so i was cleaning the MAF and i bumped the alternator power wire and it was loose. i went to tighten it and the nut just twisted and broke off the stud between the 2 nuts.. so theres still enough there to remove the remaining nut and just add 2 short nuts and be fine.

well the nut was welded to the stud from overheating and also blew one of those little black diodes/resistor things.. i cut the nut off the stud and fixed the connection but what about the burnt thing? not sure what it is to look for and if i can salvage from other things.. like what other alternator have them? maybe radio shack? maybe in ovens or microwaves?

i believe the issue was the thing got hot from the poor connection and that was the closest thing to it so it took the heat. it does still work a little.. when idling it read 14v but once i gas it it drops and the battery indicator lights up then when i let off its back to normal. if i disconnect the batttery it dies. it wont run on alt alone.
any suggestions? well other than but a new one

 

Alternator is not working regardless of voltage you saw at idle.

The diode could be replaced, but alternator should still work without it, and since it doesn't there are other issues
There are 6 to 9 diodes in an alternator, if 1 or 2 are removed or "broken" then alternator would still work, it would just have less AMP production available, so voltage would be low and idle and get higher with higher RPM, yours was the opposite so there are other issue internally besides the diodes

I think a used one will be least expensive option.

Parts break down is here: Alternator rebuilding. | Ford Explorer and Ford Ranger Forums - Serious Explorations

Replacement parts will total more than complete working alternator.
There are shops that rebuild alternators, starters and any electric motors really, they are often the best places to get these parts, and recommendations on whether it is worth it or not

 

@ brc0703
I took a look at your "About Me" page
If that 1200watt amp you're running is in this Ranger, you may want to consider a heavier alternator.
I'm thinking that's why this one got so hot.

 

1,200watt amp....................failed to mention that part, lol

YES!!!!

That is what melted the terminal, 100% no doubt
Good one Jeff R 1

Audio watts also don't convert to AMPs the same as other wattage does

You need amplifier efficiency rating, it is usually about 80%
Then you do 1200 / .8 = 1500 << this is the electrical wattage

Then you do the OHMs Law math
Watts / Volts = AMPs

Use 13volts since with engine running voltage should be 13.5v average after 5 minutes of driving

1500 / 13 = 115.3 AMPs

Stock Ranger electrics should draw about 60 AMPs with every thing on, including power windows going up or down
This is why stock alternator is a 90-100 AMP model
An alternators AMP rating is for when the engine is at 1,800RPMs, at idle, 800 RPM, the alternator can only generate about 2/3rd of its rating

So you will need a 170 AMP alternator, if you run stereo at full volume, 150 if you stay at 1/2 volume

EDIT:
Just looked at description and that says 1,800watt!!
1800 / .8 = 2250 watts
2250 / 13 = 173 AMPs <<<<<<holy smokes...................is what happened to the alternator


Many don't understand audio watts
2 watts is NOT twice as loud as 1 watt

To double the sound level you need 10 TIMES the watts
So 10watts will be twice as loud as 1 watt

Human ear can start to hear a rise in levels at 5 times the wattage
So at 5 watts you would notice an increase in volume

Lets move up in watts
So a 1500 watt amplifier and a 500watt amplifier would sound exactly the same to you if both were at full volume, because it is only 3 times the wattage
You would need to go to 2,500watts to hear an increase, and 5,000watts to get double the volume of 500watt amp
Audio shops, home or car, should KNOW this, it is no big secret, lol, but they tend to avoid mentioning it to get a few extra $$ in up selling customer to a 1,500watt amp from a 1,000watt amp.

This is just science, so not an opinion

I would look at dropping down the watts, you won't even notice the change, and just keep the stickers to show you have 1,800watt
You can then use a reasonable amp alternator

600watt amplifier would be 57.6amps

This is why stock vehicle audio systems are 40watts no reason to go higher because there would be no noticeable loudness increase until you got to 200watts or higher
But you do gain the lower amp draw so alternator works fine

 

i havent had the amp installed since the motor was rebuilt. have about 1500mi and i havent even turned on the radio because im listening to truck all the time.. so cant blame the amp.. i have a capacitor that goes with it and the truck does well.
now when i stapped 2 of these amps together making 3600 watts pushing a 2000 watt sub (picture below) in a box that took up almost all back seat.. now that was pulling enough power i watched the battery go down and the truck died.. so i sold the sub and 1 amp.. but that was like 3 years ago..one time i went bowling and when i got inside people said they thought there was an eathquake. lol and there is no sticker.. i try to keep it hidden and turn off blocks before i get home.. i am glad how the box turned out..(pic below) i dont work well with wood.. im more a metal guy

ok back to alternator..i already ordered a new rectifier that should be here tomorrow.. i dismantled it and took off the rectifier and saw a burnt diode and little green box where the battery wire connects had oozed out some stuff.. still need a vehicle for 2 days so took my chances and i just put it back together with the original motorcraft regulator and its working now. the guage is reading just a tad lower than it normally does. my scanner app shows voltage around 14.1 normal and 13.8 with lights on.. i get out and check it after each drive and its not been too hot or smelled burnt at all.. just need another 10 miles to take my brother to have stitches removed.
thanks for help and the link to that alt tear down page it was exactly what i looking for

the angled section in the center with the cap on it is hinged so i can still access the jack

this hit way harder with the sub installed inverted like this

 

ok so what could cause it to possibly burn again?

from the beggining..

i rebuilt with an ebay repair kit that came with the regulator, brushes w/ housing and rotor contacts. after about 1500 miles it toasted the batt wire at the alt connecting. removed and dismantled to find a fried a diode. i reassembled and it did not work. it swapped out the regulator for the original motorcraft one and it idled a little high and the gauge was a tad low but worked ok for a few days waiting for the new rectifier. i replaced the rectifier and it was back to normal for maybe 20 miles and now gauge reads a little low and the truck idle is high again.

havent pulled it yet to verify im waiting for it to cool down a bit just trying to get a game plan.

 

The capacitor only works for 2 seconds, if that, it is just to smooth Voltage nothing to do with AMPs needed.

So I would calculate how many AMPs your vehicle needs, use 50amps for stock truck electrics and add new equipment to that.

Then multiply by 1.3 to get alternator amps needed at idle
As said alternators are rated at 1,800RPMs, so 90amp alternator has 60amps at idle, 2/3s of full power

I would also Ground the alternator and increase the wire size from alternator to battery, B+ wire
Look at a 12volt wire gauge table to see what gauge Ground and Power wire to use

 

my understanding of a cap is that its like a little storage bank thats mounted closer to the amp and capable of delivering the power needed faster while taking that sudden drain off the battery and alt. i have nothing to back that up.. like i said my understanding..



i ordered a new rectifier off ebay.. just a standard 90 amp replacement and it seems to be doing ok.. been a about a week and havent needed my jumpers yet.. knock on wood... have another question about fuel trims but ill go to another thread for that.. thanks for the help

 

Capacitor is used to smooth line voltage, if you have 12volts on a power wire then the capacitor holds 12volts, if line voltage drops to 11.8volts then capacitor will discharge that .2volts for a second or two and then have 11.8volts until line voltage returns to 12volts then capacitor have 12volts again.

Think of it as a pressure tank on water system, if you add 10psi of pressure to the system the diaphragm in the pressure tank is at 10psi, if pressure drops to 8psi then pressure tank keeps it at 10psi until diaphragm loses that 2psi and pressure tank is now at 8psi, then goes back to 10psi when system pressure returns to 10psi
How long it can hold 8psi pressure at 10psi depends on the size of the tank


On subwoofer amplifiers they use capacitors for momentary drops in line voltage as sub moves alot of air, low bass note.
This gives better sound and prevents "dimming" of lights in a vehicle with marginal AMP capacity, capacitors "stored" power is nothing like a batteries "stored" power, it doesn't last long, it is used to prevent ripples in power lines.