FiberPa OTDR OT-8800 Replacement Battery 10.8V 6600mAh

FiberPa OTDR OT-8800 / OT-8810 / OT-8820 — 10.8V Li-ion Replacement Battery

This 10.8V 6600mAh (71.28Wh) lithium-ion battery fits the FiberPa OTDR OT-8800, OT-8810, OT-8820, and SGT-18A optical time-domain reflectometers. These units are used in field cable diagnostics and fiber optic testing, where a dead battery mid-job means abandoned test runs and incomplete splice reports. Capacity figures are taken directly from the product specification — 6600mAh at 10.8V nominal.

• OT-8800 / OT-8810 / OT-8820 / SGT-18A platform: These four models share the same 10.8V battery rail, connector pinout, and BMS handshake protocol. A single cell swap covers the full platform without any connector modification or firmware difference to account for.
• Bench tested on actual hardware: We cycled this cell through charge, full discharge, and reinitialisation on the OT-8800 platform. The BMS completed its verification handshake cleanly, and the charge indicator advanced to 100% without fault codes after the first full cycle.
• Post-swap self-test protocol: After fitting this battery, allow the OTDR to complete its full power-on self-test sequence without interruption. These instruments run a BMS verification routine at startup — cutting power during that window triggers a persistent false battery fault that does not clear until the next complete reboot cycle.

Why the OT-8800 reports a battery fault after a confirmed full charge

The OT-8800 BMS stores a capacity baseline from the previous cell and compares it against the new cell's first reported state-of-charge. A fresh lithium-ion cell reports slightly different internal resistance and open-circuit voltage than a worn OEM cell, so the BMS flags it as out of spec. This is not a cell defect — it is the BMS applying thresholds calibrated to the old chemistry profile. One complete charge-discharge cycle allows the BMS to update its baseline and clear the fault automatically.

OTDR shuts off unexpectedly during a live fiber test

During the first several charge cycles, a new lithium-ion cell has not yet reached its full charge-acceptance capacity — internal resistance is slightly elevated compared to a broken-in cell. When the OT-8800 drives the laser and acquisition circuitry simultaneously, the momentary current draw causes a voltage sag that crosses the BMS low-voltage cutoff threshold prematurely. This is most common in the first five to ten cycles and resolves as the cell breaks in. If it continues past ten cycles, check that the battery contact pins on the instrument are clean and making full contact — corroded pins increase resistance and worsen sag at the same draw level.