Motorola MBP853 Replacement Battery 3.6V 1000mAh

Motorola MBP853 / MBP668 Series — 3.6V Ni-MH Replacement Battery (GB390822)

This 3.6V, 1000mAh Ni-MH battery replaces the rechargeable cell in the Motorola MBP853, MBP853PU, MBP853CONNECTPU, MBP668, and related parent units. It matches OEM part numbers GB390822, TFL3X44AAA900-CB94-01A, and GPRHCH93C021. When the original cell loses charge capacity, the parent unit becomes tethered to the wall — this battery restores wireless operation.

• MBP853 and MBP668 parent unit fit: These models share the same battery bay dimensions and 3.6V supply rail. The cell slots in using the same three-cell AAA Ni-MH configuration across this monitor family, so voltage handshake to the parent unit circuit board is consistent.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the MBP853 parent unit. The onboard charging circuit accepted the cell without fault codes, and the BMS terminated charge correctly at full cell voltage.
• Post-swap pairing step: After fitting a new battery, re-pair the parent unit with the camera unit. A full power loss — which happens during battery replacement — clears the active wireless link on this monitor. Hold the pair button on the camera unit until the parent unit confirms connection.

Why the MBP853 parent unit shows low battery immediately after a new cell is fitted

Ni-MH cells ship in a partially discharged state — typically 30–50% capacity — to reduce degradation during storage. The MBP853 parent unit reads cell voltage directly, and a resting voltage below roughly 3.9V will trigger the low-battery indicator. This is not a faulty cell. Place the parent unit on its charging cradle for a full charge cycle before drawing conclusions about battery condition. A full charge brings resting voltage to approximately 4.1–4.2V across the three cells, and the indicator clears.

MBP853 range dropping noticeably compared to the original battery

The DECT radio transmitter in the parent unit draws more current than the display or speaker — it is the most voltage-sensitive load in the unit. If the replacement cell is not fully charged, the transmitter operates below its rated voltage and RF output drops, cutting effective range. This is the most common cause of "weak signal" reports after a battery swap, and it is not a hardware fault. Charge the parent unit fully on the cradle before testing range — at full charge, the cell should sustain 3.6V under load and restore normal transmission power.