Battery dies overnight in cold weather

[Sirlothar]

I have a 2025 Ram 1500 Limited with the 3.0 Hurricane H/O. It has ~5k miles on it and I bought it new last October. The battery has died twice now - first time was a few weeks ago, woke up to go to work and the truck wouldn't start. I had a battery pack, tried that and it drained the pack completely within seconds. I put a voltmeter on the battery to check the voltage and it read 0.0V (never seen that before). I tried jumping it with my car, and got it to click (not turn over) a few times and the lights came on briefly, but then it died again. Ended up calling a tow truck through the dealership, and they sent a guy in a minivan to try to jump it first (since it was a battery issue). He had no luck either. Called a tow truck through insurance to take it to the dealer; the tow truck driver had a massive battery pack and tried that, and the truck started right up and kept running. I still opted to tow it to the dealer to have it checked out. They ran "diagnostics" on the battery for several hours (they had the truck for 2 days) and the battery passed the checks and held a charge, meaning they could not find a parasitic draw.

That was about 2-3 weeks ago. (for context, I live in San Antonio, TX where it is typically warm even in winter) This morning I went to start the truck and it had the same issue as before. I tried the same things (battery pack, jumping with the car) and still no luck. Also put the voltmeter on the battery after leaving it connected to the car (via jumpers) for about 20-25 min and it read 0.1V.

I don't want to have it towed to the dealer and they keep it for another few days just to tell me there is nothing wrong with the battery. Anyone else having these issues, or know what is happening? I think it may have something to do with the cold weather, but don't know why it only happens then. I saw another post that mentioned the seat warmer staying on after the truck is turned off, but I can't confirm that.

 

[FastBlackRam]

That is a serious drain to bring it down to 0.1 or 0.0 volts overnight. Something is intermittently not shutting down normally. Congrats to the dealer for figuring out your battery isn't the issue. Now they need to find the real issue. Good luck and I hope they can figure it out. Although if it only happened once in 2-3 weeks that is a real bugger to figure out.

 

[Biga]

Make sure you keep you keyfobs at least 20' away from your truck when parked. If not the key fob may keep continuing to communicate with the truck draining the battery therefore having less cold starting power.