High voltage at battery

Truck has become a weekend only truck as I have bought a daily driver. If it sits more that about 4 days it won’t start. Jump it off and your fine. Jumped it off today and drove it to the store came home and decided I was gonna put a battery tender on it so I don’t have to worry about it. Before I did I checked the voltage at the battery while not running and it’s reading 16.25 and 17.10 while running. Any ideas? Put a new alternator on a year ago.


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wow.. sounds like a regulator problem.. I went thur a few alt from auto zone never again.. get a factory or a real alt builder.. dc power or ?

The one I got was from Autozone as well. I knew better! Looks like this is gonna be a lesson learned kind of deal.


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Stick to motorcraft in my opinion.

superpsd said:

Stick to motorcraft in my opinion.

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Unless you purchase new the rebuilt Motorcraft ones are just as bad

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If the battery voltage while not running was that high, then the batteries themselves have to be bad. Especially if they're dead after sitting for a few days. Batteries can only be cycled to dead a few times before they loose life rapidly.

Use you voltmeter on another vehicle and test your test instrument.

I gotta tell bud. In 30 years of using multimeters I’ve never had this happen. Took your advice and checked 2 other vehicles and bam. Same thing. Changed the battery and we’re back in business. I appreciate the help y’all.


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Glad it was a cheap battery and not the expensive ones.

You and me both but I still need to figure out where the drain is coming from. I’ve had it on a battery tender for about 30 hours now and it’s still showing it’s charging. We’ll see in the morning.


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How old are they?

2 year old motorcraft batteries


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