I noticed this the other day. I would start the car and when it would idle and a fast clicking sound was coming from the dash and all the warning lights were flickering "but only at adle speed". A couple days after my battery died completely. Me assuming, I thought the alternator was bad. I replaced it with a spare one I had "dont know if its good or not, looks new" and tried it again, no luck... I measured the voltage at the battery with the car running and not running this is what it came to.

Running- 11.34
Not-Running- 11.92

Any ideas on what this could be you guys? Its been sitting for a week now in the driveway and Id like to go out and run it again asap.

 

I'd say both of your alternators are bad. You should be getting around 14V at idle. Battery voltage alone should be ~12.5V. You can alternators tested at parts stores, so once you confirm it, opt for a brand new one. OEM Mazda alternators or other high quality remans (NAPA) will be your best bet. Some of the cheaper remans can be junk right out of the box. I have had 2 "new" reman alternators from Kragen that turned out to be bad, so watch out.