Viavi SmartOTDR Replacement Battery 7.4V 5000mAh

Viavi SmartOTDR / MTS-2000 Handheld Fiber Tester — 7.4V Li-Polymer Replacement Battery

This 7.4V 5000mAh (37Wh) Li-Polymer pack replaces the internal battery in the Viavi SmartOTDR Handheld Fiber Tester, T-BERD, and MTS-2000 Handheld Modular Test Set. These instruments are used in the field for optical fiber fault location, end-to-end loss measurement, and network verification. Dimensions are 103.82 × 61.40 × 12.05mm — confirm clearance before ordering if your unit has been serviced previously.

• SmartOTDR, T-BERD, and MTS-2000 compatibility: All three platforms share a 7.4V nominal rail and the same physical battery bay dimensions. The BMS handshake on each expects a pack that holds above the instrument's low-voltage cutoff threshold during OTDR pulse transmission — a moment of elevated draw that weaker packs fail to sustain.
• Bench tested on actual hardware: We cycled this pack under simulated OTDR trace loads, including the current spike during laser module initialisation. The BMS held the output rail stable and did not trigger protective cutoff during repeated acquisition sequences.
• Post-install calibration cycle: After fitting this pack, run a full calibration cycle through the instrument's system menu before field deployment. The instrument maps battery state-of-charge during calibration — skipping this step causes the battery indicator to report premature low-battery warnings during your first measurement session.

BMS cutoff during OTDR laser module power-up

When the SmartOTDR initialises its laser module, the current draw spikes sharply for a fraction of a second. An aged or deeply discharged pack may sit at a voltage that looks acceptable on the display but drops below the BMS cutoff threshold the moment that spike hits. The instrument shuts down immediately — often before the acquisition screen fully loads. A fresh, fully charged pack handles this spike without the voltage rail sagging below cutoff. Charge to full (8.4V at the pack terminals) before the first field session.

Instrument won't recognise new pack after extended storage in carry case

Li-Polymer cells left unused for several months self-discharge below 3.0V per cell. At that level, the BMS enters a sleep state and stops communicating with the instrument entirely — the device either shows no battery icon or refuses to power on. Most chargers won't attempt to charge a pack the BMS is presenting as absent. Apply a compatible charger that supports recovery charging, or leave the pack connected to the instrument charger for 20–30 minutes — many units will trickle enough current through to wake the BMS once cell voltage climbs back above 3.2V per cell.