Lenovo Ideatab Miix 3 L14C1P21 Compatible Battery 3.7V 4200mAh

Lenovo Ideatab Miix 3 — 3.7V Li-Polymer Replacement Battery (L14C1P21)

This is a 3.7V, 4200mAh (15.54Wh) Li-Polymer battery for the Lenovo Ideatab Miix 3 and Miix3-830 tablet. It replaces OEM part L14C1P21, which sits inside the non-removable tablet assembly. The Miix 3 is a detachable hybrid — it runs as both a standalone tablet and a laptop when docked to its keyboard base.

• Miix 3 and Miix3-830 compatibility: Both the Miix 3 and Miix3-830 draw from the same 3.7V cell with the L14C1P21 part number. The connector pinout, BMS handshake protocol, and physical dimensions — 133.50 × 72.40 × 3.20 mm — are identical across both variants. No adapter or modification is needed.
• Bench tested on actual hardware: We ran L14C1P21 replacements through charge and discharge cycles on a Miix 3 unit. The BMS accepted the new cell without throwing a fault code, and the charge IC reached a full-state cutoff correctly at 4.2V.
• Fuel gauge recalibration after swap: After installing this battery, run the tablet down to automatic shutoff — do not force-power it off — then charge uninterrupted to 100%. That single full cycle lets the fuel gauge IC map its cutoff thresholds against the new cell and clears the inaccurate percentage readings that appear immediately after a swap.

Miix 3 shutting down at 15–25% remaining after battery replacement

This shutdown happens because the fuel gauge IC is still calibrated to the old cell's voltage curve. The new cell's voltage drops steeply under combined display and Wi-Fi load around that 15–25% window, and the IC interprets it as a critical-low event. It triggers a forced shutdown even though usable charge remains. One complete discharge-to-shutoff followed by an uninterrupted charge to 100% resets the calibration and moves the cutoff threshold to the correct voltage floor.

Fast charging not resuming after a battery swap on the Miix 3

The Miix 3 charge controller uses a negotiation handshake with the charger on the first accepted charge cycle after a new cell is installed. Until that cycle completes, the device defaults to a lower current draw as a protective fallback. This can look like fast charge has stopped working. Plug in the original Lenovo charger, let the tablet complete one full charge from below 10% to 100% without interruption, and the charge IC will re-enable the higher current rate on the next session.