I tested the voltage on both of my batteries today because I'm getting a low battery code on AE. The voltage for the passenger's side was about 14.3 and driver's side was 12.7. When I tested them with the engine off the drivers was about 12.8 and driver's side was 12.7.

It looks like ther driver's side battery is not charging. Is this possible and why would it happen?

Thanks,
Drake

 

Whens the last time you disconnected the battery terminals and cleaned them down to shiny metal?

 

I cleaned the posts just before testing the voltage.

 

I would have the batteries load tested,could be a bad battery.The problem will probly be a bad connection or bad battery

 

Mine was doing the same thing a while back. I thought the posts were clean but when I took a wire brush to it, the gray turned shiny. I realized how much oxidation was on the lead and was preventing a charge to reach the battery. Like was said above, make sure to clean to shiny metal.

 

Poor connection.

Steve

 

is one bat disconnected when you test if not they will both test good, mine did the same, unhooked one side and checked volts, the pass side was 11.2 driver side was 12.5 both connected they both were 12.4. when both bat were connected and truck running both bats read 14.2 v. i replace both batteries all is good now.

 

From my understanding the only bat directly connected to the alternators is the passinger side. The only way the driver's side is connected to the system is throught the cable going over the radiator. DO NOT discard the batteries just because the driver's side failed on the first try, make sure that bat is FULLY charged before you test it. And check the resistance in the cable for that side.

 

If you have the engine running and the cables clean, you will see the same voltage at both batteries.

Steve

 

A big thing to know with dual batteries is that the alt conects to the pass side and then the power goes to the driver's side through a cable hooked to the pass batt. This gives us more power storage.
If you disconect the driver's with the pass conected (ex: broken cable over radiator, bad connections, or bad ground cable) the pass batt will charge and the driver's won't.
If you disconnect the pass side and not the driver's (ex: corrosion at pass bat only, or broken ground cable at pass bat) then the driver's batt will charge and not the pass.
But if you disconnect power BEFORE the pass batt, then NEITHER battery will charge (ex bad alternator, bad cable from alt to pass batt).

A battery will test BAD if it is drained. If the cable going to the driver's battery is broken or there is corrosion, or if the ground cable is bad then that battery will not charge, it will start to drain over time and will test bad when it just needs a charging. SO NEVER CONDEM A BATTERY THAT HAS NOT BEEN CHARGED PROPERLY! This can be an expensive ($200) mistake. Let both batteries charge overnight using seperate cables then test them. IF ONE FAILS REPLACE BOTH! or if you don't have a charger, you can switch them (driver to pass and pass to driver), drive for a day and retest, if the problem goes away then you had a bad connection (that you cleand when you switched them RIGHT?!) IF it continues, then there is a problem with the electrical to the driver's battery, if it switches (pass batt reading weak) then you have a bad battery.