About this replacement
Viavi 120 DSP / Seeker Series — 3.7V Li-ion Replacement Battery (0090048000)
This 3.7V 3350mAh Li-ion battery replaces the original pack in the Viavi 120 DSP and Seeker series leakage detectors, including the Seeker, Seeker D, and Seeker D Lite. It matches the OEM part number 0090048000 and the cross-reference 6233224-019010-MX. Capacity is 12.4Wh — identical to the factory specification.
- 120 DSP and Seeker platform fit: These instruments share a common battery bay, connector pinout, and BMS handshake protocol across the Seeker family. The same cell format and communication lines serve all listed models, so one pack covers field kits that carry multiple Viavi units.
- Bench tested on actual hardware: We cycled this pack under simulated probe-initialisation loads — the current spike at sensor power-up can trip an undersized BMS. This cell held voltage above the cutoff threshold through repeated initialisation events without triggering a shutdown.
- First-deployment calibration step: After installing the pack, run a full calibration cycle through the instrument menu before heading into the field. The 120 DSP maps battery state during calibration — skipping this causes premature low-battery warnings partway through your first measurement session, even with a full charge.
BMS lockout after the Viavi unit sat unused in a carry case for months
Li-ion cells self-discharge slowly in storage. If the pack drops below roughly 2.5V per cell while the instrument sits unused, the BMS trips a deep-discharge lockout and the device will not power on — even when connected to a charger. The BMS interprets the depleted voltage as a damaged cell and blocks charging current as a safety measure. To recover, connect the charger and leave it for 45–60 minutes without attempting to power the unit on; most BMS circuits will accept a trickle recovery charge once the cell climbs above 2.7V and will then resume normal charging.
Viavi 120 DSP powers on but shuts off during USB data transfer to a PC
USB data transfer activates both the processor and the USB controller simultaneously, pushing total current draw above what the battery supplies at rest. If the cell voltage is already soft — sitting below 3.6V at rest — this combined load causes a momentary voltage sag that crosses the BMS undervoltage cutoff, and the instrument shuts down mid-transfer. Charge the pack fully before any transfer session and confirm resting voltage reads at or above 3.7V before connecting the USB cable. If shutdowns continue on a fully charged pack, the cell has degraded and needs replacing.