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Any mustang guys in here? Having trouble with 07 mustang . Died battery three days ago charged old battery got started ,drove to work two days ago,ran fine,got in yesterday died ,took truck got new battery ,put it in last night ,today
Most of the Auto parts stores like Autozone & Pep Boys have charging system testers that will check the Alt on the vehicle. Good ones will detect a bad diode.
If the diode is bad it is usually easier to just replace the alternator.
Check voltage across battery terminals with key off. Needs to be at least 12.5v (12.8v is full charge) if in heated garage. Outside, very cold, I dont have an exact number, but still above 12.0.
If that is ok, recheck battery terminals. It is acting like my F-150 did when there was corrosion between the terminal and battery post.
If you jump start the car, recheck with voltmeter with car running. Needs to be at least 13.8v to charge. If its lower, then suspect alternator, diodes, brushes, internal regulator or wiring connections (check first). I would not just throw in a rebuilt alternator without having it tested first.
A bad diode won't stop the alternator from charging.
The diode acts as a one way valve and stops the battery from feeding back through the alternator when the engine is off.
Got it started by bump starting it ,got it warmed up ,turned it off started right back up.
A little history about this car .it was my sons car who was in the army .i helped with the down payment and we would shear the car while he was deployed .
Will long story short he got heart in training and never got deployed .
He started putting after market stuff on it and highly modified it !
One thing he did was put under pulleys on it . This is a big resin the battery is shot , he never put a high out put alternator in it ,he also put long tube headers on it and did not rap them with heat tape . I know I should put a high out put alternator in it , I think the starter is bad in it . I cranked on it the other day with a weak battery over and over to start it , that did not help the starter. My buddy who is a ford mechanic thinks it is bad .
I will see tomorrow if the starter works after it is cold.
Thanks for the help!
A bad diode won't stop the alternator from charging.
The diode acts as a one way valve and stops the battery from feeding back through the alternator when the engine is off.
Ive had bad diodes in a Chrysler alternator. What typically happens is you loose 1/3 of the charging current for each diode that is bad. So, a 60A unit becomes a 40A for example.
The regulator is what stops the feedback by shutting off field current. What the diodes do in a bridge circuit, by being one-way, convert alternating current (hence the name alternator) into direct current usable by a vehicle electrical system. There is no commutator like an old generator, just slip rings. The diodes electrically replace the commutator.
J&M,
I'm sure you're right on this.
I tried to use a term that was familiar and self explanatory.
The '07 Mustang has a 6G alternator.
A lot of people complain that aftermarket stereo amps kill their alternator.
Underdrive pulleys are not gaining any appreciable horsepower.
They are fine in an all out racing application because the engine is at sustained rev's beyond normal redline and you don't want to trash the alternator or water pump.
If any of my information is correct the car's PCM controls the field current with a PWM signal to an FET, and the feedback signal from the regulator to the PCM will lower the set point in order to provide a smooth 'ramp up' of load.
102-063 seems to be 7sec 'soft start'.
next time you are going to let it sit, try disconnecting the radio.
i have had 4 ford radios so far go bad and kill the battery after sitting for 3-4 days.
take the radio out and it will start rite up after sitting for 3 months. put the radio back in and the battery is dead in 4 days.
BMW did the same thing. Factory Pioneer audio system and/or alarm would drain the battery in a week if the car wasnt started. That drain, combined with a weak alternator (13.8v max output), probably similar to the underdrive pulley situation, caused a problem.