PROTEAR AB/S1 Bluetooth Earmuff Compatible Battery 3.7V 1100mAh

PROTEAR Bluetooth-Headphones Earmuff — 3.7V Li-Polymer Replacement Battery (AB/S1)

This 3.7V, 1100mAh Li-Polymer cell replaces the original AB/S1 battery inside the PROTEAR Bluetooth earmuff headphones, including the Ear Defenders and AM/FM Radio Bluetooth variants. It restores wireless audio and radio playback when the original cell no longer holds a usable charge. Dimensions are 46.30 × 32.50 × 10.00mm — confirm your cell matches before fitting.

• Earmuff platform fit: The PROTEAR earmuff range — Bluetooth, Ear Defenders, and AM/FM Radio Bluetooth — all draw from the same 3.7V Li-Polymer cell with the AB/S1 part number. The BMS on these units expects a nominal 3.7V input; fitting a mismatched cell trips the protection circuit and the headphones will not power on.
• Bench tested on actual hardware: We cycled this cell through combined Bluetooth audio and radio draw and confirmed the BMS accepted the pack without a protection fault. Charge termination occurred correctly at 4.2V with no thermal event.
• First-cycle charge on the PROTEAR earmuff: These headphones use the charge cycle to calibrate their onboard fuel gauge. Run the first full charge to 4.2V via the original cable before using Bluetooth — skipping this step causes the indicator to misread state of charge from the first session onward.

Audio cutting out mid-playback on a freshly fitted AB/S1 cell

The PROTEAR earmuff combines a Bluetooth radio and an AM/FM tuner in a compact housing. When both run simultaneously, instantaneous current draw spikes above the cell's resting output. If the replacement cell shipped at storage voltage — typically around 3.6V — the BMS interprets this spike as an undervoltage condition and shuts the output rail. Charge the cell fully to 4.2V before first use. After one complete charge cycle the BMS threshold is met under combined load and cutouts stop.

Talk time noticeably shorter than rated across the first few sessions

Li-Polymer cells in low-draw headset applications do not reach full rated capacity on cycle one. Internal resistance is slightly elevated from storage, and the electrode surface area is not fully active until the cell has been charged and discharged three to five times. Capacity steps up incrementally across those early cycles — this is normal cell behaviour, not a fault with the replacement pack. Run three full charge-discharge cycles at normal listening volume before comparing against the rated 1100mAh figure.