So I haven't tried this with a PS5 controller, but PS4 controllers do work without a battery in them when plugged into a USB port. Well, at least on PC. We use a PC to test controllers at works and I often have the controllers in various states of teardown and plug them in to test them. You don't want to replace an analog stick and put the whole thing back together to find out that something isn't soldered back in quite right.so if you keep it plugged in at all times, it doesn't charge the battery and the power goes directly to the controller unit? I mean, yes on Xbox controllers this happens. If I toss the removable battery the controller still operates. This makes sense because they know players may not have a battery on hand and still need to be able to play.
But that may not be the case for PS5 controller. Since you can't remove the battery, I'm unsure of how it's circuited.