Retekess HR-11s Replacement Battery 3.7V 1200mAh Li-ion

Retekess HR-11s / V115 — 3.7V Li-ion Replacement Battery

This 3.7V, 1200mAh Li-ion cell replaces the original battery in the Retekess HR-11s and V115 wireless tour guide receivers. These are compact audio receiver units — not smartphones — used in guided tours and group presentations. The cell matches the original voltage and capacity at 4.44Wh, and fits within the 53.00 × 33.90 × 5.70mm envelope of the battery bay.

• HR-11s and V115 platform fit: Both units run on the same 3.7V single-cell architecture with the same physical footprint, so they share this battery. The BMS protection circuit handles over-discharge cutoff and charge termination the same way across both models.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge passes on the HR-11s receiver. The BMS protection tripped correctly at the low-voltage threshold, and charge termination occurred cleanly at 4.2V without thermal runaway.
• First-use recalibration on the HR-11s: After fitting a new cell, run one complete discharge to low-battery shutoff, then charge fully without interruption. The receiver's fuel gauge IC was calibrated to the old cell's discharge curve — this single cycle resets it against the new cell so the indicator reads accurately.

Why the HR-11s battery indicator reads full but shuts off early

The HR-11s uses a simple fuel gauge IC that maps voltage to a percentage based on the discharge curve of the original cell. A new cell has a slightly different curve, so the gauge reads higher than the actual state of charge. The device then hits the BMS low-voltage cutoff before the indicator reaches zero. One full discharge-charge cycle after installation re-anchors the IC to the new cell's actual curve and eliminates premature shutoffs.

Battery not charging after the receiver sat unused in storage

If the HR-11s sat discharged for weeks or months, the cell may have dropped below 2.5V — the BMS protection floor. At that level the BMS locks out normal charge current to protect the cell. Plug the receiver into a USB charger and leave it connected for 20–30 minutes without powering it on; the charger trickle-feeds current through the protection circuit at a safe rate. If the charge LED does not respond after 45 minutes, measure cell voltage directly — anything below 2.0V indicates an unrecoverable cell and the battery needs replacement.