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Battery Dies Overnight (Alt or Batt?)


matt 2k12

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Hey guys. I took a quick video and a few pictures of my alternator and idler pulley. Our company mechanic told me he thought it was the bearing in the idler pulley going out and squeaking. I took some pictures for you to see. He says that could cause the alternator to not charge correctly. Or maybe I am looking at 2 seperate problems but to me they seem related. The squeaking is hard to hear or differentiate and it sounds a little different on video than in real life but you get the idea. Please let me know what you think about all this. I still havent had a chance to do a draw test.

Video of squeaking sound - https://dl.dropboxusercontent.com/u/80070250/VID_20130906_105350_620.mp4

Photos of Idler Pulley - https://dl.dropboxusercontent.com/u/80070250/IMG_20130906_105457_203.jpg , https://dl.dropboxusercontent.com/u/80070250/IMG_20130906_105507_124.jpg

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I can't watch the video but I just replace mine on my duramax.Pull the belt off and spin both of the idler pullies I bet one or both are almost seized and hard to spin.I am not sure why your battery acts the way it does though.

Replace both pullies if one is bad they are under $30 bucks each.

 

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Hard to tell from the video, I would try a battery charger on a medium rate overnight to fully charge the battery then take it to an autozone that can load test the battery and electrically test the alternator. Check the pulleys as recommended above, could be part of the problem, but wouldn't think it would stop the charge process all together.

 

Good luck, hopefully you have the weekend to work on it.

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If you have access to a charger I would slow charge it and bring it up to like 13.3. Leave it and it should settle at 12.8. When I say leave it I mean out of your truck and overnight. If the battery holds charge you have some other issue that is drawing it down over an extended amount of time. If you don't have a charger check voltage at the end of your day pull your battery. If its still dying overnight not being in the truck it's the battery. I had the same issue in my tahoe. I pulled the positive side of my battery terminals and the tahoe died. The alt. was the problem. Hope you get it figured out.

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Well I fixed the idler pulley and when I went to buy it I had them do a batt/alt check and everything came back fine. Cranking amps a little low but still within spec he said. Now it starts up everyday no problems? Didnt have to replace the battery or alternator. I went ahead and did a WOT pull since I hadnt done it in a while and put some charge in there. Seems to be running fine now. Weird. But at least the squeaking is gone. Has anyone ever had the idler pulley affect battery charge?

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Well I fixed the idler pulley and when I went to buy it I had them do a batt/alt check and everything came back fine. Cranking amps a little low but still within spec he said. Now it starts up everyday no problems? Didnt have to replace the battery or alternator. I went ahead and did a WOT pull since I hadnt done it in a while and put some charge in there. Seems to be running fine now. Weird. But at least the squeaking is gone. Has anyone ever had the idler pulley affect battery charge?

It is possible the pulley caused excessive drag on the belt causing it to spin slower and rotate your alternator pulley less.

 

Sent from my DROID BIONIC using Tapatalk 2

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I had my alternator tested and it came back fine as well. It was re tested 4 times that day off the truck and then it was diagnosed as being bad. Just a heads up, just because the test showed it was good on the truck, doesnt always mean it is.

 

 

I have never heard of a idler pulley causing a charging issue.

Edited by Blown 346 (see edit history)
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I have never heard of a idler pulley causing a charging issue.

 

 

I just know on my truck when my pulley froze the belt was dragged over the pulley but I don't believe it affected charging.

Sent from my DROID BIONIC using Tapatalk 2

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It's NOT THE BCM. Go down to auto zone, O'Reilly's, Pepboys, ect. And have them preform a starting and charging test ( they will do it for free ) if either your battery or alternator fail replace them. If everything passes you have what's called a parasitic draw. These are lots of fun it could be anything ( not the bcm / ecm ) that uses electricity. The, cluster a light in the glove box, your stereo. Good luck

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I had a strange issue awhile back, Had a dead battery a couple times, got the battery tested and tested bad so i replaced it. Few days later dead battery, tested alternator, tested bad, replaced alternator. Few days later dead battery, did a parasitic draw test and found out my radio was still pulling power. Now have a new head unit and have been good since.

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