HiFiMAN R2R2000 Compatible Battery 3.7V 1700mAh AEC103550

HiFiMAN R2R2000 — 3.7V Li-Polymer Replacement Battery (AEC103550)

This 3.7V, 1700mAh lithium-polymer cell replaces the original AEC103550 battery inside the HiFiMAN R2R2000 portable amplifier. It restores the unit's ability to drive high-impedance headphones away from a wall outlet. Dimensions are 49.20 × 33.50 × 10.20mm — measure your existing cell before ordering if you are unsure.

• R2R2000 cell matching: The R2R2000 runs a discrete R-2R ladder DAC stage alongside its amplifier circuit — both draw from the same cell. A cell with mismatched internal resistance will sag under that combined load, producing audible distortion before the battery gauge moves. AEC103550 specifies the correct impedance profile for this dual-load architecture.
• Bench tested on actual hardware: We cycled this cell through the R2R2000's charge circuit and confirmed the BMS accepted the cell without a protection-trip fault. Charge termination occurred cleanly at 4.2V with no thermal anomaly.
• First-cycle current draw on the R2R2000: Run the amplifier at 50% volume for the first full charge cycle. Full-volume operation on an uncalibrated cell draws peak current from both the DAC and amp stages simultaneously — this can trigger a premature BMS cutoff before the cell reaches its rated 1700mAh delivery capacity.

Amp shutting off before the battery indicator reaches empty

The R2R2000's protection circuit cuts power when cell voltage drops below its minimum threshold — this floor sits higher than the display's empty indicator. When a degraded cell sags quickly under load, the amplifier trips that voltage floor while the gauge still shows charge remaining. A fresh cell holds voltage flat longer under the combined DAC and output stage current draw. If shutdown happens repeatedly on a new cell, verify charge termination voltage reached 4.2V on the previous cycle.

Clipping and distortion at moderate volume on a new battery

Clipping at moderate listening levels on a freshly installed cell usually points to voltage sag, not gain or source issues. The R2R2000's output stage needs a stable rail — if the cell's internal resistance is elevated, instantaneous current demand during transient peaks pulls the rail voltage down, and the amp clips before it runs out of headroom on paper. This is most obvious on low-impedance headphones that pull more current per watt. Charge the cell fully to 4.2V, then retest at the same volume setting.