Voltage went from 14Volts to 12Volts.

[trucku]

Since I have bought my truck used I have always had a constant voltage of 14 Volts, whether I was idling or driving.

Friday I noticed that my dash seemed a bit dim, but no charging warning light. I later noticed that my sunpro guage show 12Volts.

Long story short
I bought a rebuilt alternator.


Now my voltage is 13-13.8Volts at idle after few hours of driving. The voltage changes depending on my driving speed. I was worried about this so I went to PepBoys (bought re manufactured one from there) for a Alternator test. I thought maybe for some reason it was bad. So the tech hooked it up and it passed :Regulator Volts At idle. 13.96 Peak current 112.3 Amps and 13.7volts with AC on max, high beams on and fog lights on at idle.


The tech said as far as he knows the voltage should not have been constant 14volts. The regulator must have been bad and I risked overcharging.

I performed Fords load test with then engine at 2000rpm and everything on at full blast and the voltage will go up with the demand and engine speed to just about 13.9 volts. The lowest voltage I have seen is just is 13volts at idle. Nothing dimmed or flickered. The manual states voltage should be 13-14 volts, so looks like all is well and my regulator is doing its job and regulating, unlike in my old alternator.

Guess I have to get used to watching the volts go up and down with speed and load.

What sucks the most is I had to shell out $150 bucks when I have a perfectly good extended warranty. The dealer and warranty company are not open on weekends.

I have read plenty of times here that people are getting 14volts at idle.
I will see how this replacement performs.

ANYONE HAVE THE SAME RESULTS AS I AM AND NOT A CONSTANT 14VOLTS???

 

[BrooklynBay]

Keep in mind when you have an internal regulator, the voltage will drop when it starts to warm up. This is normal. These regulators are only passive, not active, so they will fluctuate. They only provide source regulation (to keep the voltage below a predetermined threshold), and will not regulate when the voltage sinks (drops under a load). Clean your battey terminals, and use an antioxidant.

 

[trucku]

Well it went from on day to another from 14 volts constant to 12. I am just curious why before it never left 14volts at idle or under accessory load.Then with the replacement it seems to "regulate" My battery terminals were cleaned a little while a go and has the the anti corrosion rings and dielectric grease on top after the terminals were connected.

I also checked for voltage drop as my Ford Cd recommended and everything is perfect. I pretty much went through the whole regiment of test recommended by the manual and cd. Everything now looks great. Again I am just curious about the difference in from constant 14 volts to a now
"regulated" 13-13.9volts

 

[BrooklynBay]

AlDive once had this problem. He had low voltage at idle, but nornal voltage as soon as he stepped on the accelerator pedal. He installed a different pulley on the alternator which was smaller than the original one. This would cause the alternator to turn faster at idle. Maybe the pulley on the first one was a little smaller?

 

[trucku]

I compared them both when I purchased the replacement and they are a identical. I have been reading my manual and going through the cd and nothing points to a constant 14volts at idle or under load and speed.


Thanks for responding BrooklynBay.

 

[BrooklynBay]

Check this thread for more information: http://www.explorerforum.com/forums/showthread.php?t=154990

 

[trucku]

I read it. I don't think its the same issue. The load and non load test requires you to bring your truck up to 2k rpm. I am not going past 13.9 (scanguage). My idle readings were all above 13.5 volts or so. Guess when I go to Ford for my cruise control fix they can hook her up and see what's wrong.

Ok thats it going outside to mess with it. Lets see if a few hours of sitting will reveal something else. I have about 12.8 volts on battery with truck off when I checked earlier

 

[BrooklynBay]

Scan it in the morning. It should be a little higher after sitting all night. The battery voltage is good, so it doesn't look like there is anything wrong with the battery. Check the battery voltage before you start it to see how it is with the normal drain of the clock, PCM, alarm (if equipped), etc.

 

[trucku]

Scan it in the morning. It should be a little higher after sitting all night. The battery voltage is good, so it doesn't look like there is anything wrong with the battery. Check the battery voltage before you start it to see how it is with the normal drain of the clock, PCM, alarm (if equipped), etc.

Ah.. ok sounds good

 

[trucku]

Ok waited till morning.
Scanguage showed 12.3 volts with key to run position (engine not on).
After start it showed 14.3 volts and stayed that way for a bit. On the highway at 60mph it settled to 14.1. During my 30 minute drive it would move up and down between 14.1 -14.3 at speed and stop lights. During this time I drove with my marker lights, ac and fog lights on. After a 4 hour parked period the guage showed 13.9volts after few minutes of running and went down to 13.7volts by the time I got home. Again I was driving with the AC, marker lights and fog lights on.I guess all is well and my alternator is actively regulating my voltage. Still wonder why my old one showed ONLY 14 volts all the time.

 

[BrooklynBay]

Thanks for the update. Was your other alternator the original factory one?

 

[trucku]

Your Welcome

Yes I believe it was. Only other indication besides the look of it was that the positive terminal boot on the alternator had to pried off with a screw drive and the bolt was covered with a dark yellow grease. It was dried and thick with a waxy sheen. The replacement came with its own bolt for the + terminal.

Update:
When i used to turn off my truck the scanguage would remain on for a few seconds afterwards and the 14volt reading would remain until it timed out. Now immediately after the truck is turned off you can watch the scanguage voltage drop from running readings until it times out.

Another note: I just remembered, I was hearing a weird sort of "whiny, howly" sound from my alternator side of the engine with stock unit. Now All sounds normal. I don't know if it was something else.