2013 Buick LaCrosse battery being drained while off

How old is the battery? It might just be time for a new one.

I just had the battery starter and alternator all checked and they are all perfect. Even after having to get a jump just to get to mechanic to check those things the battery is good they said. They say there is something pulling power from battery even when the car is off. I have no clue.

I had this problem in my 2013 Dodge Journey, after purchasing 3 batteries (2 were faulty) the problem ended up being my spark plugs.

A sulfated battery can lose it's charge quickly, or it may not reach it's full charge, you have to do a proper load test and not a simpler check for voltage. That said, if you are certain battery is good, and you feel a parasitic drain is killing it, then you'll have to trouble shoot for that drain. Lots of guides online for that. If the drain is killing a fully charged batter in mere hours then it has to be a major component draining it, like an electric motor not turning off. (Cooling fans for instance.) Most minor parasitic drains take days to kill a charged battery.

Buicks are notorious for parasitic battery drain. In the Lacrosse, the culprit is usually the radio, which is tied to the #4 mini fuse in the passenger compartment under the dash on the driver side. If you remove this fuse and the battery drain ceases, you have found your problem. Fixing it is an entirely different matter.