GP T188 Cordless Phone Replacement Battery 3.6V 1200mAh

GP T188 / T340 — 3.6V Ni-MH Replacement Battery (T188, T340)

This GP battery is a 3.6V, 1200mAh Ni-MH pack that fits Siemens Gigaset cordless handsets using the T188 or T340 battery format. It restores talk time and standby capacity when the original cell has degraded. Voltage and connector match the Gigaset charging circuit directly.

• T188 and T340 handset compatibility: Both OEM part numbers share the same 3.6V single-cell Ni-MH format, the same footprint, and the same two-contact connector used on the Gigaset base charging rail. One replacement covers both variants.
• Bench tested on actual hardware: We cycled this pack on a Gigaset base station and confirmed the BMS accepted charge from the first dock, held voltage through a full discharge curve, and showed no false-empty cutoff at mid-cycle.
• First charge on Gigaset handsets: After installing, seat the handset in the base and leave it for a full 16 hours before first use. Ni-MH cells shipped in a partial state need a slow first charge to reach their rated 1200mAh — skipping this shortens capacity on every cycle that follows.

Base station showing no charge light after fitting a new Ni-MH pack

Gigaset base stations check incoming cell voltage before starting the charge cycle. A Ni-MH battery stored for several months can drop below 3.0V, which the base reads as a fault rather than a flat cell. The fix is to bridge-charge the pack briefly with a compatible external Ni-MH charger until voltage climbs above 3.2V. Once voltage recovers, re-seat the handset in the base and the charge indicator returns to normal.

Talk time noticeably shorter than the original battery after replacement

New Ni-MH cells need three to five full charge-discharge cycles before they deliver rated capacity — this is normal, not a fault. On cycles one and two, available capacity typically sits 20–30% below the 1200mAh figure. Each full cycle conditions the cell chemistry and recovers more headroom. By cycle five, measured discharge should reach or exceed the original battery's end-of-life output.