Beats Studio Buds Charging Case Replacement Battery 3.8V 400mAh

Beats Studio Buds Charging Case — 3.8V Li-Polymer Replacement Battery (AEC701346)

This is a 3.8V, 400mAh lithium-polymer cell that replaces the internal battery in the Beats Studio Buds charging case. It fits the case directly, restoring its ability to recharge the Studio Buds earbuds away from AC power. When the original cell degrades, the case loses the capacity to top up the buds even once — swapping this cell brings the case back to full function.

• Studio Buds case fit: The case uses a single flat Li-Polymer cell at 3.8V nominal. The AEC701346 matches the original cell's voltage, footprint (45.00 × 12.50 × 6.80mm), and connector orientation — the case charging circuit does not require a BMS handshake to begin charging the buds.
• Bench tested on actual hardware: We cycled this cell through the Studio Buds case charging circuit and confirmed stable current draw at the case's internal charge management IC. Voltage held flat through multiple bud charge passes before dropping off at end-of-cell capacity.
• First-cycle case conditioning: After installation, run the case down completely with the buds inside before returning it to the charging cable. The case fuel gauge recalibrates on the first full drain-to-charge cycle — skipping this makes the LED indicator inaccurate from the start.

Why the Studio Buds case LED shows full but the buds die after one charge pass

The case stores a 400mAh reserve at 3.8V — enough to recharge the buds multiple times from a fully depleted state. When the internal cell degrades, its actual capacity drops well below that rating, but the case LED still reads green based on resting voltage rather than measured capacity. The buds pull a fixed charge current from the case; if the cell can't sustain that draw, the buds receive a partial charge before the case voltage collapses. A new cell at full 400mAh restores the full charge-pass count the case was built to deliver.

Case not charging the buds at all after battery replacement

If the case shows no activity after swapping the cell, the most common cause is a seating issue with the cell connector — a partially connected ribbon or pogo contact interrupts the circuit before the charge IC sees any input voltage. Remove and reseat the cell connector, then place the case on its charging cable for at least 30 minutes before testing. If the case charge IC has no cell voltage above approximately 3.0V on first contact, it may hold off output to the bud pads as a protection state. Confirm the case reads at least 3.2V at the charge input before expecting the buds to draw current.