For several years, we recommended protected Molicel 18650 cells from 18650 Battery Store (blue battery ≈ 71 mm length). Owl Sense battery clips were optimized around that slightly longer format.
Recently, those cells have been intermittently unavailable.
Why Length Is Important
Owl Sense battery clips are spaced for the longer 71 mm cells. If a shorter cell is installed without adjustment, the spring pressure is reduced. It will likely work fine but may cause undesirable issues.
In sensitive audio equipment, even small electrical inconsistencies can introduce noise artifacts. We have occasionally observed a clicking or beeping sound during SD write operations when battery contact is loose (visible in the spectrogram above). While this does not occur in every case, ensuring a firm battery connection helps prevent it. Please follow the steps below to restore proper clip tension.
Using the Shorter Batteries
Shorter cells can work well, but they do require a small adjustment.
- Remove the battery.
- Gently bend both battery clips inward.
- Use the middle of the clip as a visual reference for how much to bend.
- Reinstall the battery and confirm a firm, snug fit.
After you re-insert the battery, if you gently pull on the positive clip it should not easily disconnect from the cell.
As always, use protected 18650 cells, and ensure batteries fit snugly for best performance in the field.