based on the title... the battery. HOWEVER, the battery tested good. CA, CCA, and voltage all good. now for the back story. I was driving yesterday, a/c not turned on, was running 13.5v. turn the a/c on drops to 12.5, 12, 11.5. the ac turns off then back on. but voltage remained around 11.5. Lights were off, as was the stereo. I go to start it this morning, and got the chimes and all, but wont crank over. tried to jump start, nothing. Took the battery out and had it tested 3x...was good. I have a new alt(could be a janky POS). I have checked the grounding, fuses, and looked at a few of the posts about clutch safety switch(something about a magnet to fool it, i moved a magnet around the thing and no dice), as well as the master cylinder. checked the round black connector next to the radiator, had 12v on the green wire.

Suggestions, ideas?

 

Ok...so anyone have a I.D 10t form? I thought i had all the grounds checked. The one on the pass side from chasis to motor mount was slightly loose.... tightened it down ALL the way...started right up. K.I.S.S.

 

USMCXD,

I see that all is good now with your car. BUT does the voltage still change when turning the A/C on? is it a normal behavior? I was monitoring my voltage since i just put a new alternator in and noticed the same thing when i turn on my A/C. Once the A/C is on even though the compressor is off voltage stays low. an drops just how you described. ( Car restarts no problem and i cleaned all ground straps and even the matting between the mount bracket and the engine itself.)

I have a whole right up on my issue i am posting shortly.

Thanks
Tom

 

it does still drop, but only to 14v/13.8v even with the lights and stereo with AC on. I did see a quick drop to 12.5ish when i initially turned on the ac, but it came back up. Ill get more when i get home and on an actual computer

 

So, as im still learning the quirks of the mini. But a few searches seems to point to 1)physical connections, (alt, battery, grounds in the engine bay and trunk[for the S] 2)Bad battery or alt, 3) belt slipping or something in/on a pully, or worn out belt 4) crankpully going bad. The last one gives other indicators as well.
I may be off base, and anyone please correct me if im wrong, but that is what i found so far.