17.7 volts from factory alternator, WTF??!!

[stones 10+ year member]

Just put a brand new battery in my car (800 CCA Energizer) and something strange happened, the volt meter on the dash is showing a high 17 volt reading. A check with a digital multimeter confirmed this showing 17.5 to 17.8 at the battery terminals with the engine running and 12.7 volts with the engine off.

The car is running fine but I fear the high voltage may cause damage to the new battery, is this a voltage regulator failure?.

Its a 1988 Dodge Aries with a 2.5 litre engine and a stock 85 amp alternator. This started moments after installing the new battery and firing the car up for the first time, the system read 14.5 volts with the old battery that wouldn't hold a charge.

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[JimJ 5,000+ posts]

Sounds like the regulator's going bad...

 

[tommyk90 5,000+ posts]

Sounds like the regulator's going bad...

x2

I'd get that alt out of there ASAP because you may fry the vehicle's electrical system.

What does your battery sit at when the car is off?

 

[Johnny Drama 5,000+ posts]

x2
I'd get that alt out of there ASAP because you may fry the vehicle's electrical system.

What does your battery sit at when the car is off?

12.7v

I definatly agree that you need to get the voltage reg looked at before it causes serious damage.

 

[squeak9798 5,000+ posts]

Yeah, definitely avoid running that alt until you get it looked at.

That high of a voltage could seriously screw over your electrical system.

 

[stones 10+ year member]

Thanks for the info, I have a spare alt I can throw in tommorow morning.

Nice thing about K-cars are the parts are plentiful and dirt cheap.

 

[stones 10+ year member]

Popped in the spare alt, system is at a healthy 14.7 volts now.

Changing an alt in the dark when its -4 F sucks balls.

The spare is a smaller 75amp while the buggered one is a Bosch 90 amp according to the case markings, im gonning to see how much it will be to fix the original on monday.

 

[lilmaniac2 5,000+ posts]

HO alt time for you

 

[Mynameismcgyver 10+ year member]

or its just charging the battery because its not fully charged..Could b wrong.

 

[88Vette 10+ year member]

Hopefully you can find an alternator shop that can rebuild your 90 amp or beef it up some on the rebuild.

 

[Eldorado 5,000+ posts]

That alt is kinda of a pain to get out.

I chewed up a belt on my moms acclaim because of that stupid thing.

Stupidest belt tensioner ever made

 

[stones 10+ year member]

Turns out I only need to replace a small module on the back that only costs 30 bucks. I don't need an HO rebuild because the system is no more than 500 watts RMS so the factory spec will work fine (big 3 already done as well).

I must say that the belt tensioner design does leave quite a bit to be desired.

 

[Eldorado 5,000+ posts]

That module went out on mine as well.

I had to fiddle with the wire to get a charge

 

[audiolife 5,000+ posts]

good job in specing it out before getting something you dont need

 

[squeak9798 5,000+ posts]

Glad to see it was a simple fix //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

To bad that little $30 part going out could have totally screwed over all of the electronics in your car //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif