Dont know which it is. There are no dash guages, no speedometer, Tach WOrks, and anything I turn on (blower, radio etc) causes the engine to nearly die.

Whaddaya think?
How do I know?

 

Would seem to be the alternator at first glance. A meter should read between 13 to 14 volts if the alt is working, 11 to 12 if not. But with the guages acting up it makes me think you have a bad cell in your battery (cell shorting out ). Try disconnecting the battery after you start it.

 

what ever you do, dont disconnect the battery when running. the alternator will put out 40 volts and blow the comuter and all electronics out. put a charger on the battery and charge it up all day. start the truck and see how it does. a full battery will run several hours without a working alternator. if the battery goes dead while cranking or shortly therafter, then the battery is bad.

 

Thanks guys, and thanks for responding so quickly.
I have charged the battery for three hours off another car.
I have the alternator out now, so I'll have to wait to test.
AZ tested the ALt and it fialed.
A new alt from AZ, 1yr guarentee is $100.21
Didn't check at ford.
All of a sudden a cup of coffee represents a Money problem when I spent all I had on an Alternator.

 

What? Some cars won't run with out a battery but disconnecting a battery while running has zero effect on the electronics, and if your alt puts out 40 volts at any point, then you may want to go to advance yourself.

btw, if it dose turn out to be the alt, spend a few extra bucks to get the one with the lifetime warrenty, with those aftermarket parts you'll probably need it.

 

Matt, you think the FoMoCo parts are better?
Ford parts are closed up from Sat AM to Mon AM.
I got a few minutes, I'll call them and see.

When I retired and went on the road with the Ford Diesel and the 5er, we started buying the lifetime stuff from NAPA. There's quite a lot of the NAPA stores around and they keep about the same hours as Ford.

NAPA parts only need a one year guarentee though because you'll be back within a year.

Soon we found out NAPA wasn't always open when we needed them, and sometimes the nearest NAPA store was a Fur piece away.

So we started buying from AZ. They are in almost every city and open every day.

Me the retired guy usually buys the Lifetime guarentee.

Gotta go...

 

Yes, as are AC Delco and Mopar. I just like the lifetime warrenty on atl's and starters because there easy swaps, so I don't mind going for the cheaper aftermarket part. Any real battery shop ( that rebuilds alternators and such) will tell you that the oem stuff is far and away better than almost any aftermarket stuff when it comes to alt's and starters..

 

Thanks Matt.
It was the ALT. Ford was closed.
So I went on down the road and I got the Lifetime from AZ.
Wasnt real easy to install, but with the help of a neighbor we got that serpentine belt on and away it went. $136 bucks later...

 

The battery is used for starting and running accessories while the engine is off. Once started, everything runs off of the alternator. The battery is recharged and acts as a capacitor to soak up any voltage spike. Yes an alternator can spike high voltage when you unhook the battery while running. In the old days it didn't matter as much, but with all of the electronics on these newer vehicles, it can easily fry them and you will be out a bunch of money replacing everything.

 

I'd have to disagree. While the theory is sound, for about the last 15 years the electronic components, for one are much less vulnerable to any kind of spike, be it static or whatever, plus all the circuits are isolated to the point where you could pop (spike) the system with 100 volts DC without damage. I can remember not so long ago, when this wasn't true, that you had to turn on the blower motor when jumping a car so as not to "spike" the ECM and screw the fuel injection. Most OBD1 and all OBD2 are all but immune to DC spikes.

I know I'm opening up a can of worms here, but hey, that's about all I'm good for... right.... Plus, how many of you have a degree in electronics..hmmmm.. not that it makes me any smarter than anyone else, but you'd be suprised how hard it is to work that thing into a conversation..

 

Yes, if you have a BSEE degree, I'm real surprised at your comments!!! Obviously, either you weren't taught it, or you forgot what Di/Dt is.

NEVER disconnect a battery cable with the engine running, PERIOD!!!

 

He must have cut class that day

 

I'll be glad to respond to a resoned argument. Big fonts don't change facts. If you need me to, I'll be glad to explane what an isolated circuit is but it's been my exsperence that "ol wives tales" don't die in the face of facts.

 

Go do it, let us know if nothing happens.

 

mmmmm lets see here. An Auto is a big Series-Parallel circuit with two Power sources.
The Alt puts out a high amplitude AC signal. That has to be modulated by the Regulator which is usually in the Alt on most of the new auto's.

So...if we disconnect the Battery while the Engine is running. The Regulator sees the Battery's absense as a "LOW" signal and excites the Alt to full Charge.

The Alt goes to work, the signal goes high, but the Regulator wont let that High Amplitude signal go past the FIlter in the output section of the modulator.
(Right here I have a problem. Where does the small voltage Exciter source come from.
That's usually from the Battery. The Alt needs to make an electromagnet out of the armeture to produce the High amplitude signal?)[I]

So nothing should happen to any componants in the Charging system, or in the associated logic systems when you disconnect the Battery.

However IF you re-connect the battery something different happens. Then you might get a Surge from the Alt, depending on the Regulator circuit.
That could do some damage if the Circuits being discussed dont have some kind of an impedence filter on the incoming Voltage and Logic lines.

That's my understanding of the system.