GTE BT10 Cordless Phone Replacement Battery 3.6V 600mAh Ni-MH

Gte 21000 / 3150 Series — 3.6V Ni-MH Replacement Battery (BT10)

This is a 3.6V, 600mAh Ni-MH replacement battery for Gte cordless phone handsets. It fits the 21000, 3150, 31500, and 3260 models using the BT10 pack. When the original battery can no longer hold charge, this is the direct swap to get the handset working again.

• 21000 / 3150 / 31500 / 3260 handsets: These models all share the BT10 footprint — same three-cell Ni-MH configuration, same connector orientation, and same voltage rail the handset PCB expects. One pack covers all of them.
• Bench tested on actual hardware: We cycled this pack through charge and discharge on a Ni-MH compatible analyser. The BMS accepted charge without trip events, and cell balance held stable across three full cycles before rated capacity was confirmed.
• First charge after installation: Place the handset in the base for a full 16-hour charge before first use. Ni-MH cells in cordless phone packs arrive partially discharged from storage. Skipping the slow initial charge means the cells never reach rated capacity — and talk time stays short even after several shorter top-ups.

Talk time shorter than the original battery after replacement

Ni-MH cells don't reach full rated capacity on the first charge cycle. Capacity builds gradually over three to five full charge-discharge cycles — this is normal chemistry behaviour, not a fault. If talk time is short after the first day, run the handset until it drops out, then return it to the base for a full charge. Repeat this two more times and capacity should stabilise near the 600mAh rating.

Base station shows no charge or error light with new battery installed

Ni-MH packs that have sat in storage can drop below the voltage threshold the base station uses to detect a valid battery. The base sees a voltage too low to recognise as a chargeable pack and shows an error or simply does nothing. Remove the battery, let it sit in the handset off the base for two minutes, then re-seat the handset firmly in the cradle. If the base still won't initiate charging, confirm the handset contacts and base contacts are clean — oxidation on either side blocks the charge circuit before it starts.