GEN 1 Battery Keeps Dying. Input needed

Hey guys, I have an electrical gremlin in my truck.

Just for context, 13 screw, 30k. A few electrical mods. Lights, winch. Recently installed Odyssey battery. Everything is wired up to factory up-fitters except winch but it has a separate control switch that is off.

I have an intermittent issue where when the truck sits for a few days, I go to start it and it is dead. So dead that the remote wont unlock the door, no lights on dash. This happened once before when I switched the original battery with an Odyssey. I was able to get a new battery because I thought maybe it was a bad battery. But it just happened again.

Any idea on what this could be? Nothing is on in the truck, HL are in off mode, radio off, HVAC off and dome lights aren't staying on. Plus this is very intermittent. I travel frequently so truck sits and most times is fine, so its not every time the truck sits.

Truck is out of warranty of course, and I dont really want to take it to the dealer without some idea of what this could be.

I really appreciate any insight into this.

if you have a backup camera it is possible that it is shorting out. that camera draws about 5 amps and will drain your battery, corrosion will sometimes lead to a short. check the connections and the harness

The way I handle this situation is. hook up a digital multimeter at the negative post in series. set the meter to milliamps and use the 10amp setting, my meter can record the minimum and maximum readings, I leave it on for awhile and monitor the readings. when it spikes and draws a lot of milliamps usually over maybe 500 you can go fuse by fuse and disconnect till the draw goes down. when you connect this way the first time you will get a spike in the reading, this is normal, once the computers go in rest mode it should settle down to about 90 or so milliamps. maybe lower. but using the owners manual make sure you know what fuses you are pulling and what components they run. this works for me.

@marilynsride I will check the rear camera harness. I do live in the NW so it has seen plenty of water.
@beemerman, thanks for the troubleshooting tip.

I was reading that there is some sort of battery low voltage protection system. Obviously, that isnt working. Wonder if that is faulty?

The pcm (powertrain control module) can detect low voltage, I don't know if it can shut down a battery draw. I would have the truck scanned for codes. its possible you have a alternator diode bad, that can kill a battery. or the scan can lead you to a component that has a voltage draw.