EADS Cassidian TH1N Compatible Battery 3.7V 1550mAh BLN-10

EADS Cassidian TH1N — 3.7V Li-Polymer Replacement Battery (BLN-10)

This 3.7V, 1550mAh lithium-polymer pack replaces the OEM BLN-10, BLN-11, and HT9980AA batteries in the EADS Cassidian TH1N portable two-way radio. The TH1N is a slim-profile land mobile radio used by emergency services and professional field teams. Voltage and capacity figures are taken from the product data — 3.7V nominal, 5.74Wh.

• TH1N platform fit: The TH1N uses a flat Li-Polymer form factor — 74.50 x 52.10 x 6.70mm — with a specific contact arrangement that the BMS inside this pack must handshake with the radio's charge management circuit. All three OEM part numbers (BLN-10, BLN-11, HT9980AA) share this same physical and electrical interface.
• Bench tested on actual hardware: We cycled this pack through transmit load conditions on the TH1N platform and confirmed the BMS holds regulation through the current spike at PTT press — the point where most degraded packs sag and trigger low-voltage cutoff.
• First insertion on the TH1N charger dock: If the dock shows a fault LED on first insertion, remove the pack, wipe the gold contact strip with a dry cloth, and reseat firmly — the TH1N charger requires a clean contact cycle to accept the BMS handshake before it begins charging.

Why the TH1N cuts out mid-transmission on a freshly inserted pack

A new Li-Polymer cell ships at storage voltage — typically 3.6–3.7V — not at full charge. When PTT is pressed, transmit current spikes sharply, and if the cell hasn't completed at least one full charge cycle, the BMS may interpret the sag as an undervoltage fault and cut output. This is not a faulty pack. Fully charge the battery before the first transmission shift — the dock should show green before the radio goes into service. Once the cell is at full charge voltage (around 4.2V), the BMS handles transmit spikes without interruption.

Bar indicator showing one fewer bar than expected after a full charge

The TH1N's bar indicator reads voltage thresholds — it does not track charge state the way a smartphone does. A new cell has slightly different resting voltage characteristics than a conditioned one, so the indicator can read one bar low immediately after charge. Run one or two full charge-discharge cycles and the resting voltage will stabilise. After conditioning, check resting voltage at the contacts — it should read 4.1–4.2V off charger, which maps to a full indicator on the TH1N display.