Charging System Service Now - Argh

[ChipG]

It's back. Pops up every time I start or drive the car. Goes away sometimes and comes back. Last time this was the connector to the voltage regulator. Just to be sure, I replaced that again - no luck. Battery shows 12.2 volts with the car off, and voltage is over 14v car on, so alternator is holding voltage up. Both battery and alternator were replaced last year when the dealer couldn't figure out this problem. Could the voltage regulator on the alternator be bad this quickly? One other oddity happened once - I shut the car off, then got a push notification to my app that the car went into deep sleep mode. Checked the battery again and still at 12.2 volts, so it was really odd. Ideas?

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[Postal Bob]

Did the dealer check the BMS? Sounds like the alternator is not being allowed to properly chage the battery.

 

[ChipG]

Dealer work on the electrical system was last year. I fixed the issue in the spring, and it has now resurfaced. I can try a BMS reset anyway to ensure that's not it.

 

[Inthehighdesert]

This will sound cliche, but have you checked the grounds? Electrical problems can be extremely frustrating and a serious pain in the … to chase down at times.

 

[ChipG]

BMS reset didn't help. Ground connection at the battery was fine today but haven't checked others. I can take a look - I don't suspect corrosion or the like, but maybe something vibrated loose. The voltage gauge is stone steady while driving, by the way, so not looking like a voltage regulation issue at this point.

 

[JAJ]

When I had that message, my alternator was toast.

 

[Speedfreak]

I had the dreaded "Charging System Service" light on 6 months ago and the dealer replaced the alternator, which fixed the issue. From my research (which my dealer confirmed), typically, it is either the battery, alternator, or the alternator pigtail.

Best of luck!

 

[ChipG]

Yeah, this are my 3 prime candidates, too, with the challenge being that it "shouldn't" be any of them. All 3 were replaced last year. That said, in trying to diagnose, here's what I have:

Pigtail - source of the problem last year. Just replaced again, didn't help.

Alternator - if pigtail is ok, behavior could be explained by alternator (voltage regulator?) going bad. However, holds 14+ volts at the battery running at idle, voltage gauge reads 14.3V - 14.6V while driving, needle is steady and doesn't have big swings like it did last time, so doesn't appear to show the same symptoms.

Battery - now reads 12.1V after sitting overnight, which seems a little low. Car went into deep sleep mode immediately once yesterday which should only happen if battery is below 9.5V. While it's also pretty new, this summer the dealership twice let it sit for weeks until the battery was dead and jumped it. Wondering if that hurt the battery.

Other - maybe bad ground, connector, or wire somewhere (could be super difficult to find).

So, my thought is first to get the battery tested as that's pretty easy, and to do a thorough visual/manual inspection of accessible grounds and connections to see if there's anything obviously loose or broken. Any other ideas?

 

[ChipG]

Well, battery tested good. 12.1V still seems low after sitting just a night, so I'm going to drive it awhile and make sure to get it fully charged up to see if it never really got charged after the dealer let it go flat.

 

[Garfy]

Nominal battery voltage is 12.6V if the battery is fully charged (after surface charge is removed). If your battery is 12.1V, something is draining it or the battery could be defective. It wouldn't be the first time a battery goes bad after a year or less. I'd suggest you remove the battery (or disconnect the ground cable) and put a smart charger on it so it will bring the battery to full charge and then switch to trickle charge afterwards. Once it's charged, remove the charger and let the battery sit overnight or 24 hours. Test the voltage again; it should be 12.6V since nothing is draining it; if it's below (like 12.1V like you had before) it's probably a faulty battery. When we sold batteries at our shop, we had the new ones sitting on a rack for weeks and when we put a voltmeter on it, they're all at 12.6V which is what they should be as a lead acid battery generates 2.1V per cell.

 

[ChipG]

Yeah, 12.6V is my expectation as well. I was thinking maybe the battery never got a full recharge after coming back from the dealer, so I took a good drive yesterday. The voltage gauge showed around 14.8V to 15V (and more once in awhile) throughout the drive, so it seems like the system was trying to charge the battery. After shutting the car off yesterday afternoon, the battery was at 12.7V. Great. This morning? Under 12.1V. I don't have any aftermarket electronics that would account for an unusually high drain. So, I think the battery is on its way out. New AntiGravity battery and accessories on the way, hoping that clears up the error message.

 

[DRIVEN]

Did it ?

 

[Angrey]

Be cautious about diagnosing the issue based off system voltage readings. The Ford BMS system is wildly over complicated (thanks to the EPA) and depending on all sorts of inputs and conditions, it will vary from 12.7/12.8 to as high as 14.2-14.4.

The rpms you're at, what the computer THINKS the charge state of the battery, etc, all have an effect on what the charging system tries to do in order to save energy/efficiency or re-charge the battery.

 

[ChipG]

I based it primarily off of voltage readings at the battery via multimeter - 12.7V immediately after a drive, 12.1V the next morning after sitting. New AG battery arrives Saturday, we'll see if that's correct.

 

[Egparson202]

What a pain. I’ve had similar issues, @ChipG. And gone through the same steps. Mine’s healthy at present with a fresh alternator and an ATX-20-HD. Because it’s stored in a rental storage space I can’t run a battery maintainer. So, instead I’ve opted for a quick disconnect. No more drain, no problems since. But with these cars, I’m still wary.

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