Cassidian TPH700 Replacement Battery 7.4V 1800mAh HR7742AAA02

Cassidian TPH700 / P3G — 7.4V Li-ion Replacement Battery (HR7742AAA02)

This 7.4V 1800mAh Li-ion battery replaces the OEM pack in the Cassidian TPH700 and P3G portable radios. It fits the same dock and connector footprint as the original HR7742AAA02 and HR7742AAB02 packs. Capacity figure is taken directly from product data — 13.32Wh at the rated 7.4V nominal.

• TPH700 and P3G shared platform: Both radios run the same 7.4V two-cell Li-ion architecture, the same dock connector pinout, and the same BMS handshake protocol — which is why one battery part number covers both models. Swapping between the two does not require a firmware or dock change.
• Bench tested on actual hardware: We cycled this pack through a full charge and PTT-load discharge on a TPH700 body. The BMS held the 7.4V rail steady through repeated transmit bursts and triggered low-voltage cutoff cleanly at the correct threshold — no false trips during the transmit current spike.
• First insertion into the TPH700 dock: New cells ship at storage voltage, typically around 3.7–3.8V per cell. 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 TPH700 dock requires a clean contact cycle to recognise the BMS before the charge cycle starts.

Why the TPH700 cuts out mid-transmission on a new battery

The TPH700 draws a short, sharp current spike the moment PTT is pressed — this is normal transmit behaviour on any land mobile radio. If the BMS has not completed its first full charge cycle, the cell voltage sits lower than the BMS expects under that spike, and it reads the draw as an overcurrent event. The BMS then trips the pack off to protect the cells, killing the transmission. One full charge cycle from the dock resolves this — the BMS recalibrates its overcurrent threshold once it knows the cell's actual capacity.

Bar indicator on TPH700 showing fewer bars than expected after fitting new pack

The TPH700 uses a voltage-threshold bar indicator — each bar corresponds to a voltage band, not a fuel gauge reading. A new cell at storage voltage (around 3.7V per cell, 7.4V pack total) sits at or near the midpoint of the indicator range, so the radio may show two bars instead of four. This is the cell's storage charge state, not a capacity fault. Charge the pack fully in the dock until the charge LED goes green — the indicator will read at the correct level once the pack reaches 8.2–8.4V.