Yeah. About 4 hours. It is most likely one of those semi-conductor refrigerators. It doesn't have a compressor nor coils, so it is very quiet. It won't make anything freeze. If you allow it to breathe, it will work nicely to keep drinks cold. So don't pack it away in a tight little cubby-hole. I loaned one to my son, since this type of fridge doesn't get things as cold as a regular fridge, he thought it was broken and threw it away without giving it back to me. I was upset!
I have a friend who gave me what I would describe as a super mini fridge. Its about a foot tall and half a foot wide. It can probably fit like 2 water bottles in it. I plan on just keeping it in my room (if it even works.) My question is how long does it need to be on and running before I can use it or before it cools down. I'm thinking like a few hours?