Basically, you can always connect directly to the battery, I always do it that way. Your Noco is also protected against polarity reversal, so as long as you don't press the (!) button for 3 seconds, you can't do anything wrong!

However, if the battery is not connected properly, your electronics in the vehicle could be damaged if you do not connect it to the body. Conversely, you would have had completely different problems... 😉

The negative clamp on the car must be connected somewhere to the engine block / earth and "not" directly to the negative terminal of the battery.