My truck sets a day or two and will barely start or will not start , batteries are Interstate one year old , tested ok both of them .Did the test light to positive terminal trick where you can see what is drawing , my courtesy light group and computer fuse when pulled test light goes out . I cant see how this would be that big of a draw on the batteries unless there is something going on with one of those circuits causing a larger than normal draw . Any ideas ? Has anyone had anything similar happen like this ?

 

Have you added anything, like a stereo amplifier or other electronic hardware?

 

no add ons . This is wearing me out !! Can't put my finger on it .

 

Is the alternator warm after it has sat for a few hrs?

 

Alternator output?

 

I have the same issue on my 2003 F350. It was doing this completely stock when I got it and was having this problem for several months. I also have Interstate batteries that I had tested as well as the alternator being tested. All tested good. I am thinking of changing the batteries.

 

In the "for what's its worth department, what I have found if I simply sit until my volt meter says the glow plug is shut off, it starts right up. If I try to start before the voltage jumps back up, much harder to start. Go figure.

Steve

 

going to check altenator

 

When you do check your alternator, pull the alternator plug and check the volage of the wire leads. You should have 12v on one and 0 on the other with the key off. If you have voltage on both, then you have found your drain.

I have a 2000 F-350 with dual altenators and currently have this same electrical drain. I posted this problme last week but no one on this forum has replied. Perhaps you will have better luck.

 

Having recently gone through this and finally have it solved, I again throw my two cents out here.

Having just replaced batteries that were barely off warranty, I was having a slow start or no start if I let my truck sit more than 3, maybe four days. This went on for quite a while and I really did a lot of meter work, which I am pretty reasonable with and I could not nail it down. It should have been obvious to me and in hindsight is, but with minimal draws, I had nothing that could crush my batteries to the degree I was finding.

Anyway, I have a high-end charger that can equalize so I charged them up and load tested them and one tested really good and one tested good, but barely. So it went on and on, so I disconnected them and charged them individually and let em sit. In the morning my good battery was still at 12.66 volts where they both had started out, but the remaining battery was at 10.75 (again connected to nothing so no draw of any kind). Finally I measured specific gravity, which I virtually never do and found I had one cell completely gone, wouldn't even register on the tester.

Finally, I hooked up the good battery, left the bad battery unhooked and my engine cranked and fired instantly, much faster than previously. May well not be your problem, but what I had was a battery that was beginning to fail with a bad cell, but it did not show up immediately on testing.

Just a thought,

Steve

 

Did you ever check your alternator? If so, what did you find?

 

I have a drawl on my system I had it checked because of the same problem 3-4 days and it didn't want to start, not bad until it starts getting colder out. My GEM module isn't shutting off and draining my batterys. I also have interstate batterys.

 

Same here. To broke to go to a dealership the find what on the gem circuit is actually draining the batteries. Its frustrating to no end thats for sure.

 

also feel the alternator when the engine is cold. if it is warm, it is shot. just because the part store idiots test it as good, it don''t mean it is good. they only test for voltage output. if the diodes go bad it will drain the batteries, and be warm to to hand when the engine is cold.