Sennheiser EK2020 Receiver Compatible Battery 3.7V 1500mAh

Sennheiser EK2020 / EK 2020-D-II Receiver — 3.7V Li-Polymer Replacement Battery (543604)

This 3.7V 1500mAh Li-Polymer cell replaces the internal battery in the Sennheiser EK2020 and EK 2020-D-II wireless receiver units. It matches OEM part numbers 543604 and 19082102-1. Dimensions are 67.00 × 39.20 × 4.20mm — the flat profile fits the receiver's slim chassis without modification.

• EK2020 and EK 2020-D-II compatibility: Both receiver variants share the same battery bay geometry, connector pinout, and 3.7V supply rail. The BMS handshake is identical across the two, so one cell covers both units.
• Bench tested on actual hardware: We cycled this cell through the EK2020 receiver under active RF reception and DSP processing load. The BMS held cutoff voltage cleanly and did not trigger false low-battery warnings during the draw spike at RF lock-on.
• Contact cleaning before install: The EK2020 receiver uses a recessed flat-pack connector. Oxidation on the gold pads — even light discolouration — causes intermittent contact and receiver dropouts. Wipe the pads with isopropyl alcohol before fitting the new cell.

Receiver dropping signal mid-broadcast after battery swap

The EK2020 draws a combined load from the RF front-end and the audio DSP simultaneously. If the replacement cell has high internal resistance, voltage sags below the BMS protection threshold during that combined draw spike, triggering a momentary cutoff that reads as a signal drop. This is not a transmitter fault. Check the replacement cell's internal resistance — it should be under 150mΩ for stable operation at this load profile. A cell measuring above that threshold will sag on every RF lock-on event.

Receiver not re-syncing to transmitter after power loss

When the EK2020 loses power mid-session — either from a depleted cell or a BMS cutoff — the pairing data held in volatile memory is cleared on some firmware versions. The receiver comes back on but fails to lock onto the transmitter. This is not a fault with the new battery. Power on the transmitter first, then power on the receiver, and run a manual RF scan from the receiver menu to re-establish the link. Once re-paired on stable power, the sync persists across normal power cycles.