Alcatel Mobile 300 DECT Replacement Battery 3.7V 800mAh

Alcatel Mobile 300 / 400 DECT Series — 3.7V Li-ion Replacement Battery (3BN66305AAAA000828)

This 3.7V 800mAh Li-ion battery fits the Alcatel Mobile 300 DECT, Mobile 400 DECT, Mobile Reflexes 300, and Mobile Reflexes 400 cordless handsets. It replaces OEM part numbers 3BN66305AAAA000828, ALCH-011664AC, and 3BN66305AAAA000846. Physical dimensions are 51.23 x 37.90 x 11.28mm — confirm fit before installing.

• Mobile 300 and 400 DECT platform: These models share a common battery bay dimensions, connector pinout, and BMS handshake protocol, which is why one cell covers the full range. The Li-ion protection circuit communicates charge state to the base station the same way across both series.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on a DECT handset test rig. The BMS held the correct 3.7V nominal rail, cut off cleanly at the low-voltage threshold, and accepted charge current from a standard Alcatel base station without triggering a fault condition.
• First-charge protocol for DECT handsets: After fitting this battery, seat the handset in the base and leave it undisturbed for a full 16 hours before making the first call. Li-ion cells shipped in partial-charge storage state need a complete first cycle to let the BMS calibrate its capacity gauge accurately.

Range drops when the handset moves away from the base after a battery swap

DECT transmitters draw a short burst of higher current each time the handset pings the base. If the battery voltage sags under that RF load, the handset reduces transmit power to protect the cell. This makes range feel shorter than it was on the original battery — even if capacity reads fine at idle. The fix is completing two or three full charge-discharge cycles so the BMS stabilises the voltage curve under load. After that, the transmit power burst is sustained properly and range returns to normal.

Handset loses its pairing to the base after fitting the replacement battery

Removing the old battery cuts power entirely to the handset's volatile memory, which some Alcatel DECT models use to store the pairing registration. When the new battery goes in, the handset boots with no stored base ID and shows an unregistered status. This is not a battery fault — it is expected behaviour after a full power loss. Re-register the handset using the base station's registration button and the handset menu; the process takes under two minutes and restores normal operation.