What size alternator do I have in a 2021 SXT 2 .7 EB? I have a 20 amp DC-DC charger installed to charge camper battery, and have heard that if it draws too much current it could burn up the alternator. I would like to thank that since this is the smallest charger Renogy sells, that it should not be a problem. Do I need to be concerned? Please put my mind at ease.

 

I added a Victron Orion DC-DC 30 amp to our 5th wheel feed by a 2020 F350 with dual alternators (397 amp). I'm sure 20 amps will not be a problem since many audio amps pull more than that.
Make sure you run heavy wire with a fuse or circuit breaker back to the trailer connection, you'll have voltage drop from the battery to the trailer. I used 2 gauge on the truck, 4 gauge to the DC-DC charger.

 

Your 2.7 STX should have a 200A alternator with a 2.67:1 pulley ratio. You can use the chart below to figure out what your alternator output is at various engine RPMs, just multiply your engine speed by 2.67 to get the alternator RPM. At a 500RPM idle, your alternator speed will be 1335RPM and your alternator output would be roughly 120A