iRobot Roomba Combo 12V Replacement Battery 4720110

iRobot Roomba Combo — 12V Ni-MH Replacement Battery (4720110)

This is a 12V 3000mAh Ni-MH replacement battery for the iRobot Roomba Combo robotic vacuum cleaner. It replaces OEM part number 4720110 and fits directly into the Roomba Combo battery bay. Capacity is rated at 36Wh, matching the original specification.

• Roomba Combo fit: The Roomba Combo uses a 12V Ni-MH pack with a specific cell arrangement to clear the chassis clearance. This replacement matches that cell layout, connector orientation, and voltage rail so the unit's motor controller sees the correct supply from startup.
• Bench tested on actual hardware: We ran this pack through charge and discharge cycles on the Roomba Combo platform. The BMS held cutoff voltage correctly on both low-charge shutdown and motor-start surge without tripping prematurely.
• Dock charging habit on the Roomba Combo: Leaving the Roomba Combo on its home base continuously accelerates capacity fade in Ni-MH cells. Charge to full, then remove the unit from the dock. Return it to the dock only when the battery is depleted.

Suction dropping before the battery indicator reaches low

Ni-MH cells in the Roomba Combo deliver voltage that sags under load before the pack is fully depleted. When the motor draws hard — especially on carpet or with a partially blocked filter — voltage can drop enough to reduce fan speed noticeably while the indicator still reads mid-charge. This is not a faulty battery; it is a real-time voltage response to sustained high current draw. Clear the filter and check the brush roller for hair wrap to reduce the load the motor is pulling.

Motor cuts out mid-clean then recovers after a short pause

This is a BMS overcurrent trip, not a dead battery. When suction is restricted — blocked filter, tangled brush, or debris in the intake — the motor draws above its rated current threshold and the BMS cuts the circuit to protect the cells. The pack resets after a brief cool-down, which is why the unit restarts. Clean the filter first, then check the intake path. If the trip repeats on a clean filter, measure pack voltage at rest — it should read at least 12.0V on a full charge.