Its a low battery voltage issue, the first thing to check is that the battery terminals are snug and tight. Other causes and things to check are.
The voltage across the battery terminals…
ignition off standby voltage expect greater than 12.4v, if less fully charge the battery.
ignition on expect a slow voltage drop to no less than 12v
cranking the engine expect a voltage drop to no less than 10.5v.
engine running at 4,000 RPM expect between 13.5v and 14.2v. If less than 13.5v suspect the stator, if more than 14.2v suspect the regulator/rectifier but don’t panic buy parts as further tests are required to rule out causes such as poor charging system wiring, chassis grounds, connectors etc.
If it was mine I’d fully test and check the charging system for any faults which is simpler job than folk think. The parts to test in order are the battery, the wiring, the stator and the rectifier. Prove any parts have failed before any willy nilly repair or replacement. ElectroSport have an excellent guide and explain how to fully test the charging system better than I could here
enjoy the read