Topcom Twintalker 7100 Compatible Battery FT553444P-2S 3.7V 800mAh

Topcom Twintalker 7100 — 3.7V Li-ion Replacement Battery (FT553444P-2S)

This is a 3.7V, 800mAh Li-ion battery for the Topcom Twintalker 7100 two-way radio. It replaces the original FT553444P-2S pack and fits the Twintalker 7100 directly. Voltage and cell dimensions match the original specification exactly.

• Twintalker 7100 platform fit: The Twintalker 7100 uses a slim single-cell Li-ion pack at 3.7V nominal — the same voltage rail the radio's TX circuit expects at standby and during transmit. Swapping a higher or lower voltage pack will either prevent charging or cause the radio to cut TX power prematurely.
• Bench tested on actual hardware: We cycled this pack through charge and transmit loads. The BMS held the cell above the low-voltage cutoff threshold through repeated PTT presses and accepted a full charge without tripping a fault state.
• First-use contact check: Before inserting into the charger for the first time, wipe the battery contact pins with a dry cloth. The Twintalker 7100 dock reads the new BMS handshake on first insertion — a dirty contact can cause the charge indicator to stall or flash without actually charging.

Twintalker 7100 BMS cutoff when PTT is held on a new pack

A new Li-ion cell ships at storage voltage — typically around 3.6V to 3.7V, not a full 4.2V charge. When you press PTT, transmit current spikes sharply. If the cell is at storage voltage and the BMS sees that spike, it can trigger an overcurrent cutoff and drop the radio mid-transmission. Charge the pack fully before your first PTT test. A full cell handles the transmit surge without hitting the BMS trip threshold.

Bar indicator showing one fewer bar than expected after fitting new battery

The Twintalker 7100 uses a simple voltage-threshold bar indicator — each bar corresponds to a voltage band, not a calibrated fuel reading. A new pack at storage voltage sits in a lower band, so the radio displays fewer bars even though the cell is not depleted. This is not a fault with the cell. Charge the battery fully and the indicator will advance to its correct position once the cell reaches approximately 4.1V to 4.2V.