Southwestern Bell BP901 Cordless Phone Compatible Battery 3.6V 1500mAh

Southwestern Bell BP901 / BT901 — 3.6V Ni-MH Replacement Battery

This is a 3.6V 1500mAh Ni-MH battery for Southwestern Bell cordless phone handsets using the BP901 and BT901 designations. It restores talk and standby function to handsets where the original cell no longer holds a useful charge. Voltage and chemistry match the original pack exactly.

• BP901 and BT901 handset compatibility: Both model designations use the same 3.6V single-cell Ni-MH pack with the same connector and footprint. The base station charges the pack through the handset contacts, so the physical fit and voltage rail both need to match — this battery meets both requirements.
• Bench tested on actual hardware: We cycled this battery through a base station charge and discharge sequence. The cell accepted charge within the first 30 minutes and the BMS on the handset did not flag a fault. Voltage held steady across multiple talk events.
• First charge on NiMH cordless packs: After installing, seat the handset in the base and leave it for a full 16 hours before first use. NiMH cells shipped in a partially discharged state — a slow, full initial charge lets each cell in the pack reach rated capacity evenly. Skipping this step results in lower-than-rated capacity across early cycles.

Base station showing no charge or error light after installing a new pack

Southwestern Bell base stations use a voltage threshold to confirm a valid battery is present before starting the charge cycle. A new NiMH pack sitting in storage can drop below 3.0V, which puts it under the base acceptance threshold. The base reads this as no battery or a fault condition and refuses to charge. Place the handset in the base, wait 10–15 minutes — some bases will pulse a trickle charge to bring the cell up to ~3.2V before switching to normal charge mode. If the error light persists past 20 minutes, remove and reseat the handset to re-trigger the detection circuit.

Range drops noticeably when the battery is below half charge

DECT handsets regulate transmit power from the battery voltage rail. When a NiMH cell sags below roughly 3.4V under RF load, the handset's transmit output drops and range shrinks. This is more pronounced in the first few cycles before the pack is conditioned. Running three to five full charge-and-discharge cycles brings the cell to rated capacity and reduces voltage sag under load. If range is still short after five cycles, check that the handset contacts and base cradle pins are clean and making firm contact.