Overcharging problem...battery hissing!

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Apr 8, 2008 | 07:32 PM

custom1106

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From: Phoenix, AZ

Overcharging problem...battery hissing!

I picked up a '77 F250...it seems as though the alternator is overcharging the battery....up to 18 volts at times. Even after I put a new regulator on the truck....it still does it. Time to replace the alternator or...?

Apr 8, 2008 | 07:40 PM

fmc400

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From: Austin, TX

How does the wiring between the alternator and regulator look? The connector for the regulator is often victim to debris and corrosion due to its location. High resistance in the wiring and connections between the regulator and alternator could cause the regulator to "sense" a lower battery voltage and cut the field faster to compensate thereby overcharging the battery.

Apr 8, 2008 | 10:50 PM

custom1106

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Just "traded" this lifetime warranty alt for a new one and I'm having the same problem. While I was swapping out the alt, I checked/cleaned all grounds and connections on the battery/solenoid/alt/reg. I now noticed that as soon as I turn the key to the on position, without the truck running, the ammeter pegs out to full charge and has an audiable high pitched whine. Checking the battery with my meter while the truck is running I still get 15 to 18 volts.

Apr 9, 2008 | 12:15 AM

Franklin2

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Check the yellow "a" wire coming off the regulator. Make sure it's tied good to the battery +. This is the wire the regulator uses to monitor the voltage in the system.

Apr 10, 2008 | 12:52 AM

custom1106

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Check out this video of my amp gauge....very fun at night with pulsing headlights.

Video of amp gauge - Photobucket - Video and Image Hosting

Apr 10, 2008 | 05:36 PM

Franklin2

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So what's your next move? Pulsing headlights is a sign the regulator has lost it's ground. Run a wire from one of the reg mounting bolts to the bat neg, and see if that helps it.

Apr 10, 2008 | 07:41 PM

custom1106

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From: Phoenix, AZ

directly grounding the regulator was the first thing I did.....claened all underhood grounds. Just found a taped up mess by the bottom of the battery that someone has hacked together. I picked up a GM alternator, I'm tired of all the extra wiring. I'm just looking for some simple, reliable charging.

Thanks for the info...much appreciated!