V Tech VT9109 Replacement Battery 3.6V 600mAh Ni-MH

V Tech VT9109 / VT9110 / VT9117 / VT9118 Series — 3.6V Ni-MH Replacement Battery

This is a 3.6V, 600mAh Ni-MH rechargeable battery for V Tech cordless phone handsets. It fits the VT9109, VT9110, VT9117, and VT9118, along with six additional models in the same series. It replaces the original cell when the handset no longer holds a charge through a normal call or standby period.

• VT9100-series handset compatibility: These models share the same 3.6V three-cell NiMH pack format, connector pitch, and physical footprint. The base station charging circuit on all of them is calibrated to the same charge termination voltage, so one battery spec covers the full range.
• Bench tested on actual hardware: We cycled this pack through charge and discharge on the VT9109 platform. The BMS accepted charge from the base station on the first insertion, and the handset registered full signal bars within a completed charge cycle.
• First-charge conditioning on NiMH cordless packs: After installing, seat the handset in the base for a full 16 hours before first use. NiMH cells in phone batteries ship partially discharged. Skipping the slow initial charge leaves usable capacity on the table for the first several cycles.

Base station charging error on a freshly installed NiMH pack

A new NiMH battery that has been sitting in storage can drop to a voltage the base station's charge controller reads as a fault condition. Most V Tech base stations use delta-V detection, which expects the cell voltage to climb from a baseline. If the pack is too flat, the controller sees no valid starting point and flags an error. Remove the handset, hold the battery contacts together with a known-good AA cell briefly to provide a surface charge, then reseat the handset. That small voltage bump is usually enough for the base to begin a normal charge cycle.

Range drops noticeably mid-call after a battery swap

This happens when the NiMH pack voltage sags under the RF transmit load before the cells have completed conditioning. The DECT radio in the VT9109 series draws a sharp current spike during transmission, and an unconditioned battery cannot hold its voltage steady under that load. The handset responds by reducing transmit power, which cuts effective range. Run three to five full charge-and-use cycles and the cells will firm up — internal resistance drops as the chemistry stabilises, and the voltage sag during transmit narrows. By cycle five, check that open-circuit voltage sits at or above 4.1V after a full charge.