Time to be alone and rest. To have no demands put on them by others.
I’m an extrovert, and I don’t use the term recharge my battery for myself, but when I was younger I needed a lot of sleep; and as I age, even though I don’t need as much sleep, I am still obsessed with getting enough. I firmly believe lack of sleep causes an increase in illness, accidents, and deaths. Sleeping is like charging batteries in an electronic device.
Even as an extrovert I want some quiet time away from people putting demands on me. I like being able to close the curtain and not constantly be on. I can do it with other people around, other people like me, but usually people will accuse people like me of being lazy, and that makes it better to do it alone. Sleeping late, taking a nap, watching TV, usually are looked down on by US society, but that’s how I stay healthy and recharge mentally and physically.