Battery Keeps Dying - Battery, Alternator, or Voltage Regulator???

[Worktofish]

I have a 2006 XLT Explorer 4x4 4.0L

I have been having trouble keeping the battery charged, and I am not sure if it is the battery or charging system. The battery is 2.5 years old.

At first, it was slightly harder to start (an extra crank), so I thought it might be bad fuel. The battery showed ~11.25 volts, and ~13.25 volts when the vehicle is running.

The battery terminals were dirty, so I cleaned them and charged the battery for a couple of hours with a 10 amp charger. I was just about to leave on a 6 hour round trip, when the car would not turn over (click-click-click). I jumped it, but I didn't take the trip.

I charged the battery overnight, then took it into the tire/battery store that I bought it from (Les Schwab – a NW based store with a good reputation). They measured 12.4 volts on the battery and 13.4 volts when running. Because it showed 12.4 volts, they wouldn’t replace it (which doesn’t surprise me).

I charge it at night, however, it keeps dropping down to ~11 volts after a day or driving.

If I am showing 13+ volts when running, it can’t be the alternator or voltage regulator, right?

 

[Lukas2009]

My last battery died after two years. It was a BOSCH S4.

 

[Flag Gibby]

It is not the voltage of the battery that they should have checked, but the capacity of it. A car battery can have a decent voltage reading but very little of the original capacity, especially if you check it on the vehicle just after you turned it off.

It does sound to me like your alternator and voltage regulator are just fine since the vehicle voltage is just over 13v running idle (suggesting that it is charging the battery at idle). The question is what happens to the voltage when you turn on the headlights; if it maintains the voltage then the problem is with the battery.

 

[Worktofish]

They checked the system while running and "under load". The readings were 13.4v and 13.0v, respectively. I should have checked what "under load" meant, but I assumed it was with the lights and A/C on. However, with the daytime running lights, the change between the 2 values seems consistent. They stated that the readings should have been ~14.5v, but was a little dubious.

Now that you mention it, they did say that the system had (to my memory) ~630 CCA vs. 850 CCA new (at 0 degrees).

Should I take it to another shop or wait until the battery drains some, then have them check?

 

[Flag Gibby]

Do this test and if the battery passes then it is something else, but usually once a battery is drained it never recovers very well.
http://www.popularmechanics.com/cars/how-to/repair-questions/4221215

 

[Flag Gibby]

Since my original Motorcraft battery has just about the same amount of capacity left in it I decided to pull my numbers for comparison for you just to see what these newer vehicles are supposed to be putting out instead of the numbers that I have stored in my brain from carbureted engines from days past.
This is what I got: voltage after overnight before starting is 12.55 V, voltage after starting with no load and idling is 14.5 V, voltage under load (lights on, stereo, AC with both blowers on max) 14.2V, voltage at alternator under load is 14.4V.
My numbers don't necessarily mean that the alternator is bad, just wanted to show you where my numbers are. I would say to check the output at the alternator and see what it is putting out. If it is at 13.5V or higher under load then the alternator is not running great but it is still putting out enough voltage to keep your battery charged up.
Depending on your testing results you could need a new alternator and battery.

 

[Worktofish]

I didn't charge my battery overnight and took it back to have it checked by another Les Schwab (the one I usually deal with). This time, I watched as they performed the test. The test came back with 220 CCA, and they replaced the battery.

So far, it runs much better. However, I still have similar numbers with the new battery. It may be my voltage tester - it is an older analog multimeter. I think I had better upgrade, given the prices for new digital multimeters are so cheap now.

I have not run the (Popular Mech) crank test yet, but I will wait and see if I have any problems going forward.

Thanks for all your help.

 

[Flag Gibby]

Yeah, I would say get a new craftsman digital meter something like model 82345 comes in very handy all the time and only $20. I have the older model 82344 and am always using it.