tdc3187 Posted December 30, 2011 Report Share Posted December 30, 2011 So tinkering around a little today I found the post from alt to battery. Grounded my dmm to battery, positive at the alt post and it appears I'm getting normal voltage. Turned the car off; dmm on both posts on the battery; 11.7 Car on at the battery post yields about the same voltage. I don't know a ton about batteries and alts, but I guess I'm going to pull the battery out, put it on the charger. If the battery doesn't come up above 12.x, I guess the battery is bad. Is this correct reasoning? Quote Viper 5902, big 3, 1/0 Rockford wiring, 2 xs d3100, mechman 300a, pioneer avic-z1, 2 dc 12xls, Rockford t2500.1bdcp, Rockford t1000.4ad, Rockford t2 6.5 comps, damplifier Build log: http://www.stevemeadedesigns.com/board/topic/102584-carbon-fusion/ Link to comment Share on other sites More sharing options...
cal Posted December 31, 2011 Report Share Posted December 31, 2011 yea try charging the battery and then go to local auto parts and do a load test before the install also make sure the terminals are clean. i had a similar issue the alt was charging but i had some battery acid leak and it built a layer of corrosion arround the terminals so my back aux battery was ok but my front was not charging . Quote Link to comment Share on other sites More sharing options...
tdc3187 Posted December 31, 2011 Author Report Share Posted December 31, 2011 (edited) Checked the charger this morning before work it was reading 13.4 volts. I'll continue to let it charge until tonight. If it was the battery and not the alt; why wouldn't the battery start to charge with the car running? It just drops volts at a steady pace. Sent a message to mech for a price for a xs for under the hood Edited December 31, 2011 by tdc3187 Quote Viper 5902, big 3, 1/0 Rockford wiring, 2 xs d3100, mechman 300a, pioneer avic-z1, 2 dc 12xls, Rockford t2500.1bdcp, Rockford t1000.4ad, Rockford t2 6.5 comps, damplifier Build log: http://www.stevemeadedesigns.com/board/topic/102584-carbon-fusion/ Link to comment Share on other sites More sharing options...
tdc3187 Posted January 1, 2012 Author Report Share Posted January 1, 2012 Charged battery for 24 hours. Took it off the charger around 14.3 and it dropped to 13.4ish. Stuck it in the car and cranked the engine and it dropped to 12.1 and stayed in that area. I am going to run by discount auto tomorrow to pick up a clay bar kit and jumper cables. I'll try to disconnect the battery and use jumpers to use one of my xs d3100s. I am still worried that my alt isnt working correctly. But that is for another day I guess. Quote Viper 5902, big 3, 1/0 Rockford wiring, 2 xs d3100, mechman 300a, pioneer avic-z1, 2 dc 12xls, Rockford t2500.1bdcp, Rockford t1000.4ad, Rockford t2 6.5 comps, damplifier Build log: http://www.stevemeadedesigns.com/board/topic/102584-carbon-fusion/ Link to comment Share on other sites More sharing options...
tdc3187 Posted January 5, 2012 Author Report Share Posted January 5, 2012 Had the battery load tested today, and it tested good. So I'm lost. I put the stock battery in the car, hooked up a d3100 that I have in my garage with a set of jumper cables and it's the same thing. Resting voltage at the battery terminals is around 11.x, but the voltage at the alt terminal is 14.x. Please help me, I have a loaner car now but need to return it by the end of next week and I'm getting nervous Quote Viper 5902, big 3, 1/0 Rockford wiring, 2 xs d3100, mechman 300a, pioneer avic-z1, 2 dc 12xls, Rockford t2500.1bdcp, Rockford t1000.4ad, Rockford t2 6.5 comps, damplifier Build log: http://www.stevemeadedesigns.com/board/topic/102584-carbon-fusion/ Link to comment Share on other sites More sharing options...
MIKE-2U Posted January 5, 2012 Report Share Posted January 5, 2012 the voltage at the alternator charging post is 14.3 while running correct? that means alternator is working fine. once you shut the car off that post should read what the battery reads. as far as the 11.75 volts. if it still starts the car than should be good. my car sits outside and my voltage reads 11.5 somedays and still cranks right up. How old is the battery? the fact that it passed the load test tells me it must be good. But depending on age, eh , you may wanna think about replacing it soon. Quote 2006 Jeep Grand Cherokee LaredoPioneer AVH- 3200DVD2/0 Flex-A-Prene Welding Cable (2) Fully Loaded Fi Sp4's dual 1-------> My YouTube Channel <------- Needs more power those woofers will laugh at that turd Link to comment Share on other sites More sharing options...
tdc3187 Posted January 5, 2012 Author Report Share Posted January 5, 2012 The battery was purchased 8/10. It will crank by key, but thru my viper it will crank then shut off within one minute, then recrank, shut off, recrank.... Even with a charged d3100 on jumpers the charging light illuminates on the dash and voltage at the terminals is sub 12.x Quote Viper 5902, big 3, 1/0 Rockford wiring, 2 xs d3100, mechman 300a, pioneer avic-z1, 2 dc 12xls, Rockford t2500.1bdcp, Rockford t1000.4ad, Rockford t2 6.5 comps, damplifier Build log: http://www.stevemeadedesigns.com/board/topic/102584-carbon-fusion/ Link to comment Share on other sites More sharing options...
tdc3187 Posted January 6, 2012 Author Report Share Posted January 6, 2012 (edited) 1/0 from alt post to battery; voltage back to normal. There has to be a fuse that is messing up the voltage somewhere on that line. Should I fuse that 1/0 (alt to batt) with a 300 to be on the safe side. And should I add a second 1/0 since the factory wiring is messed up? Edited January 6, 2012 by tdc3187 Quote Viper 5902, big 3, 1/0 Rockford wiring, 2 xs d3100, mechman 300a, pioneer avic-z1, 2 dc 12xls, Rockford t2500.1bdcp, Rockford t1000.4ad, Rockford t2 6.5 comps, damplifier Build log: http://www.stevemeadedesigns.com/board/topic/102584-carbon-fusion/ Link to comment Share on other sites More sharing options...
Guest Posted January 6, 2012 Report Share Posted January 6, 2012 if the battery rests at under 12.6 without being in the car, after being charged, its bad. although its strange that these symptoms pop up when the battery is a few months old. what kind of battery is it? Quote Link to comment Share on other sites More sharing options...
tdc3187 Posted January 6, 2012 Author Report Share Posted January 6, 2012 Ford motorcraft I think. Quote Viper 5902, big 3, 1/0 Rockford wiring, 2 xs d3100, mechman 300a, pioneer avic-z1, 2 dc 12xls, Rockford t2500.1bdcp, Rockford t1000.4ad, Rockford t2 6.5 comps, damplifier Build log: http://www.stevemeadedesigns.com/board/topic/102584-carbon-fusion/ Link to comment Share on other sites More sharing options...
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