About this replacement
Zondan ZD120B / D120D / Apollo N1-A — 14.8V Li-ion Replacement Battery (WP-XHT-102A)
This is a 14.8V, 2600mAh Li-ion battery for the Zondan ZD120B, D120D, and Apollo N1-A portable medical devices. It replaces OEM part numbers WP-XHT-102A and GHOTA-99G-00. Capacity is 38.48Wh — drawn directly from product specifications, not estimated.
- ZD120B, D120D, and Apollo N1-A compatibility: All three models share the same 14.8V four-cell Li-ion architecture and BMS communication protocol. The connector pinout and charge termination logic are identical across this platform, so one cell fits all three without firmware or hardware modification.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the ZD120B platform. The BMS handshake completed without fault flags, and charge termination triggered correctly at 16.8V. No false low-battery alarms appeared after the first full charge-discharge cycle.
- Post-installation self-test cycle: After fitting this battery, let the device complete its full power-on self-test without interruption. Medical devices on this platform run BMS verification at startup — cutting power during that sequence triggers a false battery fault that persists until the next complete reboot.
Device not completing boot sequence on new battery
Some ZD120B and D120D units stall mid-boot when a new cell is installed straight from the box. The BMS has not yet built a charge history, so the device firmware reads the cell state as unverified and halts the sequence. This is not a faulty battery — it is a first-cycle BMS learn state. Charge the battery to full, allow the device to complete one uninterrupted boot, and the issue clears on subsequent power cycles.
Low battery alarm triggers immediately after a confirmed full charge
This happens when the device's charge-verification threshold is calibrated to OEM cell chemistry. A new replacement cell may read slightly below the alarm threshold on its first cycle because the internal resistance has not yet stabilised. Run one full charge-discharge cycle before clinical use — after that cycle, the BMS recalibrates its state-of-charge mapping to the new cell. If the alarm persists after two full cycles, check that the charger reached 16.8V at termination.