BenQ T60 Replacement Battery 3.7V 550mAh Li-ion

BenQ T60 / 228 — 3.7V Li-ion Replacement Battery

This is a 3.7V 550mAh Li-ion cell for the BenQ T60 and 228 candybar mobile phones. It slots into the original battery bay and connects to the same three-contact terminal. Capacity matches the factory spec at 550mAh (2.04Wh).

• T60 and 228 shared platform: Both models run on the same baseband hardware and draw from an identical battery bay geometry, connector pitch, and voltage rail. One cell covers both.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on a T60 unit. The BMS accepted the charge profile without fault flags, and voltage held above 3.5V through the discharge curve until the low-voltage cutoff triggered cleanly.
• Fuel gauge recalibration on first cycle: After fitting this cell, run one full discharge to auto-off, then charge uninterrupted to 100% before normal use. The T60's fuel gauge IC was calibrated to the original cell's discharge curve — skipping this step causes the percentage counter to read from stale data and show inaccurate figures.

Sudden shutdown at 20–30% on the BenQ T60

Early 2000s candybar phones like the T60 use a simple fuel gauge IC with no active coulomb counter. When an aged or new uncalibrated cell hits a voltage cliff — typically around 3.6V under the load of an active call or backlight — the IC interprets it as a valid low-voltage cutoff and shuts the phone down, even though the reported percentage still shows 20–30%. This is not a cell fault. It means the fuel gauge has not yet mapped the new cell's actual discharge curve. Run one complete discharge cycle to auto-off, then charge fully. After that cycle, the IC tracks voltage more accurately and the early shutdowns stop.

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

Li-ion cells stored without charge self-discharge below 2.5V per cell over time. At that level, the BMS locks out to prevent damage to the chemistry. The T60 will show no sign of life — no boot screen, no charging indicator. Connect to a charger and leave it for 15–20 minutes before pressing the power button. Most BMS circuits on cells at this voltage level need a trickle pre-charge phase to recover to 2.9V before they release the lockout and allow normal charging current to flow.