Something is draining new battery overnight, how do i locate the source

Look on youtube for Parasitic battery drain and watch until you know all the in's & out's of doing the test you can do on your own to locate it as some test should not be performed on all models or in some instances just done a different way so the computer is not in harms way, and not all video's explain this but may lead you in a wrong direction as the car they are working on will not affect anything and some just give better tips, I know how to do this and done so before video's but still watch everyone I could find on the subject some people are just better to understand or just plain funny.

I have a 2004 Mini Cooper battery drains out I. A day check the alternator already but it’s good new battery to

Parasitic battery drain from a bad electrical part of short in a wire.

I have a minicooper and bbn is draining my battery what couse that