Folks,

First let me thank anyone who responds. I have no clue when it comes to engines, especially electrical issues. I have a 2000 F150 5.4L V8 which doesn't want to hold a charge on the battery. I can jump it and it starts just fine, but even after running it a while attempts to restart end up requiring a jump. I'm thinking it may be the alternator, but again, I have no real clue when it comes to this stuff. I'd rather not take it to a dealer and pay ridiculous prices. I've had the battery replaced twice now (once thinking it was the battery, and the second time the shop traced out the electrical system and didn't find anyting shorting so they thought a bad battery), but it doesn't seem to make a difference. Thanks again...

 

I would take the alternator off and have it tested at AutoZone. If you can't remove the alternator from the truck it can be tested on the truck but I think its more accurate off the truck.

 

Go to Sears or Radio Shack and buy a multimeter (with batteries) for $20.

Take it home and measure your battery voltage before and after starting.

Let us know what you read.

Steve

 

I used a Fluke meter and checked the VDC. Prior to jumping and starting, I was ready 9.04 VDC (which consistently dropped until i stopped reading at about 8.49 VDC). Once I started it, it was readying right abour 14.0 VDC.

 

if all your electrical stuff work as long as the truck is running then there is no way it's the alternator...

it's more than likely the battery. get the battery tested at Advanced Auto / Auto Zone / O Rielly's etc

 

The battery has been replace two seperate times already. Once when the problem first started, and once after tests were run to see if there was a short causing a drain on the battery. The problem is still happening, no charge being held and at this point I have to jump the truck every time I want to drive it.

 

If you had those readings in the first place, why didn't you give them then?

Well, I had that same problem buying batteries at WalMart... The yellow ones were only lasting 6 months, tops....

The local store got tired of replacing them, so I guess they finally decided to give me a good one.

Perform a current draw test to see how much is being pulled after the battery saver relay kicks out.

Steve

 

I didn't have them in the first place, just ran them when you put up your posting. I'll touch base back with where I purchased the battery also.

Is there a posting on how to perform a current draw test? I'm not overly familiar with this stuff.

I do appreciate ALL of the helpful information. If I've come across differently, my apologies.

 

Switch your Fluke test leads to check amperage then disconnect your + wire from your battery and connect the test leads of the Fluke in series with the + wire (one lead on the + battery post and the other on the wire). DO NOT TRY TO CRANK THE ENGINE WITH THE FLUKE CONNECTED if you do you will blow the internal fuse. If you electrical system is good you should see very little load (maybe .5 amps) If you get more than .5 amps isolate the load by pulling fuses 1 at a time until the load drops.

 

To fine-tune what LastSplash said:

Use the NEGATIVE battery lead, not the positive. It's safer and will yield the same results. If you're using a digital meter, the meter leat polarity doesn't matter, just ignore the polarity indicated on the meter.

Start with the meter on it's highest range setting unless it is an auto-ranging meter. Swith to lower ranges until you read the max resolution.

Make certain the doors are closed and all lights are off. Do not open thedoors or intentionally switch the lights on while the meter is in circuit. otherwise, you run the risk of either damaging the meter or, at a minimum, blowing the internal fuse.

For the first 30 minutes or so, you should see up to around 200-300 mA current draw. At that point, the battery saver relay should kick out automatically and the current draw should drop to 50 mA or less.

Common problems include the underhood and glovebox lamps not shutting off.

Steve

 

I have a 2000 F-150 5.4 also, I have to drive it every day or else it will go dead on me. I have checked everything on my truck nothing that i can find can stop this. So i try to go somewhere at least once a day in it. Still hard to do with gas prices i know.



Just a thought do you have any aftermarket items on your truck such as a Amp? Aftermarket radio? Extra Lights?, Fog Lights? those may be good places to start.

Good luck.

 

I appreciate all the advice. I won't have time tonight, but will try it out tomorrow and let you all know. I really appreciate all the assistance!!

 

I am hoping for some help, I have a 2000 f150, always ran great. About a month ago, i noticed my battery light on while driving, its kinda new, but checked it anyways, it tested good, windows wouldnt roll down or anything, charged battery that night, it started fine next morning. About a week later, same thing except i shut it off at the gas station, had to jump it, next day same thing, but had to tap the starter. So i replaced the starter, altenator, and the battery, same thing, battery light on, after charging the battery, it starts, but light still on, and drains battery, like its the altenator again, and have replaced some fuses, the mini ones, any sugesstions? Can this altenator be bad or am i overlooking something? I am in no way a master mechanic, just barely can figure some stuff out, raise my grandkids tho and cannot afford high prices to fix it, please help if you might know whats wrong, thanks in advance.

 

David, first welcome to the site. There are a ton of guys here that can give you a hand, unfortunately I'm probably not one of them. BTW nice job using the search for your problem. The only trouble is those threads are best used for reference because they are so old (like me).

I'll take a stab at it for you though. Do you have voltage to the alt with the key in the run position? You need to so the alt can make power. There is (I think) a 10a fuse that controls this. Also there are 2 fuse boxes, 1 in the cab and 1 under the hood, check them both because I'm not sure where the charge fuse is located. Also when you check the fuse, use a multi meter either for power across the little buttons on the back or for continuity if the fuse is in your hand.

There are some sharp guys here like I said earlier, but it would probably be best if you start a new thread in the electrical section so it will get noticed.

Good luck and post what the fix was so the next guy can have a fighting chance.