I just recently bought a volt meter gauge for my 2006 rx8. Its one that plugs into the ciggerate lighter. It seems pretty acurate but my question is ... When i put the car into reverse its drops to 13.8. When i put her in drive she goes to 15.0 then down to 14.4.. While driving her with no load she will drop to 13.8.. Is this normal?!

 

Yes that is fine, it will fluctuate.

You just dont want it to be over charging (IE 15-17V) and you dont want it to be low (under 13V while hi beams are on & blower motor are on high)

 

Okay. She does jump to 15.0 when im going to reverse. Or sometimes drive. And at idle she stays at 13.6 when i drive her she goes to 14.3. Today at start up i noticed what appears to be a bearing sound. So im thinking maybe my alt is going bad.

 

Those numbers are perfect. I wouldnt worry about 15V for a couple seconds, its the constant running at high voltage which can damage your battery & electronics (mainly due to the amperage). Check your A/C belt tensioner, and actual tension of the belt.

If your worried about the alternator get a load test done, most places usually do them for free and that should tell you the exact condition of the alternator.

 

Alright, thanks so much..