Ericsson DT390 Replacement Battery BKB201010/1 3.7V 650mAh

Ericsson DT390 — 3.7V Li-ion Replacement Battery (BKB201010/1)

This is a 3.7V, 650mAh lithium-ion battery for the Ericsson DT390 cordless DECT handset. It replaces OEM part numbers BKB201010/1, FA01302005, and FA83601195. The DT390 is a business-grade DECT phone — this battery slots directly into the handset compartment and connects to the same BMS interface as the factory cell.

• DT390 handset fitment: The DT390 uses a slim single-cell Li-ion pack at 3.7V nominal. The base station charges via a contact pad on the handset cradle, and the BMS inside the battery manages cutoff voltage so the base charger circuit sees the correct charge acceptance signal.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the DT390 platform. The BMS held cutoff at the correct thresholds and the base station registered a clean charge state without error codes throughout testing.
• First-charge protocol for the DT390: After fitting the new battery, seat the handset in the base cradle and leave it for a full uninterrupted charge cycle before making calls. Li-ion cells shipped in storage state need one complete charge to calibrate the BMS fuel gauge to the DT390's charge controller.

Talk time shorter than expected after fitting the new battery

A new Li-ion cell shipped from storage may not hit full rated capacity on the first cycle. The BMS fuel gauge in the DT390 calibrates itself against actual charge and discharge data — it takes two to three full cycles before the reading stabilises. If talk time is still short after three full charge and discharge cycles, check that the handset contacts and base cradle contacts are clean and making firm connection. Dirty contacts cause trickle charging instead of a full charge current, leaving the cell partially filled.

Base station showing no charge or refusing to charge the new battery

A Li-ion cell sitting in storage can drop below the base station's minimum charge acceptance voltage. The DT390 base charger circuit checks cell voltage before applying charge current — if the cell reads too low, the base treats it as a fault and will not begin charging. Remove the battery, wait 30 seconds, refit it firmly, and reseat the handset in the cradle. If the base still shows no charge, measure the battery terminal voltage with a multimeter — a healthy Li-ion cell should read at least 3.0V at rest before the base will accept it.