Charging issues

Rot Box

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With my mulit-meter on my battery I'm getting 12.3V while the engine is running. I had the alternator checked and they said it was good. I replaced the voltage regulator, and also measured the resistance of the wires (orange and white) between the regulator and the alternator and it looks good.

Any ideas? Could it be anything else? :dunno Thanks,

Andrew
 

Rot Box

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Crap I forgot to mention. I jumped the A and F terminals on the voltage regulator plug and the alternator definitely sounds like its kicking on however my volt meter shows no change it's still sitting at 12.3V.
 

SLC97SR5

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This is right after the new batteries were installed?
 

Rot Box

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That's correct. At some point in time someone removed the battery indicator bulb in my dash :rolleyes: so I assumed my old batteries were bad when they actually weren't being charged in the first place. Not too upset I guess the batteries were pretty old anyway.

Not sure when the charging stopped my dash gauge is borderline worthless.
 

riotwarrior

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Some alternators need to rev to make power...simple nuff...not all do 13.5 + at idle, as a matter of fact more don't than do in my previous experience....

Now a 3 G usually produces good current right outta the gate.

my observations only...others may have differing experiences.
 

Rot Box

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Thanks Riot ;Sweet

I've been letting it run for a bit and voltage has dropped to 12.1V.. I went out and throttled it up a bit and the volts quickly jumped to about 12.5V. Since I added a new bulb I noticed the battery indicator light is not coming on since I installed the new regulator. It stayed on with my old voltage regulator...

Thinking I might throw on a new alternator. It's $120 from Ford.. Who knows how old mine is. Might be cheap insurance in the long run?

I swear I'm going to be a professional Ford mechanic when I'm done fixing all the issues this truck has LOL
 

sassyrel

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Thanks Riot ;Sweet

I've been letting it run for a bit and voltage has dropped to 12.1V.. I went out and throttled it up a bit and the volts quickly jumped to about 12.5V. Since I added a new bulb I noticed the battery indicator light is not coming on since I installed the new regulator. It stayed on with my old voltage regulator...

Thinking I might throw on a new alternator. It's $120 from Ford.. Who knows how old mine is. Might be cheap insurance in the long run?

I swear I'm going to be a professional Ford mechanic when I'm done fixing all the issues this truck has LOL

this voltage your reading,,from where?? dash gauge???? get a GOOD multimeter,,then read it....you may be chasing a non existent problem...
 

Rot Box

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I'm just reading it off the battery terminals is there a better place to read from? Using a high quality Fluke 179 meter. Dash gauge works as good as a factory gauge can... Which isn't very good at all LOL

EDIT: I should say the factory gauge is reading where I think 12 volts would be. In other words the pointer is on the N in 8 [NORMAL] 18. Could be more could be less the world will never know lol.
 
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sjwelds

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Factory gauge?? What a joke LOL Mine moves around at will. At least it does move, unlike the oil pressure gauge lol. Haven't tested the charge recently but it does have a less-than-a-year-old alternator on it...Starts great and the battery light doesn't come on so I'm good AFAIK
 

franklin2

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Take your meter and with the truck off, measure the voltage at the bat output lug on the back of the alternator. If you do not get 12v there, then the fusible link is burnt out. This is usually caused by changing/messing around with the alternator wiring without disconnecting the battery. Happens all the time. Then the alternator is just out there by itself, not charging the battery because the fusible link is blown.

If you get 12v on the back of the alternator, some other things to check;

Put your meter lead on ground and put the other lead on the "I" terminal of the regulator(red/green wire) While holding the meter, get someone to turn the key to run but don't start the truck. When they do that, you should get voltage on the "I" terminal, this comes from the lightbulb in the dash and brings the system online and ready to charge. If you don't get anything, you still have dash problems.

The "A" terminal on the reg should have battery voltage at all times. This terminal is the monitor for the voltage regulator, the regulator uses this info to tell the alternator how much to put out.

The "S" terminal goes directly to the alternator.

The "F" terminal is the output of the regulator and more or less voltage on this wire will vary the output of the alternator. When you jumped the A and the F, you put full voltage on the F and the alternator should have gone wide open. It may have, but you didn't see it if the fusible link is burnt out.
 

Rot Box

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Where's your idle set?

I have it bumped up a little bit. it's around 700rpm warm idle.

Take your meter and with the truck off, measure the voltage at the bat output lug on the back of the alternator. If you do not get 12v there, then the fusible link is burnt out.

The "F" terminal is the output of the regulator and more or less voltage on this wire will vary the output of the alternator. When you jumped the A and the F, you put full voltage on the F and the alternator should have gone wide open. It may have, but you didn't see it if the fusible link is burnt out.

Thanks a bunch franklin that helps a lot ;Sweet I just went out and checked and there's 12.4 volts on the back of the alternator which is the same as what the batteries read so hopefully it's good to go. My alternator definitely made a sound like it was ramping up but nothing seemed to come from it.

I ordered up a new alternator today. If it works great if not I'll keep digging I guess.
 

nic55kel

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It takes at least 14.5 volts to charge maintenance free batteries fully!
Once they are fully charged the maintain voltage is around 13.5.
If you are only seeing 12.4 volts at the alternator output something is wrong and the batteries will die.
One problem with older vehicles and newer batteries (maintenance free) is that system voltage requirements are higher for the no maintenance batteries.
 

Rot Box

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Thanks again everyone ;Really

I received my new alternator today from the Ford dealer. It's a reman unit (new isn't available) and it's rated for 70A. My truck has the camper special package which included the 100A alternator... Turns out they don't offer that one anymore so I went with the 70A. My old alternators terminals were also clocked at 12:00 whereas the replacement alternator was clocked at 9:00.. It wasn't an issue though. Everything hooked up just fine. Hopefully 70A will be fine for my truck and my smallish camper.

The new alternator fixed the charging problem. It's been charging at a steady 14.2 volts since I installed it. It has a 2 year warrantee I'll post back if I have any issues with it ;Sweet
 

IDIoit

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My truck has the camper special package ;Sweet

this is the 91 you speak of, right? please tell me it has the tool box in the bed!

i dont know when they deletd this, but i love the bed tool box in my 71!
 

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