Urmet ZEFFIRO 3 Replacement Battery 4.8V 1800mAh

Urmet ZEFFIRO 3 — 4.8V Ni-MH Replacement Battery

This is a 4.8V, 1800mAh Ni-MH battery pack for the Urmet ZEFFIRO 3 cordless handset. It slots into the handset battery compartment and restores power to the DECT phone after the original cells have degraded. Capacity is rated at 8.64Wh.

• ZEFFIRO 3 handset fit: The ZEFFIRO 3 base station charges at a voltage and current profile matched to a 4.8V Ni-MH pack. Swapping to a different voltage or chemistry will confuse the base charger circuit, so this replacement keeps the same cell count and chemistry as the original.
• Bench tested on actual hardware: We cycled this pack through charge and discharge on a cordless phone test rig. The BMS accepted charge from a standard DECT base station without triggering any fault condition, and cell voltage balanced across all four cells within two full cycles.
• First-charge protocol for Ni-MH handsets: Place the handset in the base for a full 16 hours before first use. Ni-MH cells arrive partially discharged from storage — skipping this slow initial charge leaves cells unbalanced and talk time noticeably shorter than rated for the first several cycles.

Talk time shorter than the original battery after replacement

Ni-MH cells do not reach rated capacity on the first charge. The electrodes need three to five full charge-discharge cycles before the chemistry stabilises at full capacity. If talk time seems low after the first charge, run the handset until it beeps low, return it to the base for a full 16-hour charge, and repeat. By cycle five, capacity should be at or near the rated 1800mAh.

Base station showing no-charge or error light with new pack installed

A Ni-MH pack that has sat in storage can drop below 4.0V total — the threshold some DECT base stations require before they recognise a valid battery and begin charging. The base charger sees a voltage it treats as a fault rather than a discharged pack. To recover, some bases will accept the pack if left seated for 30 minutes with the handset fully docked; the trickle stage eventually pulls the voltage up to the acceptance threshold. If the error light persists, check the contact pins on both the handset and base are clean and making full contact.