No my wireing isn't the problem.
I have learned from a leater experience that if you want to whire a +12V to audio amp or otherthings make if fat! very fat! so 21 (square mm) is a min I use. the 26 is to expensive and to powerfull for my use, I will never run JBL 1000W Subwoofer
I have now tested running Pc powered from wall (house power) and I get the same problem (I call it problem, or meby a little inoing point of using LCD), the LCD is a 10% darker in about 0.5 sek in the same time I turn on fog light or hig beam lights.
So I am goying to buy new car battery on monday. and I making it as big as possible. I hope for 80A but I am not sure there is such powerfull battry in a size that firs mounting place in engine room.
But I discoveret another thing.
It is that my DC-AC inverter make a lot of noise.
then I use it I get a small inoing sound in my speakers (the inverter and PC are grounded with 8 (square mm) cable. So I am decidet to go for DC-DC PSU @150 W.
But do you know if opus (the one I want to but) has a noise filter so I will not get this crappy inoing soung in my speakers?
BTW: it is not cables problem as I use triple shild RCA cables.
thnx for help