Ascom i75 Cordless Phone Replacement Battery 3.7V 700mAh

Ascom i75 / Talker 9D24 Series — 3.7V Li-ion Replacement Battery (653081)

This is a 3.7V, 700mAh Li-ion replacement battery for the Ascom i75 and Talker 9D24 series DECT handsets. It fits the 9D24-FAADA, 9D24-FBADA, and related Talker 9D24 MKI variants. Physical dimensions are 59.10 × 41.60 × 14.50mm — check these against your existing pack before ordering.

• i75 and Talker 9D24 platform fit: These handsets share the same battery bay dimensions, connector pinout, and 3.7V supply rail. The BMS communication protocol is consistent across the 9D24-FAADA and 9D24-FBADA variants, so one replacement battery covers the full model range listed.
• Bench tested on actual hardware: We cycled this battery through charge and discharge on the i75 platform. The BMS accepted the cell without fault codes, reported state-of-charge correctly on the handset display, and held the 3.7V nominal rail under DECT RF transmit load.
• First charge on the i75 base station: After fitting this battery, seat the handset in the Ascom i75 base and leave it for a full charge cycle before placing it into active use. Li-ion cells shipped in storage state need one complete base-station charge to calibrate the fuel gauge to the new cell's actual capacity.

Talk time shorter than expected on the i75 after battery swap

The i75 fuel gauge calibrates against the original cell's charge history stored in the BMS. When a new battery goes in, that history is blank and the gauge underestimates remaining capacity for the first few cycles. Run the handset through two or three full charge-and-use cycles on the base station. Capacity readings stabilise once the BMS has logged enough full cycles to map the new cell accurately.

Ascom i75 base station shows no charge or error light after new battery fitted

Li-ion cells can drop to a low resting voltage during extended storage — some below the threshold the Ascom base station accepts as a valid battery. The base will not begin a normal charge cycle if it reads the pack as too depleted. Remove the handset, reseat it firmly so the contacts are clean and fully engaged, then check the charging indicator again within two minutes. If the error persists, the cell voltage has likely dropped below 3.0V and the base may need to trickle-charge the pack for up to 30 minutes before the normal charge cycle starts.