GoPro Max 2 Replacement Battery CPPB1B 3.89V 1800mAh

GoPro Max 2 — 3.89V Li-ion Replacement Battery (CPPB1B)

This is a 3.89V, 1800mAh Li-ion replacement cell for the GoPro Max 2 360-degree action camera. It fits the Max 2 directly and matches the OEM part number CPPB1B. Capacity is rated at 7Wh.

• Max 2 specific fit: The Max 2 uses a dedicated battery bay with a BMS handshake that checks cell voltage and internal resistance on insertion. This cell matches the required 3.89V nominal rail and connector pinout so the camera completes that check without rejecting the cell at startup.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the Max 2 body. The BMS accepted the cell on first insertion, charge termination triggered correctly at full voltage, and the protection circuit tripped as expected under simulated over-discharge conditions.
• First-cycle initialisation on the Max 2: Run the first full charge cycle through the camera body itself, not an external charger. The Max 2 BMS maps its battery-remaining display to a charge curve it reads during that first in-body cycle — skipping it can cause the indicator to read inaccurately from the start.

Why the Max 2 battery indicator jumps or reads incorrectly after fitting a replacement cell

The Max 2 tracks remaining charge by mapping voltage thresholds to a discharge curve stored in the camera firmware. A new cell has a slightly different internal resistance profile than a cycled OEM cell, so the voltage readings at each threshold don't align perfectly on first use. This causes the percentage display to jump — commonly dropping several points at once mid-use or showing full charge until the cell is nearly flat. One complete charge-discharge cycle through the camera body resets the mapping. After that cycle, the indicator stabilises and tracks accurately.

Max 2 showing a dead battery icon on a cell you know has charge

This happens when a replacement cell's resting voltage has dropped below the camera's minimum boot threshold — typically around 3.0V — due to storage discharge. The Max 2 won't initialise below that floor and shows a dead battery indicator instead of attempting to charge. Place the cell in an external Li-ion charger set to 3.89V nominal and bring it up to at least 3.2V. Once it crosses that threshold, insert it into the camera body and let the Max 2 complete the charge from there.