About this replacement
Eppendorf Xplorer / Xplorer Plus — 3.7V Li-Polymer Replacement Battery (4861 601.000)
This 3.7V, 450mAh Li-Polymer cell replaces the original battery in the Eppendorf Xplorer and Xplorer Plus electronic pipettes. It matches OEM part number 4861 601.000 and H451987. Capacity is 450mAh (1.67Wh) — identical to the factory specification.
- Xplorer and Xplorer Plus compatibility: Both models share the same battery bay dimensions, connector pinout, and BMS handshake protocol. The 74.50 × 21.50 × 5.50mm cell geometry fits the housing without modification, and the charge IC accepts the same current profile on both variants.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the Xplorer platform. The BMS accepted the cell without a fault flag, balanced correctly at top-of-charge, and held voltage within spec through the load profile the pipette motor draws during dispensing cycles.
- Post-swap self-test requirement: After installing this battery, allow the Xplorer to complete its full power-on self-test without interruption. The device runs a BMS verification sequence at startup — cutting power mid-sequence trips a persistent battery fault that will not clear until the next clean reboot from a full charge.
Why the Xplorer reports a low battery alarm immediately after a confirmed full charge
The Xplorer's charge IC calibrates its low-battery threshold against the internal resistance profile of the OEM cell. A new replacement cell has a slightly different impedance signature during the first few cycles, which causes the BMS to read state-of-charge conservatively and trip the alarm early. This is not a faulty cell — it is the BMS learn cycle running on unfamiliar chemistry. Run one complete charge-to-discharge cycle before clinical use. After that cycle, the charge IC updates its reference curve and the alarm threshold stabilises at the correct level.
Xplorer will not power on after the replacement cell sat in storage
Li-Polymer cells self-discharge during storage. If this battery shipped or sat unused long enough to drop below approximately 2.5V per cell, the Xplorer's BMS will refuse to engage — it interprets that voltage as a damaged or over-discharged cell and blocks the power-on sequence as a protection measure. Place the pipette on charge and leave it connected for a full uninterrupted charge cycle. Most BMS controllers re-initialise and accept the cell once it climbs back above the 2.8V recovery threshold.