Inogen G4 OxyGo 14.4V Replacement Battery 1400-2010-4

Inogen One G4 / G4 OxyGo — 14.4V Li-ion Replacement Battery (1400-2010-4)

This 14.4V, 3500mAh (50.4Wh) lithium-ion battery replaces the OEM pack in the Inogen One G4 and G4 OxyGo portable oxygen concentrators. It matches the original electrical specification and connector configuration for those two units. OEM part numbers covered: 1400-2010-4, BA-400, BA-403, BA-408, and IO-400.

• One G4 and G4 OxyGo compatibility: Both devices run the same 14.4V power rail, use the same battery bay connector, and share a BMS handshake protocol. A single cell design covers both units — there is no electrical difference between the two platforms at the battery interface.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the G4 platform. The BMS accepted the pack without a fault flag, completed its verification handshake, and delivered consistent voltage output across the full state-of-charge range.
• Power-on self-test protocol: After installing this battery, let the G4 complete its full boot sequence without interruption. The device runs a BMS verification check at startup. Cutting power mid-sequence triggers a battery fault that the unit will hold until the next clean reboot from a fully charged state.

Why the G4 OxyGo reports a battery error on a new cell

The G4 OxyGo BMS uses stored charge-cycle data to validate a battery pack. A new cell arrives with no cycle history, so the BMS applies conservative pass/fail thresholds during its first self-test. This can trip an error flag even when the pack is fully charged and electrically sound. Running one complete charge-to-discharge-to-full-charge cycle writes baseline data to the BMS and clears the threshold flag. After that first cycle, the device treats the pack as a known unit and self-test passes cleanly.

G4 showing low battery alarm immediately after a confirmed full charge

This alarm fires when the BMS reads terminal voltage instead of validated state-of-charge data — a distinction that matters on the first few cycles of a new cell. Fresh lithium-ion cells have a slightly compressed voltage curve until the chemistry stabilises, which causes the charge IC to report a lower apparent capacity than is actually present. The fix is to complete two full charge-discharge cycles before relying on the battery indicator in clinical use. After cycle two, the BMS recalibrates its state-of-charge model against the actual cell curve and the alarm clears at correct charge levels.