Battery gauge running low, but battery and alternator are good?

[josiahsm02]

Hey folks,

About a week ago I noticed that my battery gauge was a little low. I went to an autozone and they tested the battery and said it was bad. I went and bought a new battery and the gauge didn't change. I had autozone test the alternator today and apparently it is fine. Any thoughts or suggestions? I'm pretty sure my battery terminals are fine.

Could it be my belt or belt tensioner are bad? How can I tell if the tensioner is bad?

Here is a picture of where the indicator sits on the gauge

Thanks!

 

[Curious Hound]

Unfortunately, that is not a calibrated gauge with marked graduations to say “your voltage is X volts”. It’s reading within the “normal” band, so it SHOULD be ok.

The question is, what is the actual voltage. I recommend getting a multimeter and measuring to get actual values. With engine running, right after startup, voltage should be slightly over 14 volts, maybe as high as 14.5volts. This is to recharge after starting the engine. After 5 or 10 minutes, it should drop down to about 13.8 volts or below, maybe around 13.5. This is to maintain and to operate the vehicle. If it stays high, it will “cook” and ruin the battery, usually due to a bad regulator. If it goes below battery voltage, it won’t charge. That indicates need for an alternator. A fresh, new battery should be about 12.6 volts at rest. If less than 12, start shopping for a battery.

Clean, tight, non-corroded connections and cables on both positive and negative parts of the wiring are necessary for a healthy system.

 

[josiahsm02]

Thank you!