So here's what happened. I returned from a spirited drive the night before, pulled into the garage and shut the ignition (the ignition is on a seperate switch than the rest of the car) in gear so the engine doesnt diesel the way it likes to. I then rowed the shifter back to park. As it passed "R", there was a split second when the reverse lights came on, the brake lights were still lit, the headlights were still on, the alpine and amp were still blasting away and the heater fan was still running. The lights flashed out for a second the way I've never seen them do before. Confused, I shut everything and gave it a burst of starter just to make sure everything still worked....everything seemed ok.
I come out the next night to leave for my friends birthday and hit the key to start and the car is turning over veeeeeery slowly: rrrrrrrrrrrr-ru-ru-ruuu-rrrrr then not at all. I swore and then ran inside and got my spare battery and gave myself a jump. Now the voltmeter read its proper 13-15 volts and I hit it again. RRRRRRrrrrrrrrr-ru-ru-ru-ru-ruuuuurrrrrrr-nothing. More spirited sounding but still not really cranking. I pulled the corolla in and jumpered 3 batteries in parallel with a running motor and I nearly stalled the idling corolla behind me with almost identical results on my end.
aaaaaaaaaaaarrrrrgh! So I beg the parents for use of their wheels and go have fun regardless. I had the trickle charger charging both batteries for 2 days at that point so they were both nice and juiced up. I flick the key on and the alt light is very dim. I turn on ANYTHING(Like a turn signal) and the power goes cold out and I have to go out back and detach the battery cable for a few seconds. Bad ground? I ran a wire from the "-" to the master ground wire up front with both batteries hooked in parallel. Lights/guages lit better now and voltmeter showing 12-13 volts but if I power up my radio, the power still goes cold out (both batteries!). I detached starter lead at relay and use jumper cable from +. Nothing. Battery still showing good voltage at the terminals.
I then used the spare battery alone and my jumper cables. - clamped to headers, + touched to starter lead. Suddenly, it cranks at full blast. odd
I pulled my old battery and completely replaced it with the spare (like put it on the battery post clamps) and now everything works once the old battery is off the circuit. I had to reinforce the master ground and replace a single fuse but now I beg the question....
Why did this not work with jumper cables?!? (the starter experiment above tells me my cables were good) If I jumper my spare, it should effecively be the same as switching the posts. Why did that not work? Why should the fact that my old battery cant provide any current effect my ability to use the current in the spare to start the car?
Did my primary battery "short out"?
Why do batteries short out?
I come out the next night to leave for my friends birthday and hit the key to start and the car is turning over veeeeeery slowly: rrrrrrrrrrrr-ru-ru-ruuu-rrrrr then not at all. I swore and then ran inside and got my spare battery and gave myself a jump. Now the voltmeter read its proper 13-15 volts and I hit it again. RRRRRRrrrrrrrrr-ru-ru-ru-ru-ruuuuurrrrrrr-nothing. More spirited sounding but still not really cranking. I pulled the corolla in and jumpered 3 batteries in parallel with a running motor and I nearly stalled the idling corolla behind me with almost identical results on my end.
I then used the spare battery alone and my jumper cables. - clamped to headers, + touched to starter lead. Suddenly, it cranks at full blast. odd
I pulled my old battery and completely replaced it with the spare (like put it on the battery post clamps) and now everything works once the old battery is off the circuit. I had to reinforce the master ground and replace a single fuse but now I beg the question....
Why did this not work with jumper cables?!? (the starter experiment above tells me my cables were good) If I jumper my spare, it should effecively be the same as switching the posts. Why did that not work? Why should the fact that my old battery cant provide any current effect my ability to use the current in the spare to start the car?
Did my primary battery "short out"?

Why do batteries short out?