Asus Transformer Pad TF500T Replacement Battery 7.4V 3300mAh

Asus Transformer Pad TF500T — 7.4V Li-Polymer Replacement Battery (C21-TF500T)

This is a 7.4V, 3300mAh (24.42Wh) Li-Polymer replacement battery for the Asus Transformer Pad TF500T tablet. It fits the OEM slot directly and matches the original C21-TF500T specification. The connector, BMS handshake, and cell footprint are all matched to the TF500T mainboard.

• TF500T platform fit: The Transformer Pad TF500T uses a slim Li-Polymer cell with a specific connector pinout tied to the charge IC on the mainboard. This battery matches that pinout and the voltage rails the display, processor, and WiFi module draw from — keeping all three subsystems stable under combined load.
• Bench tested on actual hardware: We ran the C21-TF500T replacement through charge and discharge cycles on the TF500T platform. The BMS accepted the charge IC handshake on the first cycle, and voltage hold under simultaneous display-plus-WiFi load stayed within spec throughout testing.
• Fuel gauge recalibration after swap: After fitting this battery, run the tablet down to automatic shutoff, then charge it uninterrupted to 100% without using the device. This resets the fuel gauge IC calibration against the new cell and clears the inaccurate percentage readings that commonly appear after a battery replacement.

TF500T shutting down at 15–25% battery remaining

The TF500T pulls hardest when the display is at full brightness and WiFi is active — this combined load causes a rapid voltage drop as the cell approaches the lower end of its charge curve. If the fuel gauge IC was calibrated to an old, degraded cell, it underestimates how fast that voltage cliff arrives on a new cell with different discharge characteristics. The BMS trips a protective shutdown before the percentage indicator reaches zero. Run one full discharge-to-shutoff cycle followed by an uninterrupted charge to 100% — this re-anchors the fuel gauge to the new cell's actual voltage curve and resolves premature shutdowns.

Battery percentage jumping or reading incorrectly after replacement

The fuel gauge IC on the TF500T mainboard stores calibration data tied to the old cell's internal resistance and capacity profile. A new cell has a different profile, so the gauge reads inaccurately until it relearns the curve. You'll see jumps — the percentage may drop suddenly from 40% to 10%, or sit at 100% longer than expected, then fall fast. Fix this by discharging the tablet fully to automatic shutoff, then charging it continuously to 100% at least once without interruption. After that cycle, percentage readings stabilise.