stock alternator only charging to 12v?

[Lil Poot 5,000+ posts]

some of you may have seen my recent thread regarding the broken terminal post on my iraggi alt. for those that didnt, while swapping my iraggi alt into my 98 explorer (5.0 v8) i broke off the battery terminal post and a hot 12v lead sparked on the alternator casing. i took the iraggi back out, swapped my stock one back in.

after i put the stock one back in, it wont even charge to 12v. i thought maybe the short had done something to my battery, so i switched the battery with my other yellow top and get the same thing. i have driven it to try and get the voltage up, it stays steady at 10.8 while idling, doesnt seem to be changing much if any while i drive it. when i turn the truck off, the battery voltage jumps back up to about 11.3, so i dont think the alt is charging at all. i have the stock alt to battery positive wiring still hooked up, but as far as i know it didnt short out, it was the 1/0 gauge wire i have there that sparked. was a pretty nasty spark, burned away some of the casing of the alternator.

aside from not charging to 14.4 like it used to, everything seems to be working fine, no warning lights or anything else. any thoughts on what i might have done to my charging system? i can't find any blown fuses.

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[IgnoreMe 5,000+ posts]

i think you might have blown the warning indicator that would initiate a sequence that would usually excite the alternator.

if your alternator doesnt get a small amount of battery current to excite and produce the magnetic field you the alternator wont charge. and that small amount of current passes through your warning indicator light (on most cars)

 

[IgnoreMe 5,000+ posts]

here is some info i found on the googlenator

Most modern vehicles have an indicator light located on the dash to alert the driver of a malfunction in the charging system. It is also used to pass a small amount of battery current to the alternator rotor to excite and produce the magnetic field until the alternator begins to charge and can assume this function itself.
Because the bulb circuit is connected to the battery and alternator sides, any movement of current between the two units will cause the bulb to light. As the alternator begins to charge and the produced voltage reaches the battery voltage, the current between the two units ceases to move and the bulb will go out. If either the battery or the alternator should fail as the vehicle is being driven, the difference of voltage between the two units will allow current to flow and the bulb to light, warning the driver of a malfunction.

An ammeter also indicates the condition of the charging system. A low battery will be indicated by a high charging current toward (+) side of the gauge. A wiring short or faulty accessory will show as a high rate of discharge toward (-) side of the gauge. It's normal for the gauge to move a slight amount in either direction.

 

[Lil Poot 5,000+ posts]

i knew about that, the charging system warning light is fine. light comes on when i switch to ignition with the engine off. i think theres a problem with the voltage going to the regulator. the regulator harness has 2 pins, one should be showing 12v at ignition with engine off and the other at 1v, with both at 12v with the engine running. i'm showing 12v at both with the engine off. i think i'm just going to take it into a ford dealership and let them **** me tomorrow, this is over my head. all of the fusible links and fuses are fine, except for that harness, as far as i can tell everything is as it should be.

 

[mlstrass 5,000+ posts]

belt could be loose/slipping...

 

[Lil Poot 5,000+ posts]

belts fine, connections all good.