Most commercial fire alarm control panels use sealed lead-acid backup batteries, which typically need replacement every 3–5 years, depending on manufacturer and usage. However, NFPA 72 doesn't set a fixed replacement calendar — instead, it requires an annual battery test confirming the batteries can still power the system for 24 hours on standby plus 5 minutes in full alarm. If a battery fails that test, or shows visible swelling, leakage, or corrosion, it must be replaced im