Charging issues

[Schizo]

Morning, has anyone experienced poor charging after idling for a while? I started out on a road trip last night and needed to sleep at a rest stop for almost two hours. I left the car running and I noticed when I got back on the road the voltage is sitting at 13.0 when it's usually at 13.9-14.00... The weird part is if I let off the gas and coast it goes back up to 14.00.


2013 SHO non PP


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[SHOdded]

Idling will slowly suck power out of the battery, as the alternator isnt producing max power at that rpm. Plus if the battery is original to the car, you likely need to replace it anyway.

 

[krewat]

The cooling fans, and the AC clutch (if it was on) will suck enough voltage that when idling, a marginal alternator might not supply enough to keep the battery at 100%.

As an experiment, get a digital volt meter, set it to DC volts, and check the battery after the car has been off for an hour. It should be around 12.6 volts - 12.6 volts is 100% charged for a typical lead-acid car battery. If it's below 12.3, or even worse, below 12, it's time to replace it. The alternator might hit it's max output at idle because it's trying to charge the battery while the cooling fans and other stuff are also drawing.

Do the interior lights (something incandescent, not HIDs or LEDs) dim when it's idling?

Report back the battery voltage

 

[Schizo]

The cooling fans, and the AC clutch (if it was on) will suck enough voltage that when idling, a marginal alternator might not supply enough to keep the battery at 100%.

As an experiment, get a digital volt meter, set it to DC volts, and check the battery after the car has been off for an hour. It should be around 12.6 volts - 12.6 volts is 100% charged for a typical lead-acid car battery. If it's below 12.3, or even worse, below 12, it's time to replace it. The alternator might hit it's max output at idle because it's trying to charge the battery while the cooling fans and other stuff are also drawing.

Do the interior lights (something incandescent, not HIDs or LEDs) dim when it's idling?

Report back the battery voltage

After about an hour so the battery is at 12.5 V. I'm still on the highway on the way to the Ford dealership in Dunn North Carolina. if I stand on the pedal the voltage drops all the way to 12.7v under wide-open throttle


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[krewat]

After about an hour so the battery is at 12.5 V. I'm still on the highway on the way to the Ford dealership in Dunn North Carolina. if I stand on the pedal the voltage drops all the way to 12.7v under wide-open throttle

Is this using a hand-held digital volt meter, or does your car have a volt meter in it? 12.5 is fine or at least good enough

The fact that it drops under wide-open-throttle means either the belt is slipping REALLY bad, or the alternator is toast - and "toast" is a technical term - LOL

I can think of a few reasons that the alt would stop charging at high RPMs, it all points to the alt being bad.

Make sure you tell them the alt dies when you floor it.

 

[krewat]

You know, I'm not so sure that the alternator shutting off at WOT is a bad thing, the PCM might do this on purpose.

 

[Schizo]

Their conclusion is that when I left the car idling it overheated the alternator therefore it's output was decreased... More or less I feel that they could not duplicate the problem therefore that was their generic answer. They also discovered multiple leaks which is all covered under the powertrain warranty


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[SHOdded]

Overheated to the point of failure/replacement? What leaks did they find, did they provide a list by any chance?

 

[Schizo]

Overheated to the point of failure/replacement? What leaks did they find, did they provide a list by any chance?

I found something that might shed some light..
Battery management: Smart Charging
http://www.ecoboostperformanceforum.com/index.php?topic=5062.0


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