Sony Ericsson Xperia ray SO-01C Compatible Battery 3.7V 1000mAh

NTT DoCoMo SO-01C / SO-05D — 3.7V Li-ion Replacement Battery

This is a 3.7V, 1000mAh Li-ion cell for the Sony Ericsson Xperia ray (SO-01C) and SO-05D — compact NTT DoCoMo Android smartphones. It fits the original battery bay directly and connects to the same charge IC and fuel gauge circuit. Capacity is rated at 3.7Wh, matching the original specification.

• SO-01C and SO-05D compatibility: Both models share the same 48.00 × 47.50 × 5.10mm cell format and 3.7V nominal voltage rail. The connector orientation and BMS handshake are identical across these two variants, so one cell covers both.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the SO-01C platform. The BMS accepted charge current without interruption, and the fuel gauge IC tracked state of charge without cutoff errors across the full discharge curve.
• Fuel gauge recalibration on first use: After installation, run one complete discharge to automatic shutdown, then charge to 100% uninterrupted. The SO-01C fuel gauge IC calibrates its coulomb counter against the new cell's discharge curve during this first cycle — skipping it causes the percentage indicator to read inaccurately for days.

Sudden shutdown at 20–30% on the Xperia ray after a cell swap

The Xperia ray's modem and display draw peak current simultaneously during calls or screen-on events. A new cell with an uncalibrated fuel gauge IC can report 25% remaining while actual cell voltage has already dropped below the BMS cutoff threshold under that load spike. The BMS trips, and the phone shuts down without warning. One full discharge-charge cycle recalibrates the coulomb counter and eliminates the mismatch between reported and actual charge state.

Phone shows wrong battery percentage after replacement

The SO-01C stores the previous cell's discharge curve in the fuel gauge IC's memory. When a new cell goes in, that stored curve no longer matches the new cell's voltage profile, so the percentage reading drifts — often reading 80% when the phone is nearly flat. This is not a faulty cell. Discharge the phone fully until it powers off automatically, then charge it to 100% in one session without interruption. After that single cycle, the fuel gauge resets its reference points to the new cell and percentage accuracy returns.