About this replacement
Panasonic WX-CT2050 / Attune Aio 2050 — 3.7V Li-ion Replacement Battery (WX-C2050BAT)
This 3.7V, 1700mAh Li-ion battery replaces the original WX-C2050BAT pack in Panasonic wireless headsets used across office and call centre environments. It fits the WX-CT2050, Attune Aio 2050, WX-CH2050, and Ultraplex II 2051. Swap it in when the original cell no longer holds charge through a full shift.
- WX-CT2050 / WX-CH2050 / Ultraplex II 2051 platform: These headsets share the same 3.7V single-cell architecture, physical form factor, and BMS communication protocol with the base station — which is why one cell (WX-C2050BAT) covers the entire lineup. The connector pinout and charge termination voltage are identical across all four models.
- Bench tested on actual hardware: We ran this pack through a full charge cycle in a WX-CH2050 base station and confirmed BMS handshake, clean charge termination at 4.2V, and no fault codes on the base station display. Cell temperature stayed within normal range throughout the charge cycle.
- First-cycle base station logging: On first use, seat the headset in the base station and let it complete a full uninterrupted charge before taking any calls. DECT headsets log the new cell during this cycle — skipping it causes the base to report inaccurate charge status until the cycle completes.
Base station not recognising the new pack after swap
The WX-CT2050 base station communicates with the headset's BMS before it begins charging. If the base shows a charging error or no charge indicator after a battery swap, the BMS handshake has not completed. This usually happens when the new cell ships at storage voltage — around 3.6–3.7V — which sits below the threshold the base expects at the start of a fresh charge cycle. Reseat the headset firmly, leave it undisturbed in the cradle for at least 15 minutes, and the base should initiate the charge sequence normally.
Headset cuts out mid-call even with a charged battery
The WX-CT2050 draws on two loads simultaneously during a call — the audio codec and the DECT radio transmitter. Under that combined draw, a degraded or partially conditioned cell can sag below the headset's low-voltage cutoff threshold even when the indicator shows charge remaining. This is not a defective battery — it is a voltage-sag trip triggered by a cell that has not yet completed its conditioning cycles. Run three to five full charge and discharge cycles through normal use, and the cutoff trips should stop as the cell reaches its rated capacity at 3.7V nominal.