I have a 2008 yukon with the stock alt and a optima yellow top and the big 3...my electrical has always been enough for my setup,im only running around 1300w but a week ago i left my light on and the next day my battery was drained...i jump started it...but now my voltage at driving and iddle drops down to 13v...before it ran around 13.9-14.7v...i used my multimeter and 13v is whats the alt is putting out...my battery with the truck off is 12.6v.:.here is the funny part...if i turn on all the lights and the front and rear AC the voltage jumps up to 14.9...is my alt dying on me or is it the batt?

Bad cell in the battery would be my answer.

Never let your alternator charge a drained battery. That is the fastest why to ruin it. Your problem sounds like the battery.

Dam it i was hoping it was the alt...looking for an excuse to buy one...here is a second question...if i buy a HO alt, say 300amp+ how many batts should i put...im keeping my current system so 1300w is what i need to power...i only use it while driving and my budget is around $800

you are thinking about buying a better alt to power 1300w of power?

Not necessary at all.

All you need is a single battery in the back to act as a buffer for current demands.. that's it.

Run 1 run of power AND ground from front to rear to sustain equal voltage from front to rear.

Im also powering air suspension, train horn,

So i just purchased a brand new deka intimidator for my truck and its still dropping voltage...same thing as before...i rechecked my big 3 terminals and everything is good...it drops down to 12.5 at iddle

you cannot drop below battery rest voltage unless you are pulling current.

You need a DMM and Ammeter. Two things everyone should have.

Either that or install a SMART Monitor in your car.. Either way.

But from the looks of it right now, 12.5v is WAY too low for a G31.

You now need to purchase an AGM battery charger and top this battery off or you'll always have problems.

Next, you will need to clamp your alternator's power cable and see how much current it pulls on a burp(quick session of bass) as loud as you can go.

If the alt's output per engine rpm is nothing what it should be(lot lower), then it would sound like part of your rectifier is damaged.

Is your belt in good condition? Tight enough to not slip?

Well i did squirt some soapy water like 2 weeks ago..just to get rid of some squeek...

I do have a dmm and the read on the alt terminal is the same as the batt...

All this started after my battery died and i jump started it..when i turn on the ac and all the interior lights it jumps back to 14v+

Can't play the speculation game.

You need tools to find the problem.

Otherwise, we can just go down a list of things to start replacing..

Cost of tools is a lot cheaper and sometimes free if autozone knows what they are doing.

well if its pcm controlled that makes a littble bit of sense.

It see's the voltage dropping and compensates for it.

But the idle voltage is bad.

Oh i forgot to add this...the fuse holder has begun to slowly melt...and the wire from batt to alt gets supper hot...

Has happened to me plenty of times.

make sure your grounds are good

Do you have just wire or are they crimped at teh end?

If just wire crimp them to some connectors to help dissipate some of the heat.

Actually when i did the big 3 i Crimped the connectors and i sodered the ends...all 0 ga wire...I put in a new 300a fuse and i disconnected the system fuse...

Oh i forgot to add this...the fuse holder has begun to slowly melt...and the wire from batt to alt gets supper hot...

What fuse holder are you using?

Melting blocks can only happen from resistance due to a poor connection.

If it's a Knukonceptz block then that's why your voltage is bad, plain and simple.

IF it's not their block, then you need a REAL block, either custom built or from someone who knows what conductivity means such as Stinger or Xscorpion.

You have to get rid of that block now anyhow because it's already created resistance in it that cannot be fixed.

Buy a new fuse holder.

Add more and bigger washers to the fuse holder.

Clean the ends.

Check the voltage before the fuse and after it, with the system turned up a bit.

If its melting im sure you will have a lower voltage after the fuse.

edit:

I think i bought a cheap 1 and just put in bigger bolts.

But if you run multiple runs you will have less of an issue as well.(inefficient but ehh)

Edited February 8, 201312 yr by djjdnap

Its a brand called titanium...it cost me around $12 plus another $8 for the fuse its self..i removed the fuse going to the system and its not losing volts...im gonna drive around and see if it keep on doing it...im gonna invest in some new wire And some quality fuse blocks and fuses...

Well, only knukonceptz is the only one i know who is retarded..

Can you post a link up to the fuse holder?

I would get the alternator checked. If the alt's fine and the battery is new i would bet its the belt is sliping. Is it a slowly going down voltage or like go from 13.6 and drops to 12.5 really fast?... What we all are trying to say is in a Technicians terms "Troubleshoot" limit the possibilities of all the problems that can occur. I have a major belt problem on my wagon still a ongoing problem :(/>((((

Edited February 8, 201312 yr by Dictator

Fuse block

http://www.titaniumpower.com/Details.aspx?id=20078301546406417043178

Fuse

http://www.titaniumpower.com/Details.aspx?id=20078301554576417043178

Wire

http://www.titaniumpower.com/Details.aspx?id=2007961443346417043178

I would get the alternator checked. If the alt's fine and the battery is new i would bet its the belt is sliping. Is it a slowly going down voltage or like go from 13.6 and drops to 12.5 really fast?... What we all are trying to say is in a Technicians terms "Troubleshoot" limit the possibilities of all the problems that can occur. I have a major belt problem on my wagon still a ongoing problem :(/>/>((((

I turn on the truck and the voltage is 14.9...it takes around 3-5 minutes to drop down to 12.9...if i turn on the ac and the dome lights it jumps to 14.9 volts in 2-3 minutes...fuse block melted ...

I would get the alternator checked. If the alt's fine and the battery is new i would bet its the belt is sliping. Is it a slowly going down voltage or like go from 13.6 and drops to 12.5 really fast?... What we all are trying to say is in a Technicians terms "Troubleshoot" limit the possibilities of all the problems that can occur. I have a major belt problem on my wagon still a ongoing problem :(/>/>/>((((

I turn on the truck and the voltage is 14.9...it takes around 3-5 minutes to drop down to 12.9...if i turn on the ac and the dome lights it jumps to 14.9 volts in 2-3 minutes...fuse block melted ...

This sounds exactly like something happened to me extremely recently. If I revved above 4k rpm the charge would pick back up a second and remain charging for a few then drop back down again to battery voltage. I believe the issue to be a bad regulator in the alternator. My new alternator does not have this issue at all

Just got the email from mike singer and he gave me a great price for a new alt...whats the feedback on his alts?

Well, do not assume that there is a single solution to every problem being experienced right now.

I'm focused on this fuse block melted.

I looked at the block, appears just like any other..

I'm assuming their wire is of adequate performance, i just never heard of them before.

For that block to be a wire insert, are you sure that wire is EXTREMELY tight in there?

It should be so tight that you physically cannot pull it out. IF you can, there's your problem.

Another reason for melting is sporadic grounding issues that are too fast for the fuse to notice(which i doubt anyways)

Also, Check the fuse screws. IF the screws holding the fuse down is not rock solid, that's another reason!

see, if the fuse isn't popping and it's a 300a fuse, then the current making the block melt is under 300A.

300a is not enough to cause this to happen. If it were, then they wouldn't make them capable of holding those types of fuses because 1/0 wire is capable of transferring that current so the fuse block not should, but does have the same or better capability.

From the alt, to the fuse block, to fuse, to other side of fuse, to other side of fuse block to entire battery terminal AND POST of battery and ground at batt terminal AND POST and frame ground, i'd check ALL for loose connections or for non-measurable variables or those with resistance.