About this replacement
JDSU WiFi Advisor / Viavi SC-TPS — 7.4V Li-ion Replacement Battery (21108524)
This 7.4V 6800mAh Li-ion pack replaces OEM part 21108524 in JDSU and Viavi field test instruments, including the WiFi Advisor Wireless LAN Analyzer, SC-TPS, and units carrying model numbers 21129596 000 and 21100729 000. These are handheld optical and wireless test platforms used in active fiber and LAN network diagnostics. Capacity is 6800mAh (50.32Wh).
- Cross-model fit — 21129596 000, 21100729 000, WiFi Advisor, SC-TPS: These units share the same battery bay geometry, 7.4V power rail, and BMS handshake protocol. One pack covers all four fit models without modification.
- Bench tested on actual hardware: We cycled this pack under sustained RF scanning and optical measurement loads. The BMS held voltage within spec through probe initialisation spikes and maintained stable output across logging sessions without tripping cutoff.
- Post-install calibration cycle: After fitting this pack, run a full calibration cycle through the instrument menu before deploying to the field. The instrument maps battery state during that routine — skipping it causes the low-battery indicator to fire prematurely on your first measurement session.
BMS lockout after the instrument sat unused in a carry case for months
Li-ion cells self-discharge over storage. If the pack drops below roughly 2.5V per cell while sitting idle, the BMS trips a deep-discharge lockout and the instrument will not power on — even on charge. The fix is to connect the charger and leave it for at least 30–60 minutes before attempting to power the unit. Most BMS circuits include a trickle-recovery mode that brings cells back up to the minimum threshold before allowing full charge current.
Readings resetting or dropping out mid-logging session
This is a voltage dropout issue, not a capacity issue. Sustained sensor or RF loads pull higher current than the standby draw the instrument was calibrated against, causing momentary voltage sag that the instrument interprets as a low-battery condition. A worn or partially degraded cell shows this much earlier in the charge cycle. Replacing the pack and running the calibration cycle through the instrument menu resolves the threshold mismatch — confirm cell voltage reads above 7.0V under load before deployment.