Uniden 5105 Replacement Battery 3.6V 500mAh Ni-MH

Uniden 5105 / 5145 / LS5105 Series — 3.6V Ni-MH Replacement Battery (89-1333-01-00)

This is a 3.6V 500mAh Ni-MH battery for Uniden cordless phone handsets including the 5105, 5145, 5146, and LS5105. It replaces OEM part numbers 89-1333-01-00, BT5632, and BT5872. The battery mounts inside the handset and powers both talk and standby operation when the handset is off the base.

• 5105 / 5145 / LS5105 handset compatibility: These models share the same physical bay, three-cell Ni-MH configuration, and base-station charge contact layout — one battery fits the full group without modification.
• Bench tested on actual hardware: We ran the pack through a full charge cycle on the base station and confirmed the BMS accepted charge, the charge indicator cleared correctly, and voltage held at 3.6V nominal across load.
• First-charge cycle on the base station: After installing, seat the handset in the base for a full 16 hours before first use. Ni-MH cells in cordless phones ship partially discharged; the slow trickle charge from the base is what brings them to rated capacity — skipping this step means the first few cycles will fall short.

Talk time shorter than original battery after replacement

Ni-MH cells do not deliver full rated capacity on the first charge cycle — this is normal chemistry, not a faulty battery. The cells need three to five full charge-and-use cycles before the electrolyte is properly conditioned and capacity stabilises. Each cycle should run from a full base charge to natural handset cutoff, not a partial discharge. By cycle four or five, talk time should reflect the rated 500mAh output.

Base station showing no charge light or error after new battery install

Cordless phone base stations check incoming voltage before starting a charge cycle — if the pack has dropped too low in storage, the base may not recognise it and will withhold charging. Uniden bases typically expect to see at least 2.4V at the contacts to initiate a cycle. If the charge light stays off, remove the battery, wait 30 seconds, reinsert, and reseat the handset firmly — this resets the contact handshake. If the base still won't charge, a brief top-up from a compatible external Ni-MH charger at 3.6V will bring the pack above the acceptance threshold.