month warranty. /battery-design-life-vs-service-life/