M4wd&Fabrications
Projects place => Projects Section => Topic started by: cracker on July 24, 2013, 08:56:25 AM
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Since Big Dogs the battery has been dying in the Jeep.. jump it and drive it a bit and it would be good for a few days.. I figured something was draining it.. last night I jumped it and watched the volt gauge.. it was pegged at 19 for a bit...then dropped to 0 for a bit...then pegged at 19 for a bit... over and over.. Does that mean the Alt is dead?
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Most likely but battery may cause odd issues too. Disconnect the batt with in running and watch.
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I'd try a fresh battery first, or at least a different one from something else.
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start, disconnect, measure alternator output. should be 14.7ish
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ok stupid question.. do I just disconnect the + cable from the battery then put the meter between the + cable and the - terminal of the battery?
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ya
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dont lick anything
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Don't let the hot touch the chassis/ground
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Well jumped it then the meter read about 12.5 between the battery posts, but if i put the probes on the clamps it read 0. Unhooked the positive and it was still 0.
So does that mean it is the alt?
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Rip alternator
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Wait wait wait, it reads 0 on the terminal still hooked to the battery?
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Wait wait wait, it reads 0 on the terminal still hooked to the battery?
yes.. if the probes are directly on the posts it read 12+, move to the terminal clamps(still attached to battery) and it went to 0.
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clean your posts and clamps you should still have 12 at the clamps if your battery is full
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Posts and clamps should be the same if everything is hooked up. Clean 'er!!
Tapatalking in traffic
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Yeah try it again. I don't think posts could possibly be that corroded.
Regardless your alt is hosed.
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now I remember having an issue getting the neg terminal tight, so I stood a washer between the post and the teminal.. maybe that is corroded enough to kill the connection. I just wish I had more than 5 minutes to look at this thing at a time.
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spent another 5 minutes tonight.. might have found a culprit or maybe just another issue. followed a cable from the + terminal to the junction box, popped the cover off and found that terminal half corroded through.. touched it and it was pretty weak.. and broke apart. Now I gotta figure out how to get the nut off so I can re-attach the wire. Soaked it with PB and will see if I can get it loose.
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spent some productive time on it last night..
I was finally able to hold the top of the stud with a pair of plyers while turning the nut to get it loose.. used a bit of bush-mechanicry to squeeze the broken tail under the existing plate and nut to re-make the connection.
jumped it and got it started
did some more volt gauge test and found I was just not digging into the clamps enough with the probe to get a reading before, so it does nto matter where I put the probe I get a reading
but the dash gauge was still jumping randomly between both pegs while the handheld volt meter just jumped between 11 & 13
The jeep ran fine when I remove the positive terminal from the battery so I think the alt is still good, volt meter still wavered between 11 & 13 between the positive cable and the neg battery.
Let the jeep sit idling for about half an hour, shut it off and battery did not have enough to turn back over..
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Picture of broken terminal before bush mechanicry
(http://img.tapatalk.com/d/13/08/31/be5ynave.jpg)
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I'm still voting alternator. should be getting 14.7ish out of it and it shouldn't fluctuating like that. may have fried your batt too when it was pegged at 19.
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when the dash gauge is pegged at 19 the handheld is never over 13... I am thinking there is ground issues
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I threw an extra battery i the passenger seat and I jumped her this morning... let it sit and run for half an hour, shut off and barely had enough juice to crank.. jumped her again and drove to work.. a bit nervous since the inspection ran out in June.. got here shut her off, txt'd the wife that I made it safe and then turned the key and she fired right back up.. gauge jumped around a bit early in the drive but then settled down and read 14V the rest of the way.
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Better than my Eagle! Drove St. Michael to work yesterday, cranked solid at home. Wouldn't start when I had to go to campus, so I had to walk home and drop the trailer.