About this replacement
Asus Fonepad 7 FE171MG — 3.8V Li-Polymer Replacement Battery (C11P1412)
This is a 3.8V 3900mAh Li-Polymer battery for the Asus Fonepad 7 FE171MG and related 7-inch Android tablet models. It replaces OEM part numbers C11P1412 and 0B200-01260000. Fit models include the FE175CG, FE170CG, and ME175CG series.
- FE171MG / ME175CG series fit: These models share a common battery bay size, connector pinout, and BMS handshake protocol — the C11P1412 cell services the entire group without modification or adapter.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the FE171MG. The BMS negotiated correctly with the charge IC, accepted full current from the outset, and reported state-of-charge without error after one calibration cycle.
- Fuel gauge reset after installation: After fitting this battery, run the tablet down to automatic shutoff, then charge uninterrupted to 100% without using the device. This resets the fuel gauge IC against the new cell's actual capacity curve and clears the inaccurate percentage readings that appear immediately after a swap.
Why the Fonepad 7 shuts down between 15–25% after a battery swap
The Fonepad 7 runs a combined load from its display, cellular radio, and Wi-Fi stack simultaneously. Under that combined draw, voltage drops faster than the fuel gauge IC predicts — because the IC is still calibrated to the old cell's discharge curve. The result is an abrupt shutdown that appears to happen at 15–25% remaining, even though the new cell has capacity left. One full discharge-to-shutoff cycle followed by an uninterrupted charge to 100% recalibrates the IC and eliminates these premature cutoffs.
Fast charging not available after fitting the C11P1412
The Fonepad 7's charge controller uses a handshake sequence to verify the connected cell before enabling higher charge rates. On a fresh battery swap, this handshake sometimes fails on the first cycle because the IC has no prior charge history for the new cell. The fix is straightforward: complete one full standard charge to 100% using the original Asus adapter. After that first accepted cycle, the controller recognises the cell and fast charge rates become available again on subsequent sessions.