Lectrosonics LB-50 Replacement Battery 3.7V 750mAh Li-ion

Lectrosonics SSM Transmitters / IFBR1B Receiver — 3.7V Li-ion Replacement Battery (LB-50)

This is a 3.7V, 750mAh (2.78Wh) Li-ion replacement for the Lectrosonics LB-50 battery. It fits the SSM Bodypack Transmitter, SSM Micro Transmitter, and IFBR1B Receiver — compact wireless audio devices used in professional broadcast and live production. Voltage and form factor match the original cell exactly at 40.26 x 35.24 x 6.50mm.

• SSM and IFBR1B compatibility: These devices share the LB-50 footprint and the same 3.7V single-cell architecture. The BMS on each unit communicates charge state over the same contact arrangement, so this replacement cell integrates without modification or re-pairing the transmitter-receiver link.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on SSM-class hardware. The BMS accepted the cell without fault flags, voltage held stable under combined RF transmit and DSP load, and charge termination triggered cleanly at full capacity.
• Contact condition before fitting: On SSM bodypacks used in heavy production, sweat and handling residue build up on the battery contacts. A corroded contact creates a resistive joint — the BMS reads a false low-voltage state even on a fresh cell. Clean the contacts with isopropyl alcohol before fitting the new battery.

Transmitter dropping signal mid-broadcast on a new battery

The SSM transmitter draws current simultaneously from the RF stage and the DSP processing block. Under that combined load, a cell with elevated internal resistance — even a new one that sat in storage too long — can sag below the BMS cutoff threshold momentarily, triggering a shutdown. This appears as a clean signal drop with no warning on the receiver. Check the open-circuit voltage of the replacement cell before fitting: it should read 3.6–3.7V. A cell reading below 3.5V off the shelf has likely self-discharged past its recoverable range.

Receiver not syncing after swapping the transmitter battery

Cutting power to the SSM transmitter during a session can cause the transmitter to lose its stored RF channel and group settings on some firmware versions. When power is restored with the new cell, the transmitter broadcasts on a default or reset frequency that the IFBR1B receiver is not tuned to — so sync never completes. The fix is straightforward: after fitting the new battery, cycle the transmitter power and manually re-initiate the sync sequence from the receiver side. Confirm the transmitter's frequency group matches the receiver before going live.