Ascom 21 Satellite Phone Replacement Battery 7.4V 1400mAh

Ascom 21 — 7.4V Li-ion Replacement Battery (TH-01-006)

This 7.4V, 1400mAh Li-ion battery fits the Ascom 21 satellite phone. It replaces OEM part numbers TH-01-006 and CP0119. The Ascom 21 operates on satellite networks for voice and messaging in areas with no cellular coverage — the battery supports that full communication load.

• Ascom 21 fit: The Ascom 21 uses a dedicated 7.4V two-cell Li-ion pack with a BMS that handshakes with the phone's charge controller. This replacement matches that voltage rail and connector configuration. Swapping a mismatched pack will trigger a charge rejection at the host port.
• Bench tested on actual hardware: We ran this pack through satellite acquisition cycles, which draw sharp current spikes as the antenna locks onto a constellation. The BMS held cutoff thresholds correctly across repeated acquisition attempts and sustained transmit loads at full power.
• Cold-field storage tip: In sub-zero conditions, keep this battery in an inner jacket pocket before use. Li-ion internal resistance rises sharply below 0°C, and the satellite acquisition current spike can trip the BMS on a cold cell before the phone ever connects to a satellite.

Ascom 21 shutting down during satellite acquisition

Satellite acquisition on the Ascom 21 pulls a sharp, sustained current spike as the radio module scans and locks onto a satellite. This momentary high-draw event stresses the BMS more than a steady voice call does. If the cell voltage dips under load — particularly in cold conditions or on an aged pack — the BMS trips the output to protect the cells. The fix is a fresh pack at full charge, above 8.2V open-circuit, before heading into the field.

Charger not accepting the battery after extended storage

Li-ion cells that sit discharged for weeks can drop below the charger's acceptance threshold — typically around 2.5V per cell, or roughly 5.0V for the full 7.4V pack. Most chargers see this as a fault condition and refuse to initiate a charge cycle. To recover the pack, use a charger with a trickle or recovery mode that can push a low precharge current until the cells climb back above the acceptance floor. Once the pack reads above 6.0V, a standard charge cycle will complete normally.