Battery/Charging issue - 1978 L6 300 4wd

[bowhunter]

So im having some mega issues with my battery not being charged by the alternator.

Have replaced the following parts:
Alternator
battery
starter silinoid
Voltage Regulator
Starter.

I checked the fuse panle and no fueses are blown.

Problem is, my battery isnt being recharged, a full charge lasts 2-3 days tops. I was out fumbling around and making sure the wires are all ran right and they appear to be, brand spankin new alternator on it, and it dies when i disconnect the negitive cable from the terminal. Im absolutely clueless on that to look at next? anyone have a wiring diagram? Or places they can point me to look/do. its a 78 f150 with the l6 and standard trans, 4x4.


Thanks guys! this is my dd sadly.

 

[DNFXDLI]

Make sure all your connections are good...no oxidation on the terminals and also check the lugs where the battery cables go into them.
Even though you have new items, have you had the alternator and battery checked?..it's possible that even new items can be bad....regulator included.

 

[5.0Flareside]

DO NOT DISCONNECT BATTERY CABLES WHILE RUNNING!!!!

sorry.. just one of them things i've always learned not to do....

secondly its very possible to get a bad Alternator.

 

[Derfus]

I've always checked the alt by pulling the battery cables while it was running. If the motor died it was a sign that the alt could be bad. It could be the wrong thing to do but it's always worked for me...

 

[bowhunter]

Had the new alt tested and all is good... still clueless! Yes, i know not to do the whole taking battery cable off but it was just out of desperation to figure out whats going on!

 

[nobodyspecial]

DO NOT DISCONNECT BATTERY CABLES WHILE RUNNING!!!!

As far as I know, this can be an issue on newer vehicles and on older vehicles it is not a problem.

From what I understand most of the sensitive electronics that run at lower voltages already use regulators that lower the voltage to the needed levels. The issue (as I understand it) is that with the battery disconnected, it places a larger strain on the regulators.

Please, somebody correct me if I am wrong, this is just how I have understood it, not that I am claiming this as truth.

 

[m78]

Are you sure that it's the battery not taking a charge ? Could it be something draining the battery when the truck is not in use.

I had a rebuilt alternator ( right out of the box ) that had a short to ground and would take 3 days to drain the battery.

 

[DNFXDLI]

As far as I know, this can be an issue on newer vehicles and on older vehicles it is not a problem.

From what I understand most of the sensitive electronics that run at lower voltages already use regulators that lower the voltage to the needed levels. The issue (as I understand it) is that with the battery disconnected, it places a larger strain on the regulators.

Please, somebody correct me if I am wrong, this is just how I have understood it, not that I am claiming this as truth.

That is how I understood it on older vehicles....it might produce a few spikes, but I have done it many times...whether it is right or wrong...and the alternator will not produce 120V with the batt. terminals disconnected.

 

[Evan's f250]

I had this same problem when i got my truck, had new battery,new alt, new regualator and it still wouldnt charge. I found out that it was the Brown wire "ignition wire" to goes to the starter solenoid from the regulator wasnt connected. You may very well have the same problem.

 

[Mil1ion]

The removing the battery cable Trick goes back to the days of GENERATORS.
They did it to EXCITE the generator so it could start producing electricity

Once alternators showed up mechanics were told to not do that anymore.

One can ruin a brand new alternator by doing this.

I'll post a diagram but My thought is you have a bad battery that is shorting out inside the case.

You can do a power drain check with the engine off and removing the positive cable shown in this site.
Just follow the directions

http://www.inliners.org/tech/tech6.html

 

[Mil1ion]

http://www.familycar.com/Classroom/charging.htm

 

[bowhunter]

Well found a short, its isolated to the rear end at the connector for the rear lights, disconnected that and the short stopped. Still cant figure out what the hell it is, and also the alternator still isnt recharging, went through two today and neither of em worked.

 

[Evan's f250]

Well found a short, its isolated to the rear end at the connector for the rear lights, disconnected that and the short stopped. Still cant figure out what the hell it is, and also the alternator still isnt recharging, went through two today and neither of em worked.

did u look to see if that brown ignition wire was hooked up to the solenoid? an alternator on these trucks will no charge without that wire. its brown and labled "I" for ignition.

 

[Fellro]

With an external regulator, wiring plays a very big part. The connection at the regulator is a common issue, and you have to be sure the alternator is even being turned on. There is a 12V source to the alternator from the ignition switch. Also, it is entirely possible for the alternator to change, but not be able to get the current to the battery due to the cable from the alternator not connecting properly.

On the disconnecting battery cable to test, I got chewed out by my alternator rebuilder for doing that, and the test vehicle was a 67 Chevelle. He explained that it could overload the diodes, blow them out, and require replacement.

 

[Mil1ion]

Diodes failure..that correct...with the engine running the current the alt is making has to go somewhere. Some people seem to ignore that fact.