About this replacement
Tether Tools Air Direct — 7.4V Li-ion Replacement Battery
This 7.4V 1800mAh Li-ion cell replaces the internal battery in the Tether Tools Air Direct wireless tethering unit. The Air Direct mounts to a camera hot shoe or rig and handles live image transmission to a laptop or tablet on set. Keeping a spare cell charged means a dead battery does not interrupt a tethered shoot.
- Air Direct platform fit: The Air Direct runs a 7.4V two-cell Li-ion pack with a specific connector footprint and BMS communication line. This cell matches that voltage rail and physical format so the unit powers on and communicates normally with the host camera body.
- Bench tested on actual hardware: We ran this cell in an Air Direct unit connected to a Canon EOS body over a tethered USB-C session. The BMS accepted the cell on first install, charge state reported correctly, and the wireless link held through the full draw cycle.
- First-charge protocol for Air Direct cells: Charge this cell fully via the Air Direct unit before your first shooting session. The Air Direct's onboard BMS maps the battery-remaining indicator against a full-charge baseline — skipping this step can cause the indicator to read low even when capacity is present.
Why the Air Direct drops its wireless link near the end of a charge cycle
The Air Direct's Wi-Fi or USB-C transmission module draws a short burst of current each time it syncs a full-resolution RAW file. As cell voltage drops toward the lower cutoff threshold, those bursts can pull voltage below the BMS trip point momentarily. The unit resets the wireless link to protect the cell rather than push through. If you see repeated disconnects late in a session, the cell is close to flat — swap it before the next shot sequence rather than waiting for a full shutdown.
Air Direct showing a lower charge percentage than expected after a partial charge
The Air Direct maps its battery indicator against the discharge curve of the original cell. A new replacement cell may have a slightly different voltage-to-capacity curve at mid-charge, causing the display to read lower than actual state of charge. Run two full charge and discharge cycles through the unit and the BMS will recalibrate its threshold mapping. After that, the indicator should track the cell accurately from 100% down to the low-voltage cutoff near 6.0V.