Sony PHA-3 Replacement Battery 3.7V 4900mAh LIS1570HNPC

Sony PHA-3 / PHA-3C — 3.7V Li-Polymer Replacement Battery (LIS1570HNPC)

This 3.7V, 4900mAh lithium-polymer cell replaces the original LIS1570HNPC battery in the Sony PHA-3 and PHA-3C portable headphone amplifiers. The PHA-3 runs a discrete amplifier circuit with a relatively high idle current, so cell capacity matters more here than in simpler portable devices. Dimensions are 90.00 × 63.80 × 6.00mm — measure your existing cell before ordering if the housing has been opened previously.

• PHA-3 and PHA-3C shared platform: Both models use the same battery bay, connector, and BMS handshake protocol. The PHA-3C is a China-market variant with identical internal hardware, so one cell fits both without modification.
• Bench tested on actual hardware: We cycled this cell through the PHA-3 BMS at multiple gain settings. The protection circuit tripped correctly at low-voltage cutoff, and charge acceptance held consistent across three full cycles with no capacity drop flagged by the onboard fuel gauge.
• First-cycle gain discipline: Run the amplifier at 50% volume for the first full charge cycle. Full-volume operation during initial use draws peak current from an uncalibrated cell and can trigger a premature BMS trip before the cell reaches its rated delivery capacity.

Amp shutting off before the battery indicator reaches empty

The PHA-3 amplifier circuit requires a minimum rail voltage higher than the display's low-battery cutoff threshold. When a degraded or newly installed uncalibrated cell sags under load, the amp shuts down even though the indicator still shows charge remaining. This is a voltage sag issue, not a fuel gauge fault. After two or three full charge-discharge cycles, the BMS recalibrates its state-of-charge mapping and the shutdowns stop — provided the cell itself is healthy.

Battery draining noticeably faster at high gain settings

Output power in the PHA-3 scales directly with gain — higher gain means the amplifier stage draws more current from the cell continuously, not just at peaks. At maximum gain, current draw can be two to three times the draw at low gain. This is normal circuit behaviour, not a battery fault. If drain feels excessive even at low gain, check that the cell resting voltage sits at or above 3.6V after a full charge — anything lower points to a cell that hasn't completed its initial calibration cycle.