Actually YOU are making it about control but telling yourself it’s concern. If it were truly concern, you’d have those concerns when he’s at uni too.
We have all, including myself, agreed that some basic courtesy is needed (although I have no issue with an “I’m off out now, see you later” as they’re about to leave - why do you need more than that? Why does he need to ask you permission to leave the house and how far in advance do you need it? My friend has just messaged me to ask if I fancy a wander to play some Pokemon go together. I’m going to put my shoes and coat on and then shout “see you later” to my husband and kids - according to you that’s a big no, no. But I’m an adult, and so is your son, so I can do that (my kids don’t need me to be at home for childcare)).
You clearly just wanted us all to agree you are right and your son is wrong as you won’t even concede considering a compromise, so you’re probably better off leaving this post now. But if you want to save your relationship with your son, listen to what the majority of us are telling you.
As for your older son - that was me at home. I had to be the good one. I had to do exactly what my parents wanted etc. I barely see them as an adult and I live a 3 min walk from them. My little sister was the rebellious one, like your younger son. I was so envious of her doing what she wanted when I couldn’t because of the expectations on me. Chances are your son feels stifled by you and is pushing back. And I don’t blame him. You need a compromise - you said earlier you wanted a middle ground. If you meant that, talk to him at a neutral time, and agree a compromise that will make you feel better, but that he doesn’t feel suffocated by.
Heres a suggestion - buy him a small power bank rather than insisting he checks his phone is charged. I have a mag safe one (you need a case that supports this) and it it tiny - no wires, just sticks to the back of my phone. If he were to agree to that, you would feel more relaxed about his phone running out of charge and he wouldn’t feel nagged.
If he’s going out, agree a time he lets you know by OR tell him that you will assume he’s out every day unless he tells you by x time that he will be home for dinner. If he’s doesn’t let you know, he will need to cook for himself.
Stop asking where he’s going and who with. Ask him to let you know if he’s coming home or staying overnight and check he has a key.
There are definitely compromises you can come up with, but you need to be prepared to admit it’s been about control not concern - because all of these compromises will help you to feel less concerned but won’t give you any control. Whereas what you are asking for gives you all of the control.