shorted battery to alternator, now it wont charge

[1meanGTA]

i made another post in the modified 95-01 forum but im thinking that was the wrong place now, so mods please delete the misplaced one is this isnt cool.

i have 2 alternators, one a stock 130a, the other an iraggi 240a. while tightening the nut down onto the charging post on my iraggi, i overtightened and broke off the post. the stock wiring was on the bottom, the 1/0 gauge run that i added from my alt to the battery was on top, and the 1/0 wire touched the casing of the alternator, gave a nasty spark, and actually burned away part of the casing of the alternator. was touching for a good second or two before i pulled it off.

so, i swapped the stock alt back in, going to send the iraggi back in to have dominick fix it for me. now, although i have no charging warning light on (and it does work, the battery light comes on when i put the key to ignition but goes off when i start it) it doesnt seem to be charging at all.

i couldn't find much information about it on my service manual cd-rom, but my haynes manual tells me that on the harness that plugs into the alternators regulator, one of the 2 wires should be showing 12v while in ign. position, engine off, and the other should be showing 1v, going to 12v on both with the engine running. i'm showing 12v at both. i did test this with the harness unplugged from the regulator, but i dont see how that would make any difference.

i checked all fuses inside and out, and they're all good. aside from not charging, everything else seems to be working as it should. all connections are tight and the serpentine belt is not slipping. does anyone have any idea what this could be? remember, it was the other alternator i sparked on, not this one.

 

[BrooklynBay]

So you have a dual alternator set up? Do you have them in parallel or are they running different accessories? Did you check the alternator fuse? Do you have a wiring schematic of your set up?

 

[1meanGTA]

oh no, i should have worded that better, just one alt in the stock location. what i meant was i own 2 alts, the 240a is the one i shorted the battery to, i put the stock one back in, and it won't charge now.

 

[budwich]

my "take" on the charge circuit is that the two wires going to the alternator are both "hot" regardless of the key position. One is for the "field" and the other is for the "juice" (output).... this is because they are both "connected" back to the battery, in one form or the other, thru the starter. OF course, there are fuse links and fuses along each path..... but ultimately you should see 12v on both. My guess is that you have blown the breaker in the PDB.

 

[1meanGTA]

the power distribution box? thats the fusebox right? i didnt think there were any breakers, though it was all fuses, and i already checked all those, including the big 175a one that the alternator wire comes into?

 

[410Fortune]

does the starter crank?
does the fuel pump prime?
before you take the truck anywhere bench test the stock alternator you have

check the diodes in your distribution box

I believe if you are not seeing 12V at the two wires for the voltage regulator, the next step is to remove and inspect the alternator wiring, the harness that goes to the alternator is not that long or too difficult to remove and strip down...I would start there...

 

[Burns]

Link to the other thread on same topic:

http://www.explorerforum.com/forums/showthread.php?t=197329&page=2

 

[1meanGTA]

oh yeah aside from not charging, it starts and runs just fine, it's drivable. no warning lights or anything. the charging warning indicator is functional. i do see 12v at both wires going into the regulator.

diodes in the distribution box? i thought it was all fuses and relays?

 

[410Fortune]

there are two brown diodes in the PDB
I do not know of any circuit breakers, but then my knowledge is mostly of the 95-97 model explorer's, 98 have a slightly different fust box I believe....

 

[410Fortune]

What voltage do you get from the main + wire on the alternator at idle? 14V?
I have had an issue similar to yours, I was getting 14.3V at the battery and alternator when the engine running, but my battery would only hold 11.5V at all times...
It was a bad Optima red top with a dead cell...I have had this problem with the Optima red top more than once.

is it possible your new battery is faulty?

 

[jonafer]

If it ate some of the alt casing then my guess is it got hot! Then some where down your wiring harness the wires also got hot and melted the coating off. Now they are touching together and giving you a short. Strip the wire harness and take a look, It might have even burned the wires into. Good luck.

 

[1meanGTA]

there was only a spot for one diode in my pdb, and it tested ok.

 

[410Fortune]

great advice, on my BII with 290K Miles I am on my 5th alternator harness, the harness from the trucks charging wires to the alternator...its not too difficult to rebuild

 

[1meanGTA]

it isnt the battery, i already tried swapping my big yellowtop up front and its the same thing. it sits at about 11.3 with the vehicle off, 10.8 with it running, so it isnt charging much if any.

it wasnt the stock wiring that touched the casing of the alternator, it was the 1/0 gauge unfused wire directly from the battery to the alternator that touched, and it didnt melt. i'm showing good continuity from the stock wiring on the alternator positive terminal up to the fusebox, all the way to the battery. i can't see anything wrong, anywhere.

also, i put my clampmeter onto the nut on top of the alternators positive terminal and it showed 40a at idle and also at 3k rpm. however, i'm not entirely sure i was using it correctly, as thats the first time i've used it, but it was set to dc amperage, and its a cheap craftsman job.

 

[410Fortune]

Sounds like your alternator is bad OR the wiring to the voltage regulator

bench test alternator

 

[budwich]

not clear on your "12v on both".... is that with the engine off??? anther dumb question... what was the "unfused" wire going from the battery to the atternator for????

 

[410Fortune]

my guess is he has alot of stereo equipment, since he has a 240A alternator, a yellow top optima and additional charging wires over the factory harness

 

[1meanGTA]

yes i'm running about 3200 watts rms so i need a lot of charging power. have 1/0 gauge alternator and battery grounds, and the run from the alternator charging post to the battery positive. and i have 2 yellow tops

i just took the stock alt up to advance auto, it tested 130 amps, 11 volts. what the hell? it was just fine until i shorted that wire on the OTHER alternator then put it back in. is there any type of wiring issue that could kill and alt like that, because i dont really want to put my 240a one back in there and have the same thing happen.

i was showing 12v on both harness wires with it unplugged, key in ignition position, engine off.

 

[budwich]

I think that you are your own "worst enemy"... .... probably the reason for the "non-stock" alternator... heh!!!! When you say it was "fine" before shorting the other unit out.... when was the last time it was used (the old unit) and what was your "service mode" at that time.... bet you might have been running a bit "hot" before going to "non-stock"...

 

[1meanGTA]

when i say it was "fine" before shorting out the other alternator, i mean that it was fine. as in 5 minutes before i put in the 240a alt, it worked just fine, charged to 14.4. this is my daily driver and it had never shown any problems whatsoever until after i shorted that wire on the 240a.

and the only amplifier i had installed while the stock alt was in was my 300x2 amp that runs my components, i never ran the big sub amp with that alt in. there was no voltage drop at all.

so i took the 240a alt in to have it bench checked... same thing, only charges to 11v. disregard the 130a comment, i read the thing wrong, there was no amperage gauge for alternator testing.

so all my wiring seems intact... everything seems fine... except after i shorted a non fused wire from the battery to one alt, then installed another (i never tried to start the vehicle with the 240a installed after the short) and now both will only charge to 11v. this is very confusing. i sent the 240a back into dominick iraggi, so he should be able to tell me exactly why its only charging to 11v here in a few days. may shed some light on what caused it.