Ctrl Alt DeFeaT

So a few days ago i tried to start my car in the morning and i got nothing. no lights, no sounds, completely dead, the dome light didnt even come on when i opened the door. later that night i tried again and it fired right up. Today i tried to start it again in the morning and it was completely dead, no lights, nothing, again. when i came home from work and tried again, the lights came on and when i turned the key the lights dimmed, temp gauge jumped to max, and i heard a single small quiet click.so i grabbed my volt meter and checked the battery and it read at 12 something so i tried to start it up again, it cranked a few times and turned over but sounded like it had to struggle towards the end of the crank to get the engine fired up. so from the time i tried to start it and heard the click, to the time i got it to actually start was like 15 minutes. also, my car usually has trouble starting after heavy rains idk if that would be related to whats causing these problems. it didnt rain at all here today. any point in the right possible direction would be appretiated, thanks!

Ctrl Alt DeFeaT

update: i got some battery terminal cleaner and some wire brushes and cleaned off a bunch of rust on the bolts. there was no rust in between the cable connecters and the battery itself, just on the part of the bolts that the socket goes on. dunno if that would make a difference or not. it started up fine afterwards but idk if thats because i cleaned the bolts or because i had just started it 30 minutes earlier. it just seems weird how it goes from completely dead with no lights, to having power with all the lights but no crank or start, to starting up fine lol. is my car secretly repairing itself? do i have one of THOSE cars?

navy02ws6

Sounds like a connection issue. Battery cables/bolts were probably just rusty/corroded and not making proper contact with the battery. If everything on there is clean and tight and it starts, you're probably good to go. If you have problems again, I would start checking your grounds, and following the battery cables to see if there's a break or any other corrosion somewhere.