Telstra T hub Cordless Phone Compatible Battery 3.7V 650mAh

Telstra T Hub — 3.7V Li-ion Replacement Battery

This 3.7V 650mAh Li-ion battery replaces the original cell inside the Telstra T Hub cordless handset. It fits the T Hub home phone system and restores full cordless operation when the existing battery no longer holds charge. Voltage and capacity match the original specification exactly.

• T Hub handset fit: The T Hub handset runs a single-cell Li-ion pack at 3.7V nominal. The BMS in the handset monitors cell voltage directly — a cell outside the accepted voltage window will trigger a charge fault or show no charge indication on the base. This battery sits within that acceptance range.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the bench. The BMS accepted the battery without error, charge current tapered correctly at top-of-charge, and the protection circuit tripped at the expected low-voltage cutoff threshold.
• First charge after installation: Place the handset in the base immediately after fitting this battery and leave it for a full uninterrupted charge before making calls. Li-ion cells shipped at partial state of charge need one complete charge cycle before the BMS calibrates the capacity gauge correctly.

Why the T Hub base shows a charging error with a new battery

Li-ion cells leave the warehouse at roughly 30–50% state of charge. If the cell voltage sits below the T Hub base station's acceptance threshold — typically around 3.0V — the base may display a charge error or flash the charge indicator abnormally. This is a voltage floor check, not a fault with the battery itself. Seating the handset in the base and leaving it undisturbed allows the charger to apply a low-current pre-charge until the cell climbs above the threshold, after which normal charging resumes automatically.

Handset not re-pairing with the base after battery replacement

Removing the battery cuts all power to the handset, which can wipe the DECT pairing registration stored in volatile memory. The handset will power on after charging but show no signal or fail to connect calls. To fix this, re-register the handset to the base using the pairing sequence — on the T Hub, hold the registration button on the base until the handset detects it, then confirm on the handset screen. Once registered, calls route normally.