About this replacement
Sennheiser Momentum In-Ear / Présence — 3.7V Li-Polymer Replacement Battery (BA 170)
This 3.7V, 120mAh lithium-polymer cell replaces the OEM battery in the Sennheiser Momentum In-Ear and Présence wireless earbuds. Part number BA 170 (also listed as AHB471233PST) is the individual earbud cell — not a charging case pack. Capacity figure comes from our product data: 120mAh (0.44Wh).
- Momentum In-Ear and Présence compatibility: Both models share the same earbud housing geometry, connector pinout, and BMS handshake protocol, which is why a single cell covers both lines. Swapping a cell from one model to the other works because the charge management IC reads the same cell chemistry and voltage range.
- Bench tested on actual hardware: We cycled this cell through a full charge-discharge sequence on the Momentum In-Ear earbud. The BMS accepted the cell without error flags, balanced charging initiated correctly, and the protection circuit tripped cleanly at the rated cutoff voltage.
- First-cycle base station requirement: After fitting a new cell, seat the earbud in the charging cradle and let it complete one full charge cycle before use. The base station logs the new cell during this cycle — skipping it causes the talk-time indicator to report inaccurate figures for several days.
Why the Présence earbud cuts out mid-call after a cell replacement
The Présence draws power simultaneously from the audio amplifier and the DECT radio transmitter. That combined load briefly spikes current demand well above what a degraded or partially charged cell can deliver. A fresh cell at storage voltage — around 3.6V — may still trigger the BMS undervoltage cutoff under this spike. One full charge cycle in the base station brings the cell to 4.2V and eliminates the sag threshold issue.
Base station shows full charge but earbud shuts off after a few seconds
This happens when the replacement cell arrives at storage voltage and the base station's charge detection circuit misreads it as already full. The cell never receives a proper charge cycle, so it holds just enough voltage to power on but collapses under audio load. Force a full reset by removing the earbud from the cradle for 30 seconds, then reseating it — the base should then detect the cell correctly and begin charging from 3.6V up to 4.2V.