I have a 1999 F150 V-6, Standard Trans. The battery will not stay charge (new battery). I have jumped started it and removed a battery cable once started and it kept running. (assume alternator is good). Could it be the battery saver relay ( brother said check it) or something else? If so, where it it?

 

Do you have a programmer, cb radio, external lights, or a sound system. the list is really endless to what it can be. i had the same problem once i went off to college again in the fall since i didnt drive it that much. ended up being my programmer.

 

You need to do more troubleshooting here. What is the voltage across the battery terminals with the engine running? If it's in the 14V range, your alternator's fine.

If the charging voltage is good, you need to measure the current draw with the engine off, and about 3 hours after engine shutdown. This is rather difficult. You have to connect an ammeter in series with the negative battery cable, without opening a door, which would start up a whole new shutdown sequence and without disconnecting the battery cable before connecting the ammeter!

One way is to disconnect the negative cable, then attach a jumper wire between it and the negative post. Go have dinner and a beer (Or a beer and dinner - your choice. Maybe have another beer too. You need to let some time pass).

Then sneak out and attach your ammeter probes (probably on a 2 Amp range, if you have it) to the cable and to the negative post of the battery. THEN, disconnect one end of the jumper wire. Now your ammeter is the "jumper and you are measuring the current draw. Anything higher than about 0.05 Amps is "above normal". A battery should last about 42 days before being discharged at that rate.

- Jack

 

I am having constant dead battery problems myself. I know I dont drive it enough. Maybe once a week or so but I wouldnt think the battery would go totally dead in that time. I was just curious since you said it was your programmer. Do they draw power while just sitting? I have had my battery tested and it came up fine. I also have no other aftermarket electronics on my truck. The place that tested my battery said to maybe have the alternator tested but I havent done that yet. It makes no noise and havent had any battery lights come on. Thoughts?

Thanks
Sean

 

Yes the programmer will draw double the amp draw on the battery that the truck uses.

Jack did a nice write up on the calculations in this thread.
https://www.f150online.com/forums/4526706-post6.html

Question on the battery test, what test was done ?

I have seen posts that Autozone uses a little hand held tester, and call it a load test in the parking lot in 5 min, but this is not a load test, just a slight better than meter testing the battery ( and you can do better at home testing the battery yourself with a meter and battery charger ).

 

IF you have a programmer like the Edge/Gryphon plugged in, it will draw 0.05 Amps for its "keep alive" memory. My truck pulls an additional 0.05 Amps at rest for all of its OEM electronics. Aftermarket things like headunits, etc. may well up that current draw. If there is a constant 0.1 Amp drain (what I have) your battery will be dead in slightly over 20 days. Opening a door will greatly increase the current draw for a while. A Battery Maintainer will prevent discharge without boiling the battery and that's what I use.

- Jack

 

Thanks for the replies guys! I do leave my Gryphon plugged in all the time but I will leave it unplugged and see what happens. MIne hasnt been making it close to 20 days. Its pretty weak after about 5 days and completely dead in 7 days. I dont know what else could be drawing other than the Gryphon since it usually sits in the garage untouched when not driven.

As for the test they did, it was a handheld Interstate Batteries tester at Firestone. I would think it would be a good machine but who knows. I dont have a meter so I'm kinda screwed there. I may look into a maintainer.

Thanks
Sean