98 eclipse blowing up battery. charging at 18v

[mplacek27]

i have a 98 eclipse that is making 16.5 volts at idle and 18 volts revved. the battery was checked and it is good. all grounds are good. alternator was tested and it is also good. the alternator on it is not volt reg in the alternator. i was told it is regulated in the ecu but if you go to advanced or napa they sell a voltage reg for it dunno where it goes though. it has a hole and brushes in it. not sure what to do. after bout 5 min of running at this voltage the water in the battery boils and blows the caps off

 

[NeMiZiS]

Mine at idle is around 14.5, it sounds like a electrical issue of some kind.

Have you tried using a different battery? To see if it does the same thing?...
It's just a thought....

 

[shaggyslaser]

Maybe the diode rectifier bridge has blown? Try another battery, and another alternator. Have you tested the specific gravity of fluid inside the battery?

 

[xreaction122]

is it properly grounded?

 

[XLR8]

Our alternators have voltage regulators built into them, autozone units are famous for having them crap out. I have had 2 new autozone ones in a row put out 35 volts after the regulator went. That will melt some wires for sure.

 

[ali]

you need a new alt.

 

[JayRolla]

Yeap alternator is bad. Very surprised the tester didnt fail it. Like stated regulator is not working. Make sure the plug going to the alternator (regulator) has both wires intact. I had one wire break off the plug and it fried the regulator.

I would rather buy a 200,000 mile junkyard alternator than an autopart store crap one. Ive gone through 5 alternators with lifetime warranty in 1 year before. Have gone through 2 180,000 mile alternators in 3 years. I finally got a 75amp alterstart.com alternator and it works great. It also has liftetime warranty but it hasnt failed yet.

 

[DSM1G90]

AUTOZONE!! Like the chubby mouthy chick that couldn't shut up that you had on a blind date: HORRIBLE !!

Yep, regulator inside went to hell frying everything up attached to it.

 

[RayBan GST]

change your alternator dont wait to change and try another battery just change your alternator ( you will find used one in the junk yard for about 100 USD )

 

[mplacek27]

so i put in a new battery and didnt fix anything. i took the alternator to an alternator shop and the dude told me its not internally regulated its regulated by the computer. not sure about whats going on?????

 

[mplacek27]

ok so i went to the junkyard today and got an alternator and a nother ecu put them in and its still putting out like 19 volts. it will start and be about 14 14.5 then jump to 19 after a min sometimes it takes a couple minutes to jump up. i went over all the wiring i thought could be causing this dident see anything wrong . HELP. not really to sure what else to try. prob a for sale sign soon