Wiko Rakuten Hand TPJ21J11P Replacement Battery 3.85V 2600mAh

Wiko Rakuten Hand — 3.85V Li-Polymer Replacement Battery (TPJ21J11P)

This is a 3.85V, 2600mAh (10.01Wh) Li-Polymer cell for the Rakuten Hand smartphone, including the TD-LTE JP and P710 variants. It slots into the same bay as the original TPJ21J11P and connects to the same charge IC and fuel gauge circuitry. If the original cell is swelling, dropping off charge quickly, or causing unexpected shutdowns, this is the direct swap.

• Rakuten Hand / P710 platform fit: The Rakuten Hand, Rakuten Hand TD-LTE JP, and P710 all share the same battery bay dimensions and connector pinout. The BMS on this cell communicates with the same charge IC across those variants, so voltage regulation and charge termination work correctly on all three.
• Bench tested on actual hardware: We ran this cell through charge and discharge on the Rakuten Hand platform. The BMS accepted handshake from the charge IC without triggering a fault, and charge termination cut off cleanly at full voltage without overrun.
• Fuel gauge recalibration on first use: After fitting this cell, disable fast charging and run one full discharge-to-charge cycle at standard current. The fuel gauge IC on the Rakuten Hand is calibrated to the old cell's discharge curve — one slow cycle lets it remap against the new cell before high-current charging begins.

Why the Rakuten Hand shuts down suddenly at 20–30% after a cell swap

This happens because the fuel gauge IC still holds the discharge curve from the old, degraded cell. When the new cell hits a load spike — modem transmission, screen wake, or GPS — voltage drops faster than the gauge expects, and the phone interprets that as a critical low-voltage event. The processor cuts power before the gauge registers the real state of charge. One full slow discharge-charge cycle forces the coulomb counter to rebuild its model against the new cell's actual voltage curve, and the shutdowns stop.

USB fast charge not activating on the first cycle after replacement

On the first charge after installation, the charge IC may not negotiate fast charge protocols with the new BMS — the controller defaults to standard 5V/1A input until it confirms the cell is within expected parameters. This is a deliberate protection behaviour, not a fault with the battery or the charger. Let the first charge complete at standard current. On the second cycle, the charge IC recognises the cell state and USB-PD or proprietary fast charge negotiation proceeds normally. If fast charge still does not activate after two full cycles, check the USB port for debris and confirm the charger outputs at least 18W.