Viavi JDSU Smartclass E1 2M 4.8V Ni-MH Replacement Battery

Viavi JDSU Smartclass E1 2M / VDSL ADSL TPS — 4.8V Ni-MH Replacement Battery (21100729 000)

This is a 4.8V 3500mAh Ni-MH replacement battery for the Viavi JDSU Smartclass E1 2M and VDSL ADSL TPS portable network testers. These instruments are used in the field for E1, ADSL, and VDSL line diagnostics and performance testing. The battery replaces OEM part numbers 21100729 000 and 0718081TPS.

• Smartclass E1 2M and VDSL ADSL TPS compatibility: Both instruments share the same 4.8V Ni-MH cell configuration, connector footprint, and BMS handshake protocol — that is why a single pack covers both platforms without modification.
• Bench tested on actual hardware: We ran this pack through the Smartclass E1 2M power-on sequence, triggered a full port scan cycle, and monitored the BMS under sustained measurement load. The pack held voltage within spec throughout logging and did not trip the protection circuit during probe initialisation.
• Post-install calibration cycle: After fitting this battery, run a full calibration cycle through the instrument's system menu before deploying to site. The Smartclass maps battery state during calibration — skipping this step causes the low-battery warning to fire early on the first measurement session, even when the pack is fully charged.

BMS lockout after the Smartclass sat unused in a carry case for months

Ni-MH packs self-discharge during storage. If the Smartclass E1 2M sat in a case long enough, the pack voltage can drop below the BMS recovery threshold, and the instrument will not power on even when connected to the charger. The BMS enters a protection state to prevent cell reversal and blocks normal charge current. To recover the pack, apply a slow trickle charge at the correct voltage using a compatible external Ni-MH charger until the cells reach approximately 4.2V — at that point the BMS re-initialises and the instrument's internal charger can take over.

Smartclass E1 2M shuts down mid-measurement despite a charged battery

This happens when the instrument initiates a new test sequence and the resulting current draw spikes above what an aged or partially discharged cell can deliver without a voltage sag. The BMS interprets the sag as an undervoltage fault and cuts the output to protect the cells. It is not a charge level problem — it is a peak current delivery problem that degrades as cells age. If the shut-off happens consistently at the start of a port scan or line test, check the pack's resting voltage with a multimeter; a healthy 4.8V Ni-MH pack at full charge should read at least 5.4V at rest before load is applied.