UMI UMIDIGI X Replacement Battery 3.85V 3900mAh 1ICP5/68/83

UMI UMIDIGI X — 3.85V Li-Polymer Replacement Battery (1ICP5/68/83)

This is a 3900mAh Li-Polymer cell rated at 3.85V, replacing OEM part 1ICP5/68/83 in the UMIDIGI X smartphone. It fits the UMIDIGI X directly and matches the original cell's dimensions at 83.30 × 65.10 × 4.30mm. Capacity figures come from the product data — 15.02Wh total energy.

• UMIDIGI X fitment: The UMIDIGI X uses a dedicated battery bay sized for this exact cell footprint. The connector orientation and BMS handshake points match the OEM layout, so the fuel gauge IC on the motherboard can read cell state correctly without adapter modifications.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the UMIDIGI X platform and monitored BMS communication throughout. The protection circuit responded correctly to end-of-charge voltage and did not trip on normal screen-on current draw.
• First-cycle fuel gauge reset: On first use after installation, disable fast charging and run one full discharge-to-charge cycle at standard current. This lets the fuel gauge IC recalibrate its coulomb counter against the new cell's discharge curve before high-current charging loads an uncalibrated cell.

Why the UMIDIGI X reports wrong battery percentage after a cell swap

The UMIDIGI X uses a coulomb-counting fuel gauge IC that builds its charge model from the previous cell's history. When you install a new cell, that learned model no longer matches the actual discharge curve of the replacement. The IC continues to reference stale data until it observes a full discharge and charge cycle on the new cell. One complete cycle at standard charge rate — not fast charge — is enough to push the IC through recalibration and bring percentage readings back into alignment.

Sudden shutdown at 20–30% on the replacement cell

This happens when the fuel gauge IC still references the old cell's voltage-to-capacity curve, placing the estimated state of charge higher than the actual cell voltage. Under modem transmission load or screen brightness spikes, the new cell voltage drops below the BMS cutoff threshold — typically around 3.0V — before the OS registers a low-battery warning. The fix is the same recalibration cycle: drain the phone to automatic shutdown, then charge uninterrupted to 100% at the default charge rate. After that single cycle, the coulomb counter anchors to the new cell's actual voltage floor.