Simultalk 24G SBC EB4870 Replacement Battery 4.8V 700mAh

Simultalk 24G / SLT2400 — 4.8V Ni-MH Replacement Battery (SBC EB4870)

This is a 4.8V, 700mAh Ni-MH replacement battery for the Simultalk 24G and SLT2400 two-way radios. It replaces the OEM pack SBC EB4870 directly. Voltage, connector, and physical dimensions match the original at 44.00 × 41.00 × 10.50mm.

• 24G and SLT2400 fitment: Both models share the same battery bay dimensions, contact layout, and 4.8V power rail. One pack covers both platforms without modification.
• Bench tested on actual hardware: We cycled this pack through charge and transmit load sequences. The BMS handled the PTT current spike without tripping, and the charger dock accepted the handshake on a clean contact insertion.
• Contact strip condition on first insertion: If the charger dock shows a fault LED on first insertion, remove the pack, wipe the gold contact strip with a dry cloth, and reseat firmly. The Simultalk dock requires a clean contact cycle to complete the BMS handshake before charging begins.

Why the Simultalk 24G cuts out mid-transmission on a new SBC EB4870 pack

New Ni-MH cells ship at storage voltage, typically 1.1–1.15V per cell, which puts a fresh 4.8V four-cell pack around 4.4–4.6V at rest. When PTT is pressed, transmit current draws that voltage down sharply. If the pack has not completed at least one full charge cycle, that sag can cross the radio's undervoltage cutoff threshold and drop the transmission. Run one complete charge cycle before field use. After that first cycle, the cells hold their resting voltage above 4.8V and the sag stays within the radio's operating window.

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

The Simultalk 24G uses a voltage-threshold bar indicator — each bar maps to a specific voltage band. A new pack sitting at storage voltage reads lower than a fully charged one, so the radio displays one fewer bar even though the cell capacity is intact. This is not a fault with the pack. Charge the battery fully and allow the charger to complete its cycle. At full charge, resting voltage should read approximately 5.5–5.6V across the four-cell pack, and the bar indicator will reflect that correctly.