Check for a parasitic draw This [https://www.youtube.com/watch?v=KF1gijj03_0|video shows] how if your unfamiliar with the test . Once you’ve isolated the circuit test the continuity of the wiring of the circuit . You mentioned the low beams being the problem . If this is the actual culprit you may want to start with replacing the socket and checking ground for the socket. You may also want to check the ignition switch . If your bike sits outside and is exposed to the elements the key hole can actually be an entry point for corrosion of the ignition wiring if the spade that covers the key hole is doesn’t retract properly when the key is removed. You may want to replace the light bulb as this could also be an issue. But before doing any of this do the test as it may just be coincidence that the low beams are on when the battery dies. Hope this helps