Sena SMH-10 Lifespan Replacement Battery 3.7V 500mAh

Sena SMH-10 / SMH-10 Lifespan — 3.7V Li-Polymer Replacement Battery (1ICP52/248P 1S1P)

This 3.7V 500mAh Li-Polymer cell replaces the original pack in the Sena SMH-10 and SMH-10 Lifespan helmet communication systems. It fits the slim housing on both variants without modification. Dimensions are 51.82 x 21.72 x 5.00mm — measure your existing cell before ordering if you are unsure which variant you have.

• SMH-10 and SMH-10 Lifespan compatibility: Both models run the same 3.7V single-cell architecture with identical connector pinout and BMS handshake protocol. The shared voltage rail means one cell fits both — no firmware difference affects charging behaviour.
• Bench tested on actual hardware: We cycled this cell through the SMH-10 charging circuit and monitored BMS communication. The protection board negotiated charge termination correctly and the unit reported battery status accurately in the Bluetooth status indicator.
• First-cycle charging on the SMH-10: Seat the headset in the clamp charger and run a full charge cycle before taking your first call. The SMH-10 logs the new cell during that cycle — skip it and the talk-time estimate shown via voice prompt will read low until the unit calibrates.

Why the SMH-10 cuts out mid-call on a new battery

The SMH-10 draws from both the Bluetooth audio stack and the intercom radio simultaneously during active calls. That combined load can pull the cell voltage below the BMS cutoff threshold if the cell has not yet completed two or three full charge-discharge cycles. A new Li-Polymer cell ships at storage voltage — around 3.8V — and its usable window narrows until it is conditioned. If the headset drops out mid-call in the first few uses, run two or three full cycles through the clamp charger before diagnosing a faulty cell.

Headset shows full charge but cuts off after a few minutes of use

This happens when the cell arrives at storage voltage and the SMH-10's fuel gauge has not yet mapped the actual charge curve of the new pack. The unit reads voltage at rest — which looks healthy — but sags under load faster than the gauge predicts. It is not a fault with the cell. Charge fully via the clamp charger, use the headset until it powers down naturally, then charge again. By the third cycle the voltage-to-capacity mapping stabilises and cutoffs stop occurring early. Confirm the cell is reaching 4.2V at charge termination before concluding otherwise.