Welcome to the Forums, and congratulations on a great first post.That is correct. The big metal part inside the "port" is the positive side from the battery.Now, have a look at the SAE cabl… (View Post)
The thin wire (or maybe coiled wire) that extends from the tongue to somewhere on your vehicle. It controls an emergency brake that activates if the trailer breaks away from your vehicle. Look for it… (View Post)
The real test, though, will be how your battery reacts when it is not plugged in to any charging system. It needs to be measured when "at rest". (View Post)