ULPT request: Car battery seemingly always dies weeks after warranty expires. How can I get a new battery before warranty expires?

To give more details, in case op is reading this. You've got some electronics somewhere drawing a tiny bit of power when the car is off. Think like the thing that saves the radio present when the car is off, just this is something that shouldn't be using energy. Honestly it's one of the harder things to fix without the right scan tool or meter. Unless you have some hunch, like the aftermarket cd player or something is Jerry rigged, it's going to be a pain to find. The way to find this as a home mechanic is put a lead on each end of a wire and check for continuity but theres so many wires in the car and most arent easily accessible. Many people junk old cars over issues like this when they arent mechanically inclined.