About this replacement
Honor 90 Pro — 3.9V Li-Polymer Replacement Battery (HB506590EHW)
This is a 4900mAh 3.9V lithium-polymer cell for the Honor 90 Pro smartphone. It replaces the original HB506590EHW pack when the existing cell has degraded, lost capacity, or stopped holding a charge. Capacity is rated at 19.11Wh.
- Honor 90 Pro fit: The 90 Pro uses a dedicated battery bay sized for an 88.80 × 64.30 × 4.90mm cell. This replacement matches that footprint exactly, and the connector and BMS handshake align with the charge IC on the 90 Pro's mainboard.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the 90 Pro platform. The BMS communicated correctly with the device's fuel gauge IC, and charge termination triggered at the correct cut-off voltage without error flags.
- 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 recalibrate against the new cell's discharge curve before high-current charging pushes current into an uncalibrated cell.
Why the Honor 90 Pro reports wrong battery percentage after a cell swap
The 90 Pro uses a coulomb counter that builds its discharge model against the original cell's impedance profile. When a new cell goes in, that model is stale — the IC is measuring against a curve that no longer matches. This causes the percentage display to read high or low by a significant margin, especially in the mid-range. One full uninterrupted discharge-to-low, then a full charge, forces the IC to rewrite its reference table. After that cycle, percentage accuracy normalises.
Sudden shutdown at 20–30% on the replacement cell
A new lithium-polymer cell at rest can hold a nominal voltage that satisfies the fuel gauge, but under the combined load of the modem, display, and CPU, the cell's internal resistance causes a voltage sag that drops below the BMS protection threshold instantly. The system cuts power before the percentage counter catches up — so the phone appears to shut off with charge remaining. This is most common on the first few cycles before the cell's internal resistance settles. Run two or three full cycles and the voltage sag narrows; shutdowns at 20–30% typically stop once the cell stabilises above 3.5V under load.