Battery voltage 2013 Freightliner Cascadia

Sounds normal to me.

 

Check it at the batteries, not the dash gauge.

 

It's ok. 13.8 14.0 is best.

 

Fully charged 12 volt battery will show 12.6 volts roughly. In order for a battery to maintain its voltage it needs to be fed with a higher voltage than 12.6 volts. 13.5 to 14 volts at the battery and output stud of the alternator is pretty typical. If you get up to the 15 volt range you'll start cooking batteries.

 

running

 

At 13.5 it might be showing weakness. Usual is about 14.

Measure the batteries with all accessories running. If you can run headlights, heater, wipers and whatever else. And maintain 13.5. You'll probably be ok. If it's lower. The alternator is getting weak.

13.1 - 13.4 though is a sign right there. If you can find anyone that knows how to load test an alternator. They'll probably find it's going. But there's a possibility the batteries might be causing the alternator to show bad.

 

That is the way to tell if your alternator is charging correctly, by checking it with all of your accessories running.