Retevis RT-35 Two-Way Radio Replacement Battery 3.7V 900mAh

Retevis RT35 — 3.7V Li-ion Replacement Battery (RT-35)

This 3.7V Li-ion battery delivers 900mAh capacity for the Retevis RT35 two-way radio. It replaces the original pack when capacity fades after repeated charge cycles. The cell dimensions — 46.20 x 34.14 x 5.68mm — match the RT35 battery compartment exactly.

• RT35 platform fit: The RT35 runs a single-cell 3.7V Li-ion architecture. This pack shares the same voltage rail and connector footprint, so the radio's BMS accepts it without configuration changes.
• Bench tested on actual hardware: We ran this pack through transmit cycling on the RT35. The BMS handled the PTT current spike without triggering overcurrent lockout, and the radio held stable output through sustained keying.
• First insertion on the RT35 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 RT35 dock requires a clean contact cycle to complete the BMS handshake before charging begins.

Why the RT35 cuts out mid-transmission on a new battery

A new Li-ion cell ships at storage voltage — typically 3.6V to 3.7V, not full charge. When PTT is pressed, transmit current spikes sharply. If the cell is below roughly 3.5V at rest, that spike can pull the pack voltage under the BMS overcurrent threshold and trigger a cutout. This is not a fault with the radio or the battery. Charge the pack fully before the first transmission cycle and the cutout behaviour stops.

Bar indicator showing one fewer bar than expected after fitting this pack

The RT35 uses a voltage-threshold bar indicator — each bar corresponds to a voltage window, not a fuel gauge reading. A new pack at storage voltage sits in a lower threshold window, so the display shows one bar short of full even with a healthy cell inside. This is not a capacity fault. Run a full charge cycle first; once the cell reaches 4.2V the indicator moves to the correct position.