Random Dead Batteries

[gabegoforth]

I have a 1996 F350 that can sit for 2 months go out and fires right up in 20 degree weather without needing to be plugged in. Then 2 days later i need to move it to do something and the batteries are so dead that the dome light wont even come on. It's got a Ts chip, glow shift gauges, and a aftermarket radio. I thought it was the radio when it did it 4 months back because I took the face plate off. It hasn't done it before then and not till this last week. It does have the factory security system that is supposed to Kill all electrical load after 40mins. The radio and gauges are the only things that I can think of that have a constant on. Its driving me crazy because there brand new batteries and Alternator.

If anyone could steer me in the right direction of things that can randomly run your battery dead that would be helpful.

[Haulstroker]

Have you tried pulling the cables and using your ammeter to see what, if any draw is there with all of the doors closed, key off, lights off, etc?

[BIG Laing]

Mine was the dome light staying on after shutting the door, and the glovebox light switch becoming loose. Just my $.02

[gabegoforth]

I cant seem to find it because its random, and it's a big draw. Not a whole lot of things can run it flat dead over night. Thats 200amp hours approximately. Dead in 24 hours. Thats about 8amps. Way more than my lights. Plus I have the factory security system that shuts everything down after 40mins. I have left the doors open before, and the lights turned of after a while.

[Haulstroker]

Apparently it's something that the system shutdown doesn't have control of. Which circuits are those? Glow plug relay getting stuck? Fuel pump? Obviously a high draw taking down those big batteries.

[gabegoforth]

Originally Posted by Haulstroker

Apparently it's something that the system shutdown doesn't have control of. Which circuits are those? Glow plug relay getting stuck? Fuel pump? Obviously a high draw taking down those big batteries.

It doesn't have a electronic fuel pump. The only thing I can think of is ether my ignition (which needs rebuilt) Or my Radio. Maybe Ill order a radio and take it to my locksmith, of course it always could be my factory security system. How many amps would it draw if for some reason the ignition were turned to the ACC position. Because I don't see any lights at night. Of course I didn't look that hard ether. What about a Brake controller. I completely forgot about that thing. I know that the trailer backup fuse is MELTED down. Never have seen that happen. I also know that there is a 30amp fuse for trailer batteries. Maybe ice getting in the 7 plug RV connector? I always wash my truck when I come home, could have sprayed some water on it.

[Haulstroker]

My brake controller went stupid, seemingly overnight. Ended up working similar to flashers, blinking on the brake lights, etc. Took a couple of days but it did drain the batteries. What makes you believe the ignition needs to be rebuilt? Do you have the stock radio or aftermarket plus big amps to drive speakers? Those amps really can suck some juice, especially the bigger ones.

[gabegoforth]

Aftermarket radio, no amps or big subs. I can use any ford key in my ignition, and pull it out in any position.