Tytera MD-390 Compatible Battery 7.4V 2050mAh

Tytera MD-390 / MD-UV390 / MD-680 — 7.4V Li-ion Replacement Battery

This 7.4V, 2050mAh Li-ion battery replaces the stock pack in the Tytera MD-390, MD-680, MD-UV390, and TH-UV8200 two-way radios. It runs the same voltage rail as the original and fits the same battery bay without modification. Capacity is rated at 2050mAh (15.17Wh).

• MD-390 / MD-UV390 / MD-680 / TH-UV8200 platform fit: These four models share the same 7.4V battery bay dimensions and connector pinout, so a single pack serves all of them. The BMS in this cell communicates charge state through the same contact configuration the radio expects.
• Bench tested on actual hardware: We cycled this pack through transmit loads on the MD-390 and confirmed the BMS held voltage under sustained PTT. The protection circuit tripped correctly at overcurrent — no false lockout during normal TX bursts.
• First insertion into the charger dock: If the dock LED shows a fault on first insertion, remove the pack, wipe the gold contact strip with a dry cloth, and reseat firmly. The MD-390 charger requires a clean contact cycle to accept the BMS handshake before it begins charging.

Why the MD-390 cuts out mid-transmission on a new battery

The MD-390 draws a sharp current spike the moment PTT is pressed — transmit current can jump well above the steady-state draw in milliseconds. A new cell shipped at storage voltage (typically around 3.7V per cell) has higher internal impedance than a fully charged cell. That impedance causes a voltage dip under the TX spike, and the BMS can interpret it as an overcurrent event and cut the output. A full charge cycle before heavy use brings cell voltage up and lowers impedance, which stops the BMS from tripping on transmit.

Bar indicator showing one fewer bar than expected on a fresh pack

The MD-390 uses a simple voltage-threshold system to display battery bars — no fuel gauge chip. A new pack arrives at storage voltage, usually around 3.75–3.80V per cell, which sits below the threshold for a full bar reading. The radio reads this as partial charge and shows one or two bars even though the cell is not degraded. Charge the pack fully in the dock until the LED goes green, then power on the radio — the bar indicator will reflect the correct state.