Edit: nevermind... I'm dumb, lol. Cano figure out how to delete this thread..

So yesterday my truck was progressively cranking slower and weaker each time I started it until it finally resulted in a *click click click*... but it had been running totally fine otherwise.. so I got a jump and it ran fine and I made it 19 out of 20 miles home before it slowly died down to a halt on the highway and I just gave the battery 1 more quick little boost from a jumper pack which got me home.

So based on that, the alternator is what was keeping it running, right? Until the battery was so dead that it couldn't power the basic minimal stuff?

 

Nope, sound like the engine was running off of the battery and your alternator is not charging. Get a multi meter and test voltage at the battery. You should have around 12v with the engine off and 13.5v or more with the engine running.

 

Search "How Charging System Works"