Vortex HD65Plus Replacement Battery GSP476386 3.85V 4800mAh

Vortex HD65Plus — 3.85V Li-Polymer Replacement Battery (GSP476386)

This is a 3.85V, 4800mAh (18.48Wh) Li-Polymer battery for the Vortex HD65Plus and HD65+. It replaces OEM part GSP476386. Fit this cell when the original no longer holds a charge or the phone shuts down unexpectedly under load.

• HD65Plus and HD65+ compatibility: Both model variants share the same battery bay dimensions (91.30 × 63.70 × 5.50mm), voltage rail, and connector pinout. The BMS handshake is identical across both, so one cell covers either variant without modification.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on the HD65Plus. The BMS accepted the cell without rejection flags, charge current stepped down correctly at 4.35V, and the protection circuit tripped as expected on a simulated over-discharge event.
• 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 the new cell's discharge curve before high-current charging starts. Skip this step and the coulomb counter will read against the old cell's curve, causing inaccurate percentage reporting from day one.

Sudden shutdown at 20–30% on the replacement cell

A new Li-Polymer cell has a steeper voltage cliff than a worn original — the phone's protection circuit cuts power before the percentage display reaches zero. The modem and display together draw enough current to pull cell voltage below the BMS cutoff threshold while the fuel gauge still shows charge remaining. After one or two full discharge-charge cycles, the gauge IC recalibrates against the actual cell curve and the shutdowns stop. If they continue past three cycles, check that the charge IC brought the cell to at least 4.34V before the phone disconnected from charge.

Phone warm near the battery during the first few charges

A new high-impedance cell dissipates more energy as heat during the first charge cycles than a broken-in cell does. The charge IC on the HD65Plus does not throttle current on the first cycle, so internal resistance in the fresh cell produces noticeable warmth near the battery bay. This is normal for the first two to three charges and fades as internal resistance drops. If the phone stays warm past the fifth full charge, measure charge voltage at termination — it should reach 4.35V and hold, not keep climbing.