Simoco-Sepura STP8000 7.4V 3300mAh Replacement Battery

Simoco-Sepura Tetra STP8000 Series — 7.4V Li-ion Replacement Battery (STP8000)

This 7.4V 3300mAh Li-ion battery replaces the original pack in the Simoco-Sepura Tetra STP8000 and compatible STS8000, STP8038, and STP8030 series handheld radios. It delivers 24.42Wh of capacity through the same contact and BMS configuration as the factory pack. Suited to public safety, security, and enterprise field operations where maintaining radio availability matters.

• STP8000 series platform compatibility: The STP8000, STS8000, STP8038, and STP8030 share the same 7.4V rail, physical contact layout, and BMS handshake protocol — which is why a single replacement pack covers the full family without modification.
• Bench tested on actual hardware: We ran this pack through a full charge cycle and PTT-load test on STP8000 hardware. The BMS handled the transmit current spike without tripping into overcurrent protection, and the dock accepted the BMS handshake on first insertion after a contact wipe.
• First insertion on a Tetra 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 Tetra dock requires a clean contact cycle to complete the BMS handshake before charging begins.

Why the STP8000 cuts out mid-transmission on a new battery

A new Li-ion cell ships at storage voltage — typically around 3.7V per cell, or roughly 7.4V total. When PTT is pressed, the transmit current draw spikes sharply, and the BMS may interpret that surge as an overcurrent event if cell voltage is already near the lower end of the acceptable window. The radio drops off-air or falls to reduced TX power as a protective response. Charge the pack fully before first operational use — target 8.4V at the pack terminals — and the BMS will handle the transmit spike without cutoff.

Bar indicator showing one fewer bar than expected after fitting a new STP8000 pack

The Tetra STP8000 uses a voltage-threshold bar indicator — each bar represents a voltage band, not a chemically measured state of charge. A new pack fresh from storage sits at a mid-range voltage, so the indicator reads one or two bars below full even though the cell capacity is intact. This is not a fault with the pack. Place it in the dock for a complete charge cycle until the dock LED goes green, then check the indicator — it will read full at 8.4V pack voltage.