Alternator - Battery 19v reading

[Eric m Reza]

I have a 2003 Ford Expedition 5.4 V8 , I’ve been having a problem with my vehicle dying while idle at red lights and the other day at the drive thru it happens mostly when I have the ac and radio on together . Also have a starter issue and grinding noise when turning over sometimes bolth are accompanied together . I tested the battery with my meter and it reads 19V I measured the cable connections to my alternator and it is ready by at 19 as well . Any thoughts on maybe a voltage regulator issue ? Should I pay up and buy the alternator and new starter ?

 

[stamp11127]

No way in hell the battery can put out 19 volts unless the electrolyte has been "kicked up a couple of notches" raising the acid/water ratio.

If the engine is running and you read 19 volts charging, I would verify the meter is correct by testing another vehicle's battery with the engine off. All the interior & exterior lights would be extremely bright also with the higher voltage as long as they are not LEDs.

Grinding noise is the starter drive gear teeth not meshing with the ring gear on the flexplate. I would pull the starter and inspect the teeth on both gears.

 

[Gary Waugh]

Like Stamp, I have to question the accuracy of your voltmeter or the method you are using to measure the voltage, no way will a lead acid battery give 19 volts. If you have the engine running and it shows 19 volts you battery must be fried as it would boil dry at that voltage. You must have a bad connection somewhere causing a high resistance so the voltage is getting that high. I would start by getting your battery load tested and check all the main ground connections, Engine to chassis, battery to chassis, etc..

 

[Eric m Reza]

Sorry I am back and it was defenitely a faulty meter . I used a fluke and the battery read 12.6 . I put in a new alternator and the battery light came on immediately the car lights dimmed down and the radio shut off I tailed it to autozone to charge the battery , could the battery be destroyed from the previous alternator ? Is the new alternator trying to compensate for a bad battery and that’s why it won’t hold a charge ??

 

[Eric m Reza]

I recently read that it could be the OEM Alternator Wiring Harness ?

 

[Aspen03]

If the battery is reading 12.6v with key off, it should be at least halfway decent. Have you seen what it reads with a load on it? Being at autozone they'll usually test it for free. A bad alt can definitely kill a battery but it usually does that and they dont really tend to take much of a charge. Having a new alt installed I would say thays unusual to have everything dim or shut off unless there is another underlying issue. If the battery were just absolute trash, maybe but doesn't sound like that's the case if it works at all or it wouldnt start.

 

[Plati]

Now that you replaced the alternator … without conclusively diagnosing the original problem, you may have introduced one or more additional problems. May not have either. Can't tell over the internet. Maybe the original alternator was bad, maybe the new one is bad or for all I know you put in the wrong model alternator. Maybe you installed the replacement alternator incorrectly. Possibly a bad battery … or wiring … or the PCM … or ????

Sorry to be a negative Nancy but that's how I see this.
I think I would put it all back together the way it was originally, charge up the battery FULLY and begin a diagnostic process to determine what the issue(s) are.

12.6 Volts for a battery actually seems high to me, based on what my Expy batteries read. But then again you don't say how or when you measured that. Also I don't understand why you would take it in for a battery charge either, It was 12.6V?

 

[stamp11127]

Where did the alternator come from?

Battery basics:
The electrolyte is made up of H2SO4 - sulfuric acid and distilled water. It will have a specific gravity of 1.265 at 80F. Add .84 to that to get the cell voltage reading for 100% charge. That equals 2.105v. Six cells will total 12.65v at 100% state of charge.

So your 12.6v reading is fine. Load test the battery to see how sulphated it is which reduces capacity over time. Turns your big battery into a lawn and garden battery.

Could the old battery be destroyed? A load test will tell if it is good or bad. We can't tell you more since the readings were wrong.

Mrs ticker he is taking it in to be charged since he, like most people, haven't been taught how the starting & charging system works. They unfortunately are reliant on a few competent mechanics and thousands of parts tosses that call themselves mechanics.

 

[Plati]

So … I'm definitely not a battery expert, but I'm slowly learning. I agree / can see that 12.6V is a fully charged NEW in perfect condition battery. That's after a rest period of hours. If you charge it up with a charger it can go higher (temporarily). In the real world of Expeditions, my 2 batteries are almost a year old so I guess that can explain why they read less (about 12.4V). It doesn't mean they or the charging system is faulty, just no longer a new battery.

 

[stamp11127]

Nope, a fully charged battery will bring the specific gravity of the electroyle back to 1.265. Age doesn't matter.

During the discharge cycle sulfate is produced and deposited on the two different lead plates. During charging it is removed and mixed back into the water of the electroyte producing sulfuric acid. If the battery is allowed to discharge over a long time without a charge cycle(s) the sulfate hardens. This reduces the active plate area and shows up as reduced cold cranking amps/cranking amps. Internally the battery is getting smaller.

Discharging reduces the specific gravity of the electrolyte by reducing the amount of sulfuric acid and increasing the amount of H2O in each cell. Water has a specific gravity of 1.000

When a battery is charged the electrolyte is in a more active state and battery voltage will read above 12.6v.
This is referred to as a "surface charge" and can be removed by placing a small load on the battery for 10-15 seconds.