Ascom D81 Cordless Phone Replacement Battery 3.7V 1100mAh

Ascom D81 — 3.7V Li-ion Replacement Battery (660273/1B)

This 3.7V, 1100mAh lithium-ion battery replaces the original pack in the Ascom D81 cordless DECT handset. It fits the D81, DH5, DH5-AABAAA/2E, and related models sharing the same form factor and OEM part numbers 660273/1B and 1220187. Physical dimensions are 73.60 × 43.50 × 11.00mm — confirm these match your handset bay before ordering.

• D81 and DH5 platform fit: These handsets share a common battery bay, connector pinout, and charge management circuit. The same 3.7V cell and BMS handshake applies across D81, DH5, and DH5-AABAAA/2E variants — which is why one part number covers the group.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the D81 platform. The BMS accepted the full charge cycle without triggering protection cutoff, and voltage held steady across the operating range the handset draws during standby and active call states.
• First charge on the D81 base station: Seat the handset in the D81 base immediately after installing this battery and leave it for a full charge cycle before first use. Li-ion cells shipped at partial state of charge need a complete supervised charge to initialise the battery gauge correctly in this handset.

Talk time shorter than expected after fitting the new battery

A fresh Li-ion cell often reads lower capacity on the first few cycles because the handset's fuel gauge was calibrated to the old, degraded pack. The D81 recalibrates its charge tracking over two to three full charge-and-discharge cycles. Run the handset down to the low-battery indicator, then charge it fully — repeat this twice. By the third cycle, talk time should reflect the rated 1100mAh capacity.

Handset loses DECT pairing after battery replacement

Removing the battery from a DECT handset cuts power to the volatile memory that stores the base station subscription. The D81 can drop its pairing record when power is fully removed. To re-register, press and hold the pairing button on the base station until the indicator flashes, then initiate registration from the handset menu. The default system PIN on most Ascom bases is 0000.