Didn't get far today as I'd like but here is what I have to report.
Multi-meter on the battery terminals when not running returns ~12.5V. This matches the battery test that supercheap auto did when they sold me the battery, I went and found the paperwork and double checked.
Car running idling in the driveway gives 14.25V at the battery terminals. The Cars dash was reporting 13.0V.
I checked every fuse and relay and found that the Engine Cont Relay was looking in bad shape.
Picture attached:
I replaced it and then took the car out so I could do post run tests.
(Which were planned prior to finding the relay in bad shape)
During the run the voltage on the dash stayed around 13V even at higher speeds (80-100km/h) where it was rapidly declining previously. I still had my sound system dropping in and out though. During heavy acceleration the voltage dropped down to ~12.5V and gradually returned back to 13V. Which again is new, usually once it drops it just continues downwards to 11V or so and then everything goes nuts. It also dropped a bit when ghosting down hills and then returned. Still the audio was playing up but the Tacko was fine the entire ride which was previously the first thing to mess up.
At home in idling in the driveway after the run Battery terminals have 14.0V which slowly dropped to 12.5V once the car was turned off.
The Engine Cont Relay was extremely hot to the touch after the drive. Inside the car the Blower Relay was also pretty hot but not as bad. I turned off the fan and the dash began to read 14V, tested the terminals and it also had 14V so they were agreeing for the first time so far.
I'm going to take it for another short run now without the blower running and see what happens.
I know there was a lot more advice given and questions asked and I do plan to get to them, this is just my very first steps. My multi-meter was dead this afternoon and the one place locally that stocks them (Our tiny bunnings) was out of stock so I had to wait around for a loan of one and thus didn't get much done today. Sorry!
