Hi, it's possible to charge battery for p4 with inverter for car? Are there problem?

There is a DJI car charger which works nicely as long as the engine is running.

I also use an inverter and the mains charger with a caravan battery and it works perfectly.   
Obviously you need one that produces at least 100W, 300W would be more sensible.
Not sure if you need a "Pure sine wave" inverter, some chargers blow up if you use a cheap inverter.

As long as your inverter (and your car obviously) can give 100W, there is no problem. Not necessary for a sinewave inverter but make sure your inverter is a reliable one.

Note that most automobile accessory plugs are fed by very small wires. For most things this is not an issue. However, small wires under load cause the voltage to drop. If it drops too low the inverter will switch off. I ended up having an inverter professionally installed with 4-guage wires running directly to the battery. I can charge 2 P4 batteries at the same time. I have also charged 2 Inspire 2 batteries at the same time. Theoretically I can do both pairs at the same time since it is an 800-watt inverter.

You need to connect inverter directly to battery posts.

I Have some information about inverter and UPS
http://powertronups.co.in/product.html