The double trace you get from the car mounted inverter has me intrigued.
To me, the output of the generator (an inverter) and the car mounted inverter should be the same. i.e. both produce 50Hz sinusoidal AC.
The only difference is one is getting DC from a battery, and the other is getting DC from a petrol motor.
I suspect that the car inverter is of poorer quality and there is switching between the upper and lower trace which a better scope would show..
Happy to be proved wrong or hear from those with more knowledge on this
The sudden ceasing of inverter output is be expected when the DC level drops... they just switch off.
Much different to the old generators (Which are actually Alternators as they produce AC - Alternating Current) which rely on motor speed to produce the correct frequency and voltage. When switched off or run out of fuel... the voltage drops and the frequency slows as the revs drop.
The inverter is a middle of the road one. But you could be right. But its never been an issue, and it mostly what I use when heading out. Mainly just charges the batteries I cant find a CD charger for.
I dont see the point? Cheaper to buy a quality charger. They are designed to take even the dirtiest power. As for inverters, most my stuff like appliance ac/dc adaptors and induction motor fans run fine on dirty power. Even lpg generators (non modern inverter) produce a decent sine wave.