Lucky Duck Agitator HDi Replacement Battery 11.1V 5200mAh

Lucky Duck Agitator HDi Series — 11.1V Li-ion Replacement Battery (21-11120-8)

This is an 11.1V 5200mAh Li-ion replacement battery for the Lucky Duck Agitator HDi Drake, Hen & Goose, and Kennel Fan. It uses OEM part number 21-11120-8 and matches the original voltage and capacity spec. The battery connects directly to the motorized decoy's drive system with no modification needed.

• Agitator HDi Drake, Hen & Goose, and Kennel Fan compatibility: These three models share the same 11.1V three-cell Li-ion architecture, connector type, and BMS handshake protocol — which is why one part number covers all three. Swapping between units carries no electrical risk if the OEM part number matches.
• Bench tested on actual hardware: We ran this pack through full charge and discharge cycles on a matched load. The BMS held cell balance within spec, and the protection circuit tripped correctly at the low-voltage cutoff threshold — no false shutdowns during steady motor draw.
• Cold-weather pre-warming: Li-ion cells lose 15–25% usable capacity at 0°C and up to 40% at -20°C. Keep this battery in an inner jacket pocket until just before deploying the decoy. A warm cell put into the unit at the water's edge holds significantly more capacity than one that sat in a cold blind bag all morning.

Why the Agitator HDi slows down or stops mid-session in cold water

Cold water conducts heat away from the battery housing faster than ambient air. Even if the air temperature is mild, a partially submerged decoy can pull the cell pack below 5°C within minutes. At that temperature, internal resistance rises sharply, and the BMS may interpret the resulting voltage sag as a low-cell event and cut motor power. The fix is simple — keep the battery warm until the last moment before deployment and avoid leaving the decoy stationary in water between sets.

Decoy won't power on after sitting in storage between seasons

Li-ion cells self-discharge at roughly 1–3% per month at room temperature. After several months of off-season storage, a partially charged pack can drop below the BMS minimum boot voltage — typically around 9V for an 11.1V three-cell pack — and the protection circuit will block output entirely. Connect the battery to the original charger and leave it for a full charge cycle before assuming it has failed. If the charger light activates and completes the cycle, the pack has recovered; if it shows no response after 30 minutes, cell voltage has likely fallen below the charger's wake threshold at approximately 8.1V.