ZTE Blade V40S Li-Polymer Replacement Battery 3.87V 4400mAh

ZTE Blade V40S / Axon 40 SE — 3.87V Li-Polymer Replacement Battery (Li3844T45P8h896546)

This is a 3.87V, 4400mAh (17.03Wh) Li-Polymer cell built to replace the original battery in the ZTE Blade V40S and Axon 40 SE. Both devices share the same battery bay dimensions and connector, making this a direct fit across the two models. Install it when the original cell no longer holds voltage under load or has physically swollen.

• Blade V40S and Axon 40 SE compatibility: Both handsets run the same 3.87V power rail, use an identical dock connector pinout, and accept the same BMS handshake from the Li3844T45P8h896546 cell. One SKU covers both models without any hardware modification.
• Bench tested on actual hardware: We ran this cell through charge, discharge, and fast-charge negotiation cycles. The BMS reported state-of-health correctly to the OS and accepted USB-PD handshake without rejection or thermal flag.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC map its coulomb counter to the new cell's discharge curve before high-current charging pushes energy into an uncalibrated reference baseline.

Sudden shutdown at 20–30% on a replacement cell

A new cell has a steeper voltage cliff than the aged cell it replaced. The fuel gauge IC still uses the old cell's curve, so it reports 25% remaining while the actual terminal voltage has already dropped below the safe cutoff threshold. Under modem or display load, current draw spikes and the BMS trips the output before the OS can react. One full slow discharge down to automatic shutdown, followed by a full charge, resets the coulomb counter and aligns the reported percentage with the new cell's actual curve.

USB-PD fast charge not working on the first cycle after replacement

On the first charge after a cell swap, the charge IC may refuse fast-charge negotiation because the BMS registers the new cell as an unknown state — cell impedance reads high on a fully discharged fresh cell and the protection circuit defaults to a slow pre-charge trickle below 3.0V per cell. Once the cell clears 3.0V, the BMS signals the charge IC that fast-charge parameters are safe to apply. Plug in, let the phone charge uninterrupted past the first 10–15 minutes, and fast charging will engage at that point without any further action.