About this replacement
Sony Xperia 10 III 5G — 3.85V Li-Polymer Replacement Battery (SNYSAC5)
This 3.85V, 4400mAh Li-Polymer cell replaces the SNYSAC5 battery in the Sony Xperia 10 III 5G and its regional variants — A102SO, PDX-213, and SOG04. It matches the original cell's dimensions (74.30 x 60.00 x 5.36mm), voltage rail, and connector footprint. Capacity is rated at 16.94Wh, matching the factory specification.
- Xperia 10 III variant coverage: The A102SO, PDX-213, and SOG04 are regional SKUs for the same hardware platform — same PCB layout, same battery bay, same BMS handshake protocol. One cell fits all three without modification.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the Xperia 10 III platform. The BMS accepted the cell on first connection, protection thresholds triggered correctly at the low-voltage cutoff, and the charge IC communicated without fault codes.
- First-cycle fast charge hold-off: 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 fast charging pushes current into an uncalibrated cell.
Sudden shutdown at 20–30% on the replacement cell
The Xperia 10 III's fuel gauge IC stores a learned discharge curve from the old cell. After a cell swap, that stored curve no longer matches the new cell's actual voltage-versus-capacity profile. When the modem fires during a 5G handoff or the display peaks in brightness, the new cell's voltage drops below the BMS cutoff threshold — even though the OS gauge still reads 20–30%. Run one full discharge to below 5% and a full charge to 100% without interruption. After that cycle, the coulomb counter resets its reference and the shutdowns stop.
USB-PD fast charge not activating after a cell swap
On some units, the charge IC will not negotiate USB-PD fast charging on the first cycle with a new cell — it defaults to standard 5V charging as a safety measure while the BMS builds a charge history. This is normal behaviour, not a fault with the cell or the charger. Plug in using the original Sony charger and cable, let the first full charge complete at standard rate, then unplug and replug. USB-PD negotiation typically activates from the second cycle onward.