Comrex Access Portable2 Replacement Battery 7.4V 7800mAh

Comrex Access Portable2 — 7.4V Li-ion 7800mAh Replacement Battery

This 7.4V, 7800mAh Li-ion battery replaces the internal cell in the Comrex Access Portable2 portable audio codec. The Access Portable2 is a field broadcast unit used for live audio transmission and remote reporting. It draws steady current during active codec processing and RF transmission, so cell capacity matters more here than in intermittent-use devices.

• Access Portable2 platform fit: The Access Portable2 runs a 7.4V two-cell Li-ion architecture tied directly to the codec board and transmission circuitry. Voltage tolerance on this platform is tight — a cell that sags below the BMS cutoff threshold mid-transmission will drop the link without warning.
• Bench tested on actual hardware: We cycled this cell under sustained codec-active and transmitting load. The BMS held charge acceptance cleanly across multiple cycles, and discharge curve stayed within the operating window through full depletion without false cutoffs.
• Field power management on the Access Portable2: When running this unit in IFB or contribution mode, avoid hot-swapping the battery mid-stream — the codec requires a clean boot sequence on power restoration to re-establish the transmission link correctly.

Why the Access Portable2 drops its transmission link before the battery indicator hits empty

The Access Portable2 does not use a simple voltage divider for its battery gauge. It maps remaining capacity against a discharge curve calibrated to the original factory cell. A replacement cell with a slightly different internal resistance profile will cause the BMS to read voltage drop as critically low before the actual cell charge is exhausted. The unit cuts transmission to protect the codec board. Running one full charge-discharge cycle after fitting the new cell lets the BMS recalibrate against the actual curve.

Access Portable2 powering on but immediately shutting down after battery replacement

This happens when the replacement cell ships in a low storage-state charge and the BMS reads the resting voltage as below the minimum boot threshold — typically under 6.0V on a 7.4V two-cell pack. The unit initiates a startup sequence, the codec board draws inrush current, voltage sags further, and the BMS trips. Connect the unit to the OEM charger before attempting to power on, allow it to charge to at least 7.2V, then boot normally.