Zondan Apollo N5 Replacement Battery 11.1V 5200mAh

Zondan Apollo N5 / ZD120D — 11.1V Li-ion Replacement Battery (LI13S020F)

This is an 11.1V, 5200mAh lithium-ion replacement battery for the Zondan Apollo N5 and ZD120D portable medical devices. It matches the OEM part number LI13S020F and fits the same battery bay without modification. Voltage, capacity, and connector position align with the original specification.

• Apollo N5 and ZD120D compatibility: Both models run the same 11.1V three-cell architecture and share the LI13S020F form factor. The connector pinout and BMS communication protocol are identical across this device family, so one cell works in both.
• Bench tested on actual hardware: We cycled this cell through the Apollo N5 charge and discharge sequence. The BMS handshake completed correctly, charge acceptance tracked as expected, and the protection circuit responded to over-discharge conditions without tripping prematurely.
• Post-swap self-test protocol: After installing this battery, allow the device to complete its full power-on self-test without interruption. Medical-grade BMS firmware on these units runs a cell verification routine at startup — cutting power during that sequence logs a false battery fault that persists until the next clean reboot.

Why the Apollo N5 charges slowly or stops short of 100% on a new cell

The Apollo N5 charge IC applies a conservative current limit when it detects a new or unfamiliar cell. This is deliberate — medical device firmware prioritises cell integrity over charge speed. On the first one or two cycles, the charger may plateau at 95–98% and terminate early rather than push the cell to its full ceiling. This behaviour self-corrects after a complete charge-discharge cycle. No fault is present; the charge IC is applying its safety margin to an unconditioned cell.

Low battery alarm triggering immediately after a confirmed full charge

This happens when the BMS has not yet completed its learn cycle on a new cell. The device measures state-of-charge against a stored profile calibrated to a used OEM cell — a fresh cell with a full charge can read as lower than it actually is until the BMS recalibrates. Run one complete charge-discharge cycle under normal operating load. After that cycle, the BMS updates its reference profile and the alarm threshold aligns correctly. If the alarm persists after two full cycles, check that resting voltage at full charge reads 12.4–12.6V.