Prestigio Grace S5 Replacement Battery 3.7V 1550mAh

Prestigio Grace S5 — 3.7V Li-ion Replacement Battery (PSP5551 DUO)

This is a 3.7V, 1550mAh lithium-ion replacement battery for the Prestigio Grace S5 smartphone (model PSP5551 DUO). It slots into the original battery bay and restores power to a phone that no longer holds a charge or fails to turn on. Capacity is 5.74Wh — matching the original cell specification.

• Grace S5 / PSP5551 DUO fitment: Both the Grace S5 and the PSP5551 DUO share the same battery bay dimensions, connector orientation, and 3.7V nominal voltage rail — which is why one cell covers both identifiers. The BMS communicates with the phone's charge IC over the same two-pin thermistor line used in the original pack.
• Bench tested on actual hardware: We ran this cell through a full charge and discharge cycle on a Grace S5 unit. The BMS accepted charge handshake without fault codes, and charge IC current tapered correctly at the top-of-charge threshold.
• Fuel gauge recalibration on first use: After fitting this cell, disable any fast-charging mode and run one complete discharge-charge cycle at standard current. The Grace S5's fuel gauge IC was calibrated to the original cell's discharge curve — one full cycle against the new cell lets it relearn the voltage-to-capacity map before high-current charging begins.

Sudden shutdown at 20–30% on the Grace S5 after a cell swap

This is a voltage cliff problem, not a capacity problem. The Grace S5's modem and display draw a combined load spike that the fuel gauge IC cannot predict on an uncalibrated cell. When the new cell's voltage drops faster than the stored discharge curve expects, the phone interprets it as a critical low-voltage event and cuts out — even though the reported percentage reads 20–30%. One full discharge to automatic shutdown followed by an uninterrupted charge to 100% recalibrates the coulomb counter and moves the cutoff point back to its correct threshold.

Phone warm near the battery during first charge after replacement

A new high-impedance cell generates more heat per cycle than a broken-in cell at the same charge current. The Grace S5's charge IC does not reduce current on the first cycle — it runs at the full programmed rate regardless. This is normal during the first one or two cycles as internal resistance drops. If the phone stays warm beyond the second full charge cycle, check that the battery connector is fully seated — a partial connection forces the charge IC to compensate with higher voltage, which increases heat further. Reseat the connector and confirm the locking tab clicks before charging again.