If you want to check that the gate resistors are good just check the voltage at the gate to source with the scope. If the voltage is above 10 volts than the gate resistors are good at that value. 50 degrees on the fets is not so much you can add fan to cool things up. You may be pulling around 60 amps from the battery at 600w at 80% efficiency. Are you pulling a continuous load? or with amplifier?
Regarding current trafo it may be the case that you have too much turns on the secondary of the current trafo. Make less turns and put a load resistor according to the tripping voltage wanted in your smps. It is not the current passing but the load on it with the secondary turns and load resistor.
I will check the gate voltage of the fets as soon as I get home
about the current trafo
The core gets really hot (only when smps is under load) without any secondary winding on it ( just the primary winding of the ETD59 going through it)
I tested a few core that I have and the only core that didn't get warm was a green core but when I test this green core, the protection board kick in as soon as I release the high load from the output of the smps (when I connect a low resistance to smps output and hold it there, it dosen't triger the protection board but as soon as I release the load protection board react and cut the power)
I tried different secondary turns on current trafo but with same result
This only happened when I use the green core
thank you again for all your helps