Set up inverter with 10mm* cables to a 48v battery bank. Plenty of ah in batteries. Good thick cables. Running no more than 48w output. Auto shutoff is set at 15w. Output power does not fluctuate. Inverter gives a "voltage overload" warning and cuts out every 1 or 2 minutes. This thing is currently unusable, brand new too. Any advice in settings? Currently set at 50hz 230v output.