Hi all, I have a 2011 Ranger XLT, 4.0, 5speed, with 32,000 miles! My battery light started coming on a week ago, starts out as a flicker and the longer I drive it, the headlights dim while coasting, step on the gas and they get bright. Battery light stays on. When I shut it off for 10 mins, its fine for about 10 miles, then it acts up again! Changed the alternator, and it still does it! Have put a meter on it as soon as it started and it was at 14.23! Could it be the battery? Thanks for any input!

 

Could be the voltage regulator starting to go.

 

I changed the alternator today! Is there another regulator?

 

Im not positive, but it either has a voltage regulator on the alternator, or it has an external one. If thats the case, it would usually on the firewall.

 

But usually when a battery itself goes bad, you'll have trouble starting because it wont hold enough reserve charge to crank. Everything will just go dim when you go to crank it. Once running, the alternator does all the work.

 

In the 2000's Ford added "Smart Charging", while there is a voltage regulator inside the alternator, it is now controlled by the computer(PCM).

Smart charge systems are designed to be used only with a silver calcium battery not the lead acid type batteries due to the voltages used which may damage a lead acid battery
and give incorrect readings.

"PCM monitors certain parameters such as the engine temperature, battery temperature and electrical demand.
If the alternator does not receive a signal from the PCM, the battery light is illuminated on the vehicle. This can sometimes be misdiagnosed as an alternator failure."

There is not much you can test on this type of system with out an Oscilloscope.
Is the battery the right type?

Key off, pull off the 3 pin connector on alternator, test pin3 for battery voltage, should be exactly the same as voltage at battery, if not check alternator fuse(s) in engine fuse box.
With 3 pin connector still removed and headlights or other electrics switched off, start engine, battery light will come on, test voltage at battery, should be around 13.8v, about 1.1v above at rest battery voltage.
That means alternator is "probably" OK.

And that's pretty much it without a scope.

And just as a heads up, you should not use a vehicle with "smart charging" to jump start another vehicle, or be jump started.
You can disconnect battery from vehicle, BOTH cables, then use the battery to jump start another vehicle, or charge the low/dead battery in your vehicle.

 

I tried that and the meter reads 12.46...With the truck off and running...It may drop to 12.3, but thats all!....The battery light did not come on when I started it!..Its the original battery! Going on 4yrs old!

 

With 3 pin connector removed the "smart" alternator will go in to default mode which will provide 1.1v above battery voltage, so alternator has a problem if battery voltage showed less with engine running.
Is it a Ford alternator, non-Ford alternators are often hit and miss with "Smart Charging"

Check voltage, engine off, on the B+ terminal on the alternator(the big wire terminal) it should have battery voltage, if not then main alternator fuse has blown.

 

Sometimes its good to change the battery and the alternator together. Especially sinse your battery is 4 years old.

 

The silver calcium battery with "smart charging" should go 7 years, but like all things there are exceptions.

Back in the "old days", 15 years ago, lol, yes a bad alternator could take a 4 year old battery to an early grave.

 

I know its been awhile, but here is an update on my battery light problem....It came on for the first time when I started the truck, put the e-brake on, light goes out, e-brake off, light on,...Kick the e-brake pedal 5 times, light hasnt come on since....I think the plug on the e-brake pedal was lose and that was causing the light to come on!..

 

New update...The battery light still comes on and off and flickers...

 

you could do a load test on the battery, see if the voltage drops a ton when you crank the engine....

 

I would do this, because it doesn't read like alternator is actually causing the problem.
Hook a volt meter up to watch it while driving, i.e. hook it to cigarette lighter plug in, you can get those plug-ins fairly cheap, watch if voltage is actually dropping when battery light comes on.

I doubt it is, since "kicking or moving the e-brake pedal" caused it to go off and on.

But there in lies a problem, the wiring under the dash is hard to track, my first stop would be Grounds, there should be a few in that area look for loose ground points