Guardian opener LED shows code “13”, battery backup (if equipped) does not function, beeping from unit.

Safety first: Disconnect AC power before servicing the battery. Batteries can leak or vent; handle with care.

• Locate battery: Open the battery compartment on the Guardian opener (if your model has battery backup). Note the voltage and type (often 12V sealed lead-acid).
• Check connections: Ensure the battery harness is firmly plugged into both the battery and the logic board.
• Test battery: Use a multimeter to measure battery voltage. If it is significantly below rated voltage, replace it with a Guardian-approved replacement.
• Replace battery: Install the new battery, observing correct polarity. Secure it in the compartment.
• Test backup: Restore AC power, allow charging for several hours, then unplug AC to confirm the opener runs briefly on battery.
• Replace logic board if needed: If a known-good battery will not charge or the error persists, the charger circuit on the logic board is likely faulty and the board must be replaced.