Inmarsat Isatphone 2 Replacement Battery SAS2 3.7V 3000mAh

Inmarsat IsatPhone 2 — 3.7V Li-ion Replacement Battery (SAS2)

This is a 3.7V, 3000mAh (11.1Wh) Li-ion battery for the Inmarsat IsatPhone 2 satellite phone. It fits directly into the IsatPhone 2 battery bay and communicates with the phone's onboard BMS using the same protocol as the original pack. The IsatPhone 2 is a portable satellite communicator used for voice and messaging in areas with no cellular coverage.

• IsatPhone 2 fit: The IsatPhone 2 uses a single SKU battery platform across its production run — the SAS2 pack (also cross-referenced as 136081, VKB 56426 702 098, and VKB 56426 702 097). One connector pinout, one BMS handshake, no variation between units.
• Bench tested on actual hardware: We cycled this pack through satellite acquisition sequences on the IsatPhone 2. The BMS held stable through the antenna deployment current spike and sustained the transmit draw at full power without tripping into protection mode.
• Cold-field pre-use: In sub-zero conditions, keep this battery in an inner jacket pocket before powering on. Li-ion internal resistance climbs sharply below 0°C, and the current spike during satellite acquisition is enough to trip the BMS on a cold cell — leaving the phone dead before it ever locks onto a satellite.

Why the IsatPhone 2 shuts down during satellite acquisition

Satellite acquisition on the IsatPhone 2 is one of the highest-draw moments in the device's operation. The antenna deploys, the radio searches across the Inmarsat-I4 constellation, and transmit power ramps to maximum — all at once. An aged or cold battery can't sustain that current draw without its terminal voltage collapsing below the BMS cutoff threshold. The phone reads this as a depleted cell and shuts down, even when the charge indicator shows capacity remaining. A fresh pack with low internal resistance is the fix.

Charger not accepting the IsatPhone 2 battery after extended storage

If the IsatPhone 2 has sat unused for several months, the battery may self-discharge below the charger's acceptance voltage — typically around 2.5V for this cell chemistry. The IsatPhone 2 charger will show no activity or blink an error because the BMS blocks charge input on a cell it reads as critically low. Place the phone on charge for 30–60 minutes without interruption; the BMS uses a trickle pre-charge cycle to bring the cell back above 2.5V before switching to normal charge current. If the charger still shows no response after an hour, check the cell voltage directly — below 2.0V, recovery is unlikely.