Assessing truck battery health

12.9 volts. If not, your batteries are suspect.

 

It depends so many variables. From how clean your batteries are, to how many ecu's you have in the truck. A battery disconnect switch is a good investment if your truck is going to sit. Below 12.4 is a discharged battery, 10.5 or lower and it's junk.

 

That's not terrible. I imagine it still started. You can do a parasitic draw test to find out how much your batteries are being drained by things like the ecm and radio, which requires a small amount of power to keep the memory alive. Also keeping the batteries clean will prevent battery case drain. The best way to assess the battery's health, is to fully charge them, and load test them individually.

 

Ross is correct, it depends on several things and batteries should be isolated and load tested individually to evaluate their condition. Generaly ideal battery voltage with the engine running is between 13.7 and 14.7V. With the engine off, you should get a reading of at least 12.6 volts. If the battery isn't fully charged, it will diminish to 12.4V at 75%, 12V when it's only operating at 25%, and down to 11.9V when it's completely discharged.