Also, start with a fully charged battery. And if using it off of battery power don't drain it all the way. Maybe when it gets to 50% put it back on the inverter and start the engine.
The battery will act as a buffer (capacitor) for you. And when drained too low it will put a stronger draw on your inverter.
Most inverters have a modified sine wave. Those are the type that read 90 Volts AC from a normal digital Multimeter. And I used it on my IBM Thinkpad just fine. But, that doesn't mean it will work on every laptop
fine.