About this replacement
Somfy CL32 Cord Lift / Sonesse 28 — 10.8V Li-ion Replacement Battery (9021217)
This is a 10.8V 2600mAh Li-ion battery for Somfy motorized window covering systems. It fits the CL32 Cord Lift, RU 30 Junior, Sonesse 28, TL25 Cord Lift, and three additional Somfy motor models sharing the same voltage rail and connector. When the original cell degrades, shades stop responding or move sluggishly — this battery restores full motor function without replacing the motor unit.
- CL32, Sonesse 28, and RU 30 platform compatibility: These Somfy motors share the same 10.8V three-cell Li-ion architecture, connector pinout, and BMS handshake protocol. Swapping between models in this family does not require firmware changes or hardware modification.
- Bench tested on actual hardware: We cycled this battery through repeated shade raise/lower sequences and monitored the BMS under motor-start load. The protection circuit held charge cutoff cleanly at full voltage and tripped correctly at the low-voltage threshold without nuisance trips mid-cycle.
- Post-install network re-join delay: Somfy motorized shades with wireless receivers perform a mesh network re-join sequence after any power interruption. After inserting this battery, wait 60 seconds before sending a command through your app or remote — triggering the motor before the receiver re-joins the network can cause a missed command that looks like a battery fault.
Why the CL32 drains faster after a battery swap than the original cell did
Somfy wireless motors poll their network channel at set intervals to stay responsive to app and remote commands. If your smart home hub or Somfy app has a high polling frequency configured, the receiver draws standby current more often than a lightly configured setup. A new battery at full 10.8V makes this more noticeable because the motor responds faster, confirming the radio is active. Check your Somfy app automation settings and reduce unnecessary scheduled triggers to lower standby draw.
Shade stops mid-travel and will not complete a full raise or lower
This symptom points to voltage sag under motor load rather than a dead battery. When a cell ages, its internal resistance rises and voltage drops sharply the moment the motor starts moving — the BMS reads this as a low-voltage fault and cuts power mid-cycle. A replacement cell at full 10.8V removes the sag and lets the motor complete its travel limits. If the issue persists with a new battery, check the motor's limit settings in the Somfy app, as an overset upper limit forces the motor to work against the tube and trigger an overload cutoff.