About this replacement
Leagoo T1 Plus — 3.8V Li-Polymer Replacement Battery
This is a 3.8V, 3250mAh Li-Polymer replacement battery for the Leagoo T1 Plus smartphone. It slots into the phone where the original cell has degraded through repeated charge cycles. Voltage and capacity match the stock specification — 3.8V nominal, 12.35Wh total.
- T1 Plus cell format: The T1 Plus uses a Li-Polymer pouch cell at 3.8V nominal with a matching connector and BMS pinout. Swapping chemistry or voltage on this platform trips the charge IC and prevents a full charge cycle from completing.
- Bench tested on actual hardware: We ran the cell through a full discharge-charge cycle on the bench. The BMS handshake completed correctly, charge current ramped to CC phase without interruption, and the cell reached 4.35V cutoff at termination.
- Fuel gauge recalibration after install: On first use after installation, disable fast charging and run one complete discharge-charge cycle down to auto-shutdown and back to 100%. This lets the fuel gauge IC map the new cell's actual discharge curve before the coulomb counter locks in percentage readings.
Sudden shutdown at 20–30% on the T1 Plus after a cell swap
A new cell has a slightly different voltage-to-capacity curve than the original. The fuel gauge IC still references the old curve, so it reads 25% remaining when the actual cell voltage has already dropped below what the modem and display need to stay powered. The phone sees a valid percentage on screen but cuts out because the hardware voltage rail collapses under load. One full calibration cycle — drain to shutdown, charge uninterrupted to 100% — rewrites the curve the gauge uses and stops the early cutoff.
USB fast charge not engaging on the first cycle after replacement
When a new cell first connects, the BMS reports a high internal impedance state until it completes one charge cycle. Some charge ICs on the T1 Plus interpret this as an unsafe cell condition and drop back to standard 5V/1A input rather than negotiating the fast-charge protocol. This is not a fault with the replacement cell. Charge once at standard speed to full, then disconnect and reconnect — the BMS impedance reading drops and fast charge negotiation succeeds on the next plug-in.