Battery Light Coming On??

[bjtheman1]

I swear it's always something here lately....

My battery light is now coming on, but it comes on then goes off and so on.

My battery & alternator are both less than 3 months old, I charged my battery full last night. This morning checked my voltage on the battery with the car on & off and everything is fine.

What else could be causing this? It just started over the past couple days

[Ready 428R]

Rebuilt alternators are a crap shoot.You may have to exchange it for another one.PCM controls alt charging on these cars.If alt light works when key is on and engine is not running then pcm,cluster and related wiring should be ok.Was battery and cables damaged by corrosion?Ford batterys produce a lot of acid corrosion and damage the wiring badly.I have seen corrosion migrate down through the cables and cause high resistance.All kinds of problems occur when this happens.Some people have replaced alt multiple time before finding a good one.

[kansjfr]

I agree with the previous post. My 427R had an aftermarket rebuilt alternator on in and once when I was going through the gears near redline, every warning light (or so it seems) on the dash came on. I cleared the lights by disconnecting the battery. Then I noticed that even though it had the correct Motorcraft battery in it, the battery was bleeding out fluid from the top because the alternator was charging too much. Solved the problem by getting a PA Performance alternator from Stage 3 Motorsports. The alternator is expensive, but a bad alternator can really screw up alot of things on your car. Also, if you have a Stage 3 engine, like the 427R, the PA Performance alternator fits correctly and you don't have to cut any ears off the alternator case. It's kind of expensive (about $260, I think) but what isn't on these cars? Well worth the peace of mind in knowing you have the right alternator on it.

[Ct. Rich]

Get the battery load tested too. Some auto parts places will do it for free. Just because it's new, doesn't mean it's good!

[bjtheman1]

Still having issues. I've had the battery & alternator load tested and both were fine. My battery light still comes on and I noticed yesterday when I had my air on high that when at a stop it slows down then speeds up when I drive. ??? WTF??

[Pentalab]

Still having issues. I've had the battery & alternator load tested and both were fine. My battery light still comes on and I noticed yesterday when I had my air on high that when at a stop it slows down then speeds up when I drive. ??? WTF??

Your battery voltage is dropping at idle, then increasing when eng rpm increases. Mine sits at 14.2 to 14.4 at idle. Doesn't drop when I give it some gas. I watch the vdc on the aeroforce display...plugged into the ob port. But I can also see it with a DVM (digital volt meter plugged into 12 vdc jacks on my 2010). The alternator is supposed to be good for 80A at idle...and 135A once you hit 1500-1800 rpm.

This sounds to me like an alternator and/or regulator issue. It could be a bad /int connection somewhere too. Can you see the voltage while driving and at idle ? Does the 'voltmeter' on the dash dip a bit when stopped ?

[kansjfr]

Also, did you get a PA Performance alternator? If you bought an aftermarket rebuilt alternator, it's a crapshoot. Mine had a rebuilt Autozone or O'reilly alternator, don't know which, and I had all kinds of lights come on when the revs went up, when I got on it a little bit. The PA alternator is designed for the Roush, and is guaranteed for life. I know it's pricey, but do you want to keep changing out cheap aftermarket alternators? I agree with Pentalab that you have an alternator issue because the symptoms change with engine speed. Good luck.

[bjtheman1]

From alot of reading I'm hearing that these rebuilt alternators are horrible for our cars. Just ordered the PA Performance one, hopefully once installed it solves this crazy problems!

[bjtheman1]

I'm amused here. This past Sunday I cleaned my engine bay, sprayed it down and washed it out, etc. Well since then my battery light no longer comes on. LOL..plus I just got my PA Performance 130 Amp Alternator today! I'll be installed this alternator anyway this Friday just b/c it comes highly recommended for our cars.

[AutoXRacer]

Be careful with PA alternators, the only one I recommend is the FORD OEM!! I bought a PA Performance 130 AMP alternator and the very first time I ran it, it cut voltage at 3,000 rpm; my voltage would drop from 14.3 to 12.2.
They replaced the regulator and now it works...well at least it doesn't cut out throughout the RPM range. But I can't fully load my electrical system at idle; if I do my voltage drops to 12.3 and thats at the positive post on the actual alternator.
Another thing I noticed with my PA alternator is that its not steady like the OEM one. Upon pressing the brakes, turning on signal lights, etc, the voltage spikes from 14.3 to 14.5, 14.7, even sometimes 15.0!! Make lights, engine, and things really qwerky.

I know the Ford OEM is not pretty, but is sure works...14.3 volts solid!!! No matter what the load or rpm is.
I found out that the PA alternators are cheap chinese units powder coated all pretty. They sure are nice, man does it complete my engine bay...but performance wise, its highly questionable in my opinion.

Be very careful because if you drop voltage at WOT, your fuel pumps will be affected possibly causing a LEAN condition.

You should data log, RPM, battery voltage, voltage at fuel pump, just to see whats going on throughout the RPM range. Or just monitor your voltage.

Let us know what you find.

[mhenry1282]

Wouldn't it be pretty simple to yank the alternator housing apart and have it powdercoated? Can't imagine it would be that expensive, probably cheaper than the PA alt. I'll have to take a look at my V when I get home, I put one on my car shortly before I left and didn't notice any problems. Wasn't looking THATclose though...

[AutoXRacer]

I want to give PA another try/test... This time with a 200amp version and a pulley clutch installed.
Maybe I just got an off unit thats troublesome.

Although, I've been reading on other forums of guys with built engines having to ditch the PA unit for a stocker due to issues with voltage which ultimately affects tuning.


Edit: Never mind, PA Performance just gave up on me...they will be issuing a refund. I'm stuck with the ugly stocker...but it does perform perfectly.

[kansjfr]

I'm not discounting anybody's experiences, good or bad, with the PA Performance alternator, but when I replaced the alternator (which was a "new" rebuilt one from a parts store, don't know which one) with the PA one, my problems went away. No more carnival of dash lights, no more fluid leaking out of my battery. I'm satisfied. I imagine that all manufacturers have problem products and maybe that's what AutoXRacer got, maybe there's a problem with modified engines. Mine is completely stock.

[bjtheman1]

OK, now I give up!

I installed my new PA Alternator today, upon removing the old one I found that a piece of the back of it had broke off (the piece that has the bracket). So after I installed the new one OF COURSE my battery light comes back on! I just don't get it

[kansjfr]

Did you ever get your alternator light problem solved? If so, what was it? We'd all like to know.

[bjtheman1]

Did you ever get your alternator light problem solved? If so, what was it? We'd all like to know.

Nope, still having this issue. Cleaned the terminals well last week and made sure no connections were loose from the alternator. Battery light still on.

Soo......last remanufactured alternator I had=battery light would come on but go off when I increased rpms.

Now...new performance alternator=battery light comes on and stays on

[AutoXRacer]

Nope, still having this issue. Cleaned the terminals well last week and made sure no connections were loose from the alternator. Battery light still on.

Soo......last remanufactured alternator I had=battery light would come on but go off when I increased rpms.

Now...new performance alternator=battery light comes on and stays on

Have you verified the voltage coming out of the alternator? Use a multimeter, set it to 20V, black lead to chassis ground and red lead to the stud on the back of the alternator where the power cable goes to the battery.
See what the voltage is during idle.

Check the battery cable that runs from the alternator to the battery...make sure its not damaged.
Also check the PCM cable that plugs into the alternator and connects to the wire harness on top of the passenger valve cover near the PCV port.

[Ct. Rich]

Aren't you supposed to upgrade the cable with the PA ? Or is that just with the higher amp one?

[bjtheman1]

Alright, got home and found my new battery load tester came in...so I just checked everything out.

Here's all my readings.

With my Voltage Meter:
Car Off Battery Voltage - 13.8
Voltage from Alternator - 13.6

Car on w/heater & headlights on:
Battery Voltage - 15.5V
Alternator Voltage - 15.6V

With Battery Load Tester:
Battery Load-Good/Green

Charging System Test with Car on and acces. off-Good

Charging System Test with Car on and headlights & heater on- Good

mother of god!!! What is it?>>?lol

[Ready 428R]

Sounds like your tester reads on the high side by about 1 volt. Is the battery warning light on dim when engine is running or is it as bright as it is with key on and engine not running? Cluster could be bad or PCM causing warning light to stay on. Might need to visit Ford dealer or someone who can scan for body and chassis dtc's. Have you scanned for powertrain dtc's? Have seen a few pcm related issues cause charging system concerns.