Mares ICON HD Dive Computer Replacement Battery 3.7V 3350mAh

MARES ICON HD / ICON Genius / Genius Air — 3.7V Li-ion Replacement Battery (44201389)

This 3.7V, 3350mAh Li-ion cell replaces the OEM battery in the MARES ICON HD, ICON Genius, and Genius Air dive computers. These wrist-mounted units use the battery to power continuous depth tracking, dive logging, and GPS acquisition during and between dives. Capacity figure is taken directly from product data — 3350mAh, 12.4Wh.

• ICON HD, ICON Genius, and Genius Air shared platform: All three models run the same 3.7V cell on the same connector and BMS handshake profile. The ICON Genius and Genius Air add air integration, but the power circuit is unchanged — one cell covers the full range without modification.
• Bench tested on actual hardware: We cycled this cell through the ICON HD's logging and GPS acquisition states. The BMS held the charge curve cleanly, and the protection circuit tripped at the correct low-voltage threshold without false cutoff during GPS lock sequences.
• Cold-start satellite acquisition after fitting: After any full power removal, the GPS module loses its ephemeris data and performs a cold start. Take the computer outdoors and power it on fully before your first post-swap dive — first satellite fix takes 5–10 minutes. Subsequent warm starts resolve in under a minute.

Why the ICON HD shuts off without warning at low battery

After an aged battery degrades, its internal resistance climbs. The cell voltage reads acceptable at rest but sags sharply the moment the GPS receiver or backlight draws current. The dive computer's low-battery indicator reads the rested voltage, not the load voltage — so the warning threshold is never triggered before the BMS cuts the cell to prevent over-discharge. A new cell with lower internal resistance holds voltage under load and restores accurate battery indicator behaviour. If the issue persists after swap, recalibrate the indicator by running three full charge-discharge cycles.

GPS accuracy dropping as battery level falls

The ICON HD's GPS receiver draws peak current during active satellite tracking. At low state-of-charge, some firmware revisions throttle receiver sensitivity to protect the cell from undervoltage cutoff. The result is fewer satellites tracked and reduced position accuracy — showing up as drift on logged dive surface intervals or GPS waypoints. Fitting a fresh 3350mAh cell restores full receiver power budget. Confirm the fix by checking satellite count in the GPS status screen — a healthy unit should lock onto six or more satellites in open sky.