Dead battery after camping

[Mallonjones]

I have a 2019 Forester, while on a three stay camping trip I used the backend of my car to store food and things from critters. The hatch was open quite a bit but I did make sure the cabin lights were out. After we packed up to head home I found that my battery was DEAD, this battery is only 3 months old. Luckily I was in a campground with other people so I was able to get a jump. What is the solution?
The guy at the dealer said that using it like that will always make it die, he said the hatch pulls a lot of power and could kill the battery in as little as 15 minutes, what??? Is this not an outdoor/camping vehicle. I wanted to get one of those hatch tents but don’t want to constantly be worried about my battery. What’s the “fix”? Where is the shutoff?

 

[Ecmbuster]

And the mystery Forester is?
And the mystery rear gate is a powered lift gate?

 

[Mallonjones]

And the mystery Forester is?
And the mystery rear gate is a powered lift gate?

 

[Mallonjones]

Well, now I feel stupid but I can’t find anything that says it is anything other than just a Foretser, but it does have x mode for snow and deep snow. I’m new to Subaru so I don’t know where all the secrets hide. And yes a powered lift gate that will obviously drain your battery while you’re sitting in the back looking at the ocean.

 

[Ecmbuster]

Three possible temporary solutions with the ignition key removed. If it's a proximity key, use a Faraday Cage.

Amazon.ca

1) Remove fuse SBF 5
2) Install ON / OFF switch at the LIN (Local Inter Connect Network) wire using schematic to power rear gate.
3) Use combinations 1 and 2

OR close the latch at the power rear gate.

Caution: Removing the fuse and or opening the LIN circuit may create errors within the network. The BIU is always trying to communicate with the LIN controllers

Test: An AMP clamp on the battery negative cable will allow a test to see if the networks entered sleep mode.
The magic number is about 0.030 mA

https://www.amazon.ca/UT210D-Digital-Current-Resistance-Capacitance/dp/B0753FY711