So tonight my truck died. Wouldn't start, wouldn't even turn over. Dome/door lights were really dim and flickering. Windows wouldn't roll up, power locks were dead, etc... There was no warning, it worked fine 15 minutes before that. I pulled the battery and had it tested, and he said I needed a new one. Once i got it in, I drove it to the parts store, and had them do an alternator test, and everything showed good.
How reliable are these tests? What are the odds that it could be my alternator? Is there any way to check the battery's charge? It seems the boost gauge replaced the battery meter in our trucks.

 

The odds are that it was your battery. You can check your alternator while your engine is running by measuring across your batt terminals. You should read around 13.4 volts.

 

the ford battery meter does nothing until the battery is dead..LOL

buy a multi meter at your favorite store for 10 to 20 bucks.....

test battery with truck off....should be 12.6 volts

test with truck running should be 13.4 to 14 volts...

 

Mine did almost the exact same thing...truck was fine, parked it, went out 15 minutes later to go someplace and nothing,stone dead. I checked the battery
with a voltmeter and it read about 12.5 volts, turned the key "on" and it dropped to like 3 volts...put in a new battery and it's been great ever since.
When it's running, the meter shows about 14.25 volts. The OE Motorcrap battery shorted out with no warning whatsoever.

 

So after I got the alternator tested the 1st time, I went to another part store on my way to work, and THIS guy told me that my battery wasn't charging. 2 people told me 2 different things. So I took it to the dealer, since I'm due for my 60K service anyway. It turns out that the alternator is fine.

 

Had the same thing on the wife's. No warning at all. Parked it, came back 30 min later and stone dead.

 

Same thing happened to me, turned out the main positive cable was corroded a bit in the Stinger ring terminal. Cleaned up all my connections and voila, problem solved.

,Marc

 

On my 00 L, the best way to test an alternator is to get the truck started and REMOVE the negative terminal connector. If the Truck SHUTS OFF the alternator is gone. If it keeps running, its the battery.

 

I've heard that when you do that it will burn out your alternator, and that only works on generators.

 

It works. Just don't have every electrical device turned on when you try it though. If its your battery, the engine will not turn off. Just don't drive around town without your battery.
An alternator is a generator. Its generating electricity from the rotating shaft.

 

That is a VERY bad idea on a computer controlled vehicle......you can easily fry the ECU doing that......it is also fairly dangerous with the high current being put out by the alternator.

 

X2. Old non-comp cars yes, anything with any type of computer, heck no.

An alternator is NOT a generator. A generator produces DC voltage, and not very well at that. An alternator produces Alternating Current, hence the name, that is rectified to DC, typically with diodes.
Us old farts grew up with cars that had 35-50 amp alternators on them. Todays 100-165 amp units can destroy an electrical system in a split second if played with like that (pulling the battery terminal and reconnecting). Keep in mind that the computer was never designed to see current rise and drop that quickly.

SL

 

I didn't post this!!?? "An alternator is a generator. Its generating electricity from the rotating shaft." That was Rocketir