Voltage fluctuation

[partswiz]

Hi Guys,

Another question...I just want to confirm that it is normal to see voltage fluctuating between 12 or 12.5 up tp 14.5. Seems weird to me but maybe that is the norm on these newer cars...

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[Evolvd]

Hi Guys,

Another question...I just want to confirm that it is normal to see voltage fluctuating between 12 or 12.5 up tp 14.5. Seems weird to me but maybe that is the norm on these newer cars...

12.5 is steady state of the battery (really it’s 12.7 but the digital gauge isn’t exact). 14.5 is when the vehicle is operating and the alternator is charging the battery or otherwise operating under a load.

 

[partswiz]

12.5 is steady state of the battery (really it’s 12.7 but the digital gauge isn’t exact). 14.5 is when the vehicle is operating and the alternator is charging the battery or otherwise operating under a load.

Great info, thanks! Is it normal though to see it at 12.5 while I'm driving?

 

[rjoseph1960]

Hi,
I have a 21 Gt Vert, and I see the same thing on my car. I believe Ford is reducing the Battery's Charge rate on the battery due to High Under hood temperature. This will prevent boiling the acid, and drying out the battery. For piece of mind, I plug in Ford's Battery Tender everytime I park the car, my car will sit for a week at a time.

Bob

 

[Evolvd]

Great info, thanks! Is it normal though to see it at 12.5 while I'm driving?

As long as your battery is holding a charge yes. If the battery is fully charged and you’re not using high load systems like AC, full radio volume, high beams, etc the BMS will reduce voltage on a 100% battery

 

[AvalancheSVT]

Hi Guys,

Another question...I just want to confirm that it is normal to see voltage fluctuating between 12 or 12.5 up tp 14.5. Seems weird to me but maybe that is the norm on these newer cars...

this is the way its been for decades. alternators have internal voltage regulators, pcm does stuff with it, heat changes things, blah blah.

there's a reason most cars don't have gauges that show details like ours

people worry too much.

 

[Vlad Soare]

Great info, thanks! Is it normal though to see it at 12.5 while I'm driving?

Sometimes. But not for a long time.
These cars use an intelligent, adaptive charging strategy, controlled by the BCM (body control module) using a battery monitoring system - the BMS.
When the battery has been fully charged for some time and you're still driving, the BCM will lower the voltage a bit, in order to avoid overcharging and overheating the battery. This should not last long. You may even see 12.0 volts for a short while. If it only happens under light throttle, and the voltage raises visibly while engine-braking, then drops again as soon as you touch the gas pedal, then it's all right, it's just the BMS doing its job.

 

[WItoTX]

This is normal. Several thread posted about this.

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