Harman/Kardon Esquire Mini P655252 Replacement Battery 3.7V

Harman/Kardon Esquire Mini — 3.7V Li-Polymer Replacement Battery (P655252)

This 3.7V, 2100mAh Li-Polymer battery replaces part number P655252 in the Harman/Kardon Esquire Mini portable Bluetooth speaker. It restores the speaker's ability to run without a power cable. Dimensions are 50.15 × 49.16 × 6.90mm — measure your original cell before fitting.

• Esquire Mini platform fit: The Esquire Mini uses a slim pouch-cell format to fit inside its compact fabric enclosure. This cell matches the original connector orientation, protection circuit, and cell footprint so the BMS handshake completes on first charge.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the Esquire Mini mainboard. The protection circuit tripped correctly at low-voltage cutoff and the charge IC accepted the cell without fault codes.
• Fuel gauge recalibration after fitting: After replacing the battery, run the Esquire Mini down until it powers off on its own, then charge it uninterrupted to 100%. This gives the speaker's fuel gauge circuit an accurate full-cycle reference and prevents false "full" readings that cause early shutdowns.

Why the Esquire Mini reads full charge but cuts out during playback

The Esquire Mini's onboard fuel gauge tracks charge state by counting coulombs, not by measuring terminal voltage directly. When the battery has aged or been replaced, the gauge's stored reference points no longer match the actual cell capacity, so it reports a full charge well before the cell is truly topped off. Under amplifier load — especially at higher volumes — the cell voltage sags below the BMS cutoff threshold faster than the gauge predicts. The speaker then shuts down while the display still shows charge remaining. One full discharge-to-cutoff and uninterrupted recharge cycle resets the reference and aligns the gauge to the new cell.

Audio distorting before the battery indicator reaches empty

As the Li-Polymer cell discharges toward the lower end of its voltage curve, internal resistance rises and the terminal voltage sags under amplifier draw. The Esquire Mini's Class D amplifier clips when supply voltage drops below the threshold it needs to swing the output stage cleanly, producing distortion before the protection circuit has triggered a shutdown. This happens earlier in a degraded or deeply discharged cell because internal resistance is higher from the start. If distortion appears consistently at the same apparent charge level, check terminal voltage with a multimeter — a resting reading below 3.5V on a supposedly charged cell confirms the cell needs replacement.