Battery light keeps coming on

[Birddog1955]

My 06 Explorer's battery light came on so I reset it so it would go off. A few days later it came on again and then a few miles down the road it went off. A couple of days later it came on again and stayed on, when we got home I used a multi meter to check the battery (with the engine running) and the reading was 14.20.
With the engine off and no acc on it was 12.79.
The next morning I check it and here are the results;
Idling-
Engine off : 12.79
Engine running: 14.19
Engine running with acc on: 13.99-14.07
Engine off acc on: 12.04
2000 RPM-
Engine running: 14.24
Engine running with acc on: 13.98.
Any idea whats going on.

Thanks,

 

[tripplec]

Test by doing the following watching what the meter drops to. Should not be lower than 14.0 ideally but certain not below 13.8VDC

- meter on idling the turn each one on adding the loads
- head lights
- high beams
- blower on Hi
- rear window defogger
- AC if you want

With all that running you're pretty much putting the max load on the alternator. If it drops below 13.8VDC rev the engine a bit (at least 1200rpm) and it should come up.

But odds are your alternator is failing or you battery has a cell dropping in/out from some plate issue.

 

[Tech By Trade]

By any chance do you hear a slight clunk before the light comes on?

 

[tripplec]

I never looked at the Explorer alternator but if that engine uses an ADP (special pulley) they are know to fail and take out the alternator. Some smaller engines have them to control load and vibration.

 

[Birddog1955]

Test by doing the following watching what the meter drops to. Should not be lower than 14.0 ideally but certain not below 13.8VDC

- meter on idling the turn each one on adding the loads
- head lights
- high beams
- blower on Hi
- rear window defogger
- AC if you want

With all that running you're pretty much putting the max load on the alternator. If it drops below 13.8VDC rev the engine a bit (at least 1200rpm) and it should come up.

But odds are your alternator is failing or you battery has a cell dropping in/out from some plate issue.

Thanks for the info.
I tried the test snd here is the results;
14.42 at start of test, I added lights, high beams, blower, rear defroster, air conditioner, defroster, seat heaters and rear air conditioner, at the end the reading was 14.09 any thoughts.

 

[tripplec]

Alternator is good, that much I'll say for sure. Its passing the load test. Unless there is something wrong with the bearing and malfunctions on the highway but you should hear that even at idle. Losening the Serp belt to feel the shaft is the only way to feel the bearing spinning or whabble.

I 'd check for loose connections or badly corroded rusted grounds, braided straps used. Having the battery load tested on a rig (if you have time to pull the battery) Loosen the secure clamp bolt FIRST !! It may be rusted and may not cooperate at the auto store. Cable corrosion from salt back of the connector is a possibility as well. Check around moving the cables somewhat and even a ground positive cable shorting to the chassis on its route to the starter or other contact is possible. It doesn not sound like its either the battery or alternator but batteries can go open internally on a whim or some other fault.

 

[MotorCityFats13]

your test sounds great..... I wish mine got over 13.5vdc with all acc on and 70mph...... if i ever see 14.4 its for 45 seconds after I start it up and battery is a brand new AGM and reads the same 24hr resting voltage of 12.0vdc as my replaced motorcraft battery with 2 cells at 50%..... there are other threads and alot of people have my same problem..... I didnt even know we had battery lights..... I added a digital volt gauge because I didnt like not having anything

 

[michael loibl]

Mine barely puts out 13.0 at idle with Nothing on. As soon as I bring it up to about 1,100 RPM, I get 14.5

If I turn on headlights and blower at idle it drops to about 12.2

Even with lights and air conditioning I can see 14.5 volts as long as revs over 1,200.

It's been doing this for over a year and still no battery or charge light has ever come on while running.

 

[MotorCityFats13]

it sucks because my amps only see 11.8 under heavy bass tracks...perfect formula for clipped signals and fried over worked equipment .... has to be a solution other than buying a $400 alt

 

[tripplec]

Mine barely puts out 13.0 at idle with Nothing on. As soon as I bring it up to about 1,100 RPM, I get 14.5

If I turn on headlights and blower at idle it drops to about 12.2

Even with lights and air conditioning I can see 14.5 volts as long as revs over 1,200.

It's been doing this for over a year and still no battery or charge light has ever come on while running.

Don't know what engines some of you have as nothing or no signature!!

However, low alternator voltage without any added load but fine at higher RPM would have me suspect the alternator is too slow at idle. Whats the idle speed? How much higher for the voltage to rise to 14.x 1200 is not an idle rpm but a slow cruising RPM. A weak battery would have its base power drawn to or below 12.0V with engine running is unusual. Bad connection may also be part of the problem

 

[cron9900]

I had the same problem for over a year. Twice I needed a jump after the battery light stayed illuminated. I checked everything and even added an additional ground circuit to the engine compartment. My alternator was bad. There a a few diodes in there that fail "sometimes." I waited too long and had to replace my battery as well.

 

[Birddog1955]

Thanks to everyone for the info.
I took it over to O'reillys and they checkedit snd the battery and altenator were good. They did say that they read theres a wire under the dash that might be the issue has anyone heard on this and if so which one is it.

Thanks again.