SeaLife Reefmaster DC 800 Compatible Battery 3.7V 1250mAh

SeaLife Reefmaster DC 800 / DC 1000 — 3.7V Li-ion Replacement Battery (D018-05-8023)

This is a 3.7V, 1250mAh Li-ion replacement battery for the SeaLife Reefmaster DC 800 and DC 1000 underwater cameras. It matches OEM part number D018-05-8023 and fits both the DC800 and DC1000 body variants. Capacity is 4.63Wh — identical to the factory cell.

• DC 800 and DC 1000 compatibility: Both cameras use the same battery bay dimensions, connector pinout, and BMS communication protocol. One cell covers both bodies — no hardware difference between the two on the power side.
• Bench tested on actual hardware: We ran this cell through the DC 800 body. The BMS accepted the cell without a rejection flag, charge termination triggered correctly at 4.2V, and discharge tracking remained consistent through multiple cycles.
• Underwater housing and battery removal: Salt water and humidity accelerate corrosion on the battery contacts. After every dive, remove the battery from the housing, rinse the contacts with fresh water, and dry them before reinserting. Corroded contacts cause voltage drop that the camera reads as a low-battery condition even on a full cell.

Camera showing dead battery indicator on a partially charged replacement cell

The Reefmaster DC 800 maps its battery indicator to voltage thresholds calibrated against the original cell's discharge curve. A new third-party cell may present a slightly different open-circuit voltage at rest, causing the indicator to show empty when the cell is not. The fix is to perform one full charge cycle through the camera body or OEM charger before taking it into the water. After that first full cycle, the indicator typically tracks the actual charge state accurately.

Battery percentage jumping erratically on the DC 800 display

This happens when the camera's fuel gauge loses its reference point — usually after a deeply discharged cell or a swap with no charge cycle in between. The camera is estimating state of charge from voltage alone, and small load fluctuations shift the reading. Charge the replacement cell to 100% via the OEM charger, then discharge it fully in-camera in a single session. That one calibration cycle re-anchors the voltage-to-percentage map and stabilises the readout. Confirmed stable at 3.7V nominal after calibration in our bench test.