BST-22 Sony Ericsson T300 Replacement Battery 3.7V 1200mAh

Sony Ericsson T300 / T310 Series — 3.7V Li-ion Replacement Battery (BST-22)

This is a 3.7V, 1200mAh Li-ion replacement for the BST-22 battery. It fits the Sony Ericsson T300, T306, and T310 mobile phones. Capacity is 4.44Wh — matching the original cell specification.

• T300, T306, T310 platform fit: All three models use the same BST-22 footprint, voltage rail, and connector pinout. The BMS handshake on each device expects a 3.7V nominal cell — this replacement meets that requirement without modification.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the T310 platform. The BMS accepted the cell without fault codes, and protection circuits tripped correctly at the expected low-voltage cutoff threshold.
• Fuel gauge recalibration on first use: After fitting this battery, run one full discharge-to-charge cycle before relying on the percentage readout. The T300 series fuel gauge IC calibrates its curve against actual cell behaviour — skipping this step can cause the OS to report inaccurate percentages for several days.

Sudden shutdown at 20–30% on the T300 and T310

This happens when an aged cell can no longer hold voltage under load — the modem drawing current during a call or data event pulls the cell below the BMS cutoff threshold, even though the fuel gauge still shows charge remaining. A new BST-22 cell with a healthy internal resistance profile eliminates this voltage sag. After fitting the replacement, complete one full discharge cycle so the fuel gauge IC maps the new cell's actual discharge curve. Once calibrated, the percentage readout and shutdown behaviour should align correctly.

Phone won't power on after the battery sat in storage

Li-ion cells that drop below approximately 2.5V trigger a BMS lockout — the protection circuit disconnects the cell to prevent damage, and the phone shows no response when the power button is pressed. Connect the phone to a charger and leave it for 15–20 minutes without attempting to power it on. Most BST-22 compatible chargers deliver a trickle current that slowly recovers the cell voltage above the BMS re-enable threshold. Once the phone shows a charging indicator, allow a full charge cycle before use.