EnGenius RB-SP922-L DuraFon 1x Compatible Battery 3.7V 1800mAh

EnGenius DuraFon 1x / 4x Series — 3.7V Li-ion Replacement Battery (RB-SP922-L)

This 3.7V, 1800mAh Li-ion battery replaces part number RB-SP922-L in the EnGenius DuraFon 1x, DuraFon 4x, DuraFon Pro, and Durawalkie handsets. It slots into the handset battery bay and connects to the same BMS interface as the factory pack. Capacity figures come from the product data — 1800mAh / 6.66Wh.

• DuraFon platform compatibility: The 1x, 4x, Pro, and Durawalkie handsets share the same battery bay dimensions, connector pinout, and BMS handshake — that is why one pack covers all four. Swapping between models does not require any firmware or pairing change on the battery side.
• Bench tested on actual hardware: We cycled this pack on a DuraFon handset and confirmed the BMS accepted charge from the base station cradle on the first insertion. Voltage held at 3.7V nominal through multiple charge cycles with no cutoff errors logged.
• First charge after installation: Place the handset in the base station cradle immediately after fitting this battery and leave it for a full 16 hours before taking the handset off the base. Li-ion packs shipped in partial charge state need a complete slow charge to register accurate capacity with the handset fuel gauge.

Talk time shorter than expected in the first week after replacement

A fresh Li-ion pack often under-reports capacity for the first three to five charge cycles because the handset fuel gauge is still calibrating against the new cell. The gauge was tuned to the discharge curve of the old, worn pack — it needs a few full charge-discharge cycles to relearn. Do not judge the battery on the first two days. Run the handset down to the low-battery warning, return it to the base, and repeat this three to five times to let the gauge settle.

Base station charge light not activating after inserting handset

When a Li-ion pack has been in storage, its resting voltage can drop low enough that the base station charge circuit does not recognise it as a valid battery. The base looks for a voltage above a minimum acceptance threshold before starting the charge cycle. Remove the handset, wait 10 seconds, and re-seat it firmly — the cradle contacts sometimes need a clean connection to trigger the charge circuit. If the light still does not activate, check that the contacts on both the handset and the base are free of debris and that the resting voltage of the pack reads at least 3.0V with a multimeter before returning it.