I am having trouble diagnosing this issue. My car battery will fall down to 11.5v or lower when left unattended after 2-5 days. I tried disconnecting the battery and the battery did not drain. I tried following various guides to try diagnosing the issue (pull out fuses one at a time and check amperage draw) but whenever I use my multimeter to connect between the battery positive and the disconnected negative wire bundle, I end up blowing the fuse in my multimeter because 10+ amps come through. This happens even when letting the car sit disconnected overnight.

I was planning on just living with the parasitic draw and dealing with it by using one of those screw-in battery disconnect things like this: However, it's a real pain because every time I re-connect the battery it lets out a big spark and a small honk. This happens every single time, regardless of how long it's been sitting there. Is this normal, or is this possibly connected to the parastic draw issue where something is deemed as being left on, so as soon as the battery connects it tries to surge 10+ amps every time?

Any ideas? And is the small honk normal every single time when connecting the battery?