McMurdo 82-970A Compatible Battery 9V 1350mAh Li-MnO2

McMurdo A5 / E5 / G5 Series — 9V Li-MnO2 Replacement Battery (82-970A)

This is a 9V, 1350mAh lithium-manganese dioxide battery for the McMurdo A5, A5G, E5, and G5 personal locator beacons and marine safety devices. It replaces OEM part numbers 82-970A and 82-939D. Li-MnO2 chemistry is mandatory for this class of device — standard alkaline or lithium-ion cells will not meet the activation voltage or temperature range these beacons require.

• A5, A5G, E5, G5 compatibility: These McMurdo models share the same battery bay geometry, connector, and 9V activation threshold. The beacon's internal circuit monitors battery voltage at power-on and during self-test — a cell below spec triggers a fault state before any transmission begins.
• Bench tested on actual hardware: We ran this cell through the self-test cycle and confirmed the BMS accepted the battery without fault codes. Activation voltage held within the beacon's required threshold across the full test sequence.
• Post-replacement registration check: After fitting a new battery, verify your beacon's registration with your national authority — COSPAS-SARSAT registration records can lapse after maintenance, and an unregistered beacon may delay rescue response even if the device transmits correctly.

McMurdo A5 not activating on battery self-test

The A5's self-test circuit checks battery voltage before allowing the activation sequence to proceed. Li-MnO2 cells lose capacity gradually over their shelf life even without use — a cell that reads 9V on a basic multimeter can still fail the beacon's internal load test. McMurdo specifies mandatory battery replacement intervals regardless of usage history, because a depleted cell at sea will not sustain the 406MHz transmission the beacon needs to reach satellites. If your self-test returns a fault, fit a fresh cell and rerun the test before the beacon goes back into service.

Beacon self-test LED fault pattern after battery swap

A new battery that seats incorrectly can cause the LED fault pattern to mimic a depleted cell — the beacon cannot distinguish between low voltage and a poor contact. Check that the battery terminals are fully seated and the battery door is closed until it clicks; a partial connection drops voltage under load and triggers the same fault code as an expired battery. If the LED pattern persists after reseating, check the contact pins inside the bay for corrosion — salt air accelerates oxidation on exposed copper. Clean the pins with a dry cloth, reseat the battery, and rerun the self-test to confirm a clean pass.