Yaesu SBR-28L FT-25R Replacement Battery 7.4V 1750mAh

Yaesu FT-25R / FT-65R Series — 7.4V Li-ion Replacement Battery (SBR-28L)

This is a 7.4V, 1750mAh Li-ion replacement battery for the Yaesu FT-25R, FT-65R, FTA-250L, FT-4XR, and four additional models that share the SBR-28L footprint. It slots into the same bay as the original pack and presents the same BMS handshake to the charger dock. Voltage and capacity match the OEM spec: 7.4V nominal, 12.95Wh.

• FT-25R / FT-65R platform compatibility: These models share a common battery bay geometry, contact rail spacing, and BMS communication protocol. The SBR-28L form factor was carried across the FTA-250L and FT-4XR lines for the same reason — Yaesu standardised the 7.4V Li-ion pack across its compact amateur handheld range to keep one charger dock compatible with multiple radios.
• Bench tested on actual hardware: We cycled this pack through transmit loads on the FT-25R platform. The BMS held cutoff cleanly at the lower voltage threshold during sustained PTT holds and recovered without lockout when the load was released. No overcurrent trip was triggered under standard 5W output draws.
• First insertion into the 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 SBR-28L BMS requires a clean contact cycle for the dock to register the pack's state-of-charge before charging begins.

Why the FT-25R cuts out mid-transmission on a fresh SBR-28L

A new Li-ion cell ships at storage voltage — typically 3.6–3.7V per cell, not the 4.2V full-charge ceiling. Under a 5W transmit load, that storage-state voltage can sag enough to trigger the radio's low-voltage cutoff before the BMS trips. The radio cuts TX, not because the pack is faulty, but because it hasn't been charged yet. Run a full charge cycle before the first field use. After a complete charge, transmit-state voltage holds well above the cutoff threshold under normal PTT duty cycles.

Bar indicator showing one fewer bar than expected after SBR-28L install

The FT-25R uses a voltage-threshold bar indicator — it reads resting cell voltage and maps it to a bar count. A pack at storage voltage reads lower than a fully charged pack, so the radio may show two or three bars instead of four immediately after installation. This is not a cell defect or capacity mismatch. Charge the pack fully in the dock, then power the radio on — resting voltage at full charge will push the indicator to its maximum bar count.