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Guest Message by DevFuse

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voltage question

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8 replies to this topic

#1 dragonwingsubaru


    Subaru Nut

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  • englewood

Posted 28 February 2005 - 01:08 AM

i dont happen to have a voltometer right now so i cant be completely accurate on voltage but on my inside gauge it pretty much constantly reads at the 18 or above area, and i have noticed that when i am running the rpm's higher the headlight are much brighter than normal, its like the low beams are about as bright as a high beam. im wondering if there is a difference in the alts from an 87 automatic 4x4 wagon and a 85 manual 4x4. bboth cars have the power windows and whatnot so i would assume they would run on the same voltage. or does there happen to be a voltage regulator somewheres in the engine bay and if so where is it , that might be bad. dont get me wrong more voltage is good but im worried about 2 much messing something up. it will still hold about on the 17 with the lights on and the heater up and the rear defroster on with the car idleing at about 600 rpm so im really wondering if something is gonna melt soon because of this. oh btw the alt was on the motor from my 87 parts car, that i put in the 85

#2 Ross


    Can't be bothered

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Posted 28 February 2005 - 01:11 AM

Yes, your voltage regulator is probably bad, it is inside your alternator.
Too high voltage (above 15v or so) is very bad, and can burn out a whole list of stuff.

#3 dragonwingsubaru


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  • englewood

Posted 28 February 2005 - 01:17 AM

hmmm sounds like i might wanna pull it off and get it tested then the car the motor was in sat for like 4 to 6 months so i guess it could have gone bad in that time

#4 hooziewhatsit


    I fix old cars

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Posted 28 February 2005 - 01:45 AM

yep, I'd get it tested and (most likely) replaced soon.

I just replaced the alternator in one of my cars. It was putting out about 19v. The lights would really dim when I popped into neutral while driving.

After burning out a few headlights I finally got smart and got another one.

#5 Snowman


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  • Haines

Posted 28 February 2005 - 01:52 AM

Don't run it with that high of voltage. It can damage all sorts of electrical/electronic components.

Generally, the system voltage on most vehicles while running should be 13.5-14.5 volts. More importantly, the difference between the voltage reading with the engine running should be no more than 2 volts or so above the reading with no loads on after the vehicle has sat overnight (that's true open circuit voltage). Since OCV should be 12.5-12.7 on most batteries, charging voltage should be below 15 for sure.

#6 85Sub4WD


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Posted 28 February 2005 - 11:02 AM

I recently blew up my battery after my alt. shot 18 volts for a period of about 1/2 an hour - I was in a remote area, and could not pull over, so I had the pleasure of going down a mountain at 35mph in 5th gear with an 18-wheeler on my tail

Replace your alt. ASAP before you grenade your battery.

#7 dragonwingsubaru


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  • englewood

Posted 28 February 2005 - 11:09 AM

i have at least put 24 hours of driving into it since i got it all together, so im suprised that it hadnt blew up the battery yet from what you guys are saying, and since its a brand new batt i really dont want it to do that, if the rain stops im gonna take it off today and get it tested, thanks for the info guys

and yeah i blew out both of my high beams already, i just thought it was because they are the same lights that were already in the car that has been sitting for who knows how long

#8 85Sub4WD


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Posted 28 February 2005 - 11:13 AM

My battery was 5+ years old when it blew (when I say that I mean it shot acid ALL over under my hood - I now have to do some serious repainting). Given my battery's age it may have already been on its way out - and that may have been why it reacted so violently.

The 18 volts was the straw that broke the camel's back.

#9 exister99


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Posted 01 March 2005 - 04:16 PM

You can also find voltage regulators and graphite brushes at partsamerica.com in case you are handy with a soldering gun.

And yes, definitely get the regulator fixed before you nuke the battery!

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