By the way. Consider some maths. The RCT 850VA only delivers 480watt. Thus the constant output it can deliver is o ly 2.1Amp. Therefore you can not drive much in terms of devices irrespective of battery size. For one. A huge TV 54inch will probably draw at least near 3-6 Amps.
I read everything. Here is my 5c. I did a lot of testing on the exact model. Hooked up meters everywhere to check amp, volts and resistance. Electronically possible. Practical... Nope.
Problem 1 is something not mentioned here. The tolerance of inversion. Remember, you are inverting only 12v to...