Recently my 07 WRX started to have this weird issue that I've never seen before. I'll get in it, turn the key to on (not cranking) and everything lights up and comes on fine. I go to crank it, and everything dims down extremely low, and there is a bunch of rapid clicking noises, and everything stays super dim and sort of flickering. If I turn off the key, and turn it back to the on position (sometimes it takes a few times), everything will light back up and it will start just like normal. Today the problem actually caused the car to shut off about 1-2 seconds after starting, everything dimmed and motor died. No grinding or struggling coming from the starter as far as I can tell. Battery reports 12v (yellow top optima), and I've checked the connections going to the alternator and battery, as well as some of the grounds I can find in the engine bay, all which seem to be tight. I do have a stereo system installed, but both battery cables are well insulated and connections are all tight.
Anyone ever deal with a problem like this? I've tried to search and google stuff, but trying to summarize and find stuff about this problem has been pretty hard, and any help would be appreciated! Thinking about getting the battery load tested tomorrow, but if it still starts fine, would this be a battery issue if it doesn't always happen?
I tested the battery with a DVOM, and unhooked from the car my battery sits at 12.22V, and when cranking to start the car, it drops to 10.8V. I believe this is well within a healthy batteries range, but would a load test at a parts store tell a different story?
In my experience that sound is a loose or corroded connection somewhere. When I have had and seen weak batteries they almost always cause a different sound - cycling the starter solenoid which is a bigger lower frequency sound.
Yesterday I cleaned the battery terminals, ground by the battery, alternator too connector, ground by intake manifold, and the ground at the back firewall behind the TMIC. It hasn't reoccurred yet, and fired up this morning, could have been the problem but only time will tell.