Good inverters - clearly thin cable

Property me the inverter acquired due to the very high performance - unfortunately, sent back.
He works quite quietly, provides no load fairly constant at 235V min.55Hz. Under load, this then begins to sway properly according to my instruments, from 210 to 240V everything was there and thus moves within the tolerance levels of most devices. The fluctuations in the rate, however, are enormous, from 20 Hz to 120 everything was there and nothing really constant. As load 1200W were connected.
Even with this relatively low load compared to the maximum power to the supplied cables heated enormous, continuous operation I have ruled for me. The cables have an almost 2mm thick insulation, the copper wires are not fixed to each other, have a lot of game. The total cross section is dimensioned clearly too short. After all, "flow" at full power over 160A on the 12V side. After a rule of thumb, therefore, should be at least 16mm ^ 2, thanks to power dissipation rather more. In particular, for the high potential of making power about 3000W (> 250A). The losses due to the heating cables reduce the efficiency enormously and increase you risk of fire, just 2 minutes from the cable minutes was thermal imager above 70 ° C and began to smell.

For my purposes, the too many points were not fit, so he went back.