Fish Chris Posted December 28, 2011 Report Share Posted December 28, 2011 Man, I really hate to have some $#!+ like this start on me now But it seems that either my alternator (stock F150 alt, puts out like 143 amps I think) or my battery, basically a re-branded Odyssey gr31, is starting to give out. I do have an aftermarket voltage gage, so it's easy to watch. But basically, while before just having the truck idling, was enough to keep my voltage to 13.7, sagging maybe only to 13.2 when beating the $#!+ out of my system. But now, when idling, it can barely hold like 12.8, no stereo at all ! The only way I can keep it to 13 volts with the system playing, is when driving.... especially on the freeway. I'm guessing alternator ? Batt would be cheaper, so probably not that, huh ? Fish PS, I used to have an old auto electrical guru friend, who could take any alternator, rewrap, and rebuild it, and make it put out 30 to 60% more juice. He rebuilt an old Cadillac alt for my Chevy S10 Outlasted the truck ! Can this still be done with newer alts, and these computerized beee-otches we drive now ? Link to comment Share on other sites More sharing options...
Mad_Mike Posted December 28, 2011 Report Share Posted December 28, 2011 Well, test the alt. Start the truck up and pull the positive off the battery, stick a volt meter to it and see if it's giving out enough voltage. If it is putting out enough, then it's your battery robbing the alt's power. PS: This method of testing can be risky.. so do it at your OWN RISK. The risk is voltage spikes in the system that can possibly destroy some circuitry in the truck. If you don't feel comfortable doing it, then take the alt to your local parts store and have them test it for voltage. Or, have the battery load tested. Link to comment Share on other sites More sharing options...
Guest DC Power Kyle Posted December 28, 2011 Report Share Posted December 28, 2011 Don't pull the positive off... You can blow the alternator by doing so.. Is the charge light on? Have you put your battery on the charger? So what year f150 and what motor Link to comment Share on other sites More sharing options...
Fish Chris Posted December 28, 2011 Author Report Share Posted December 28, 2011 It's an 08' F150, with a 5.4L motor. Not to sound stupid, but why would I put the bat on a charger ? If everything was working correctly, that wouldn't be needed. If something were bad, that charging from an external source might last about 5 minutes, right ? Hmmmm, Fish Don't pull the positive off... You can blow the alternator by doing so.. Is the charge light on? Have you put your battery on the charger? So what year f150 and what motor Link to comment Share on other sites More sharing options...
ALPINE408 Posted December 28, 2011 Report Share Posted December 28, 2011 sounds like the bat to me since you are still getting voltage while driving if your bat has a bad cell it will allways pull amparge never charge and pull your voltage down but im not alt guy so lisen to dc power edit putting the batt on a charger then putting a small load on it if it drops fast its the batt thats why its a way of checking your batt with a charger Have you ever had your woofers blown? Link to comment Share on other sites More sharing options...
TeamHT Posted December 28, 2011 Report Share Posted December 28, 2011 :ohmygod: @ Mad Mike Tell me...does this smell like chloroform to you? Link to comment Share on other sites More sharing options...
Guest DC Power Kyle Posted December 28, 2011 Report Share Posted December 28, 2011 Reason why I say put it on the charger is if the battery is 50% capacity then all you need to do is charge it to start seeing higher voltage. If you have a costco nearby, go grab a cheap kirkland battery, put it up front and see if your voltage is where it's supposed to be. The PCM in the Ford's is pretty damn smart and would throw a charge light if there was an issue. Check it with a DMM at the battery and see if you're getting the same reading as your volt meter. Link to comment Share on other sites More sharing options...
n8ball2013 Posted December 28, 2011 Report Share Posted December 28, 2011 batteries do require topping off sometimes. THERE IS NO BUILD LOG! 1998 Chevy Silverado ext cab Alpine CDA-9887 4 Team Fi 15s 2 Ampere Audio TFE 8.0 2 Ampere Audio 150.4 3 Digital Designs CS6.5 component sets Dual Mechman 370XP Elite alternators inbound! 8 XS Power d3400 6 XS power d680 Second Skin Stinger Tsunami Wiring Sky High A Real Voltmeter not a piece of shit stinger. Link to comment Share on other sites More sharing options...
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