HTC Desire S Replacement Battery BA S530 3.7V 1350mAh

HTC Desire S / S510E / Saga — 3.7V Li-ion Replacement Battery (BA S530)

This is a 3.7V, 1350mAh Li-ion cell that replaces the original battery in the HTC Desire S, S510E, Saga, and PG88100 smartphones. It matches the OEM BA S530 footprint and connector, so it seats without modification. If your Desire S is shutting down early or refusing to hold a charge, this is the direct swap.

• Desire S platform compatibility: The S510E, Saga, and PG88100 all run on the same hardware platform as the Desire S — same 3.7V battery bay, same connector pinout, and the same charge IC expecting a single Li-ion cell. One cell fits the full lineup.
• Bench tested on actual hardware: We ran this cell through the HTC charge IC and confirmed BMS communication across charge and discharge cycles. The protection circuit tripped correctly at low-voltage cutoff, and charge termination fired at the expected 4.2V ceiling.
• Fuel gauge recalibration on first use: After fitting this cell, run one full discharge down to auto-shutoff, then charge uninterrupted to 100% before normal use. The Desire S fuel gauge IC calibrates its coulomb counter against that first complete cycle — skip it and percentage readings will drift.

Sudden shutdown at 20–30% on the Desire S after a cell swap

This is a voltage cliff problem, not a capacity problem. The Desire S fuel gauge IC was calibrated to the discharge curve of the original, aged cell — often one that sagged badly under load. When the modem fires a data burst or the screen peaks brightness, current draw spikes and the new cell's voltage drops momentarily below the IC's cutoff threshold, triggering an emergency shutdown even though the cell still has capacity remaining. The fix is a full discharge-charge cycle so the fuel gauge rewrites its internal curve to match the new cell. After one complete cycle, the shutdowns stop.

Phone won't power on after the battery sat in storage for months

Li-ion cells self-discharge in storage. If this battery dropped below roughly 2.5V per cell while sitting unused, the built-in protection circuit locks out to prevent damage — and the phone reads this as a completely dead, unresponsive device. Plug directly into a wall charger rather than a USB port; wall chargers deliver enough initial current to nudge the BMS out of lockout. Leave it connected for 15–20 minutes before pressing the power button — at that point the cell should be above 3.0V and the phone will boot normally.