Dehumidifer System for A Trunk Gun – Part 2


In Part 1 of my last article, I delved into the specifics of which products I used to put together my dehumidifier system, so I could safely store a gun in the trunk without it rusting over time. I chose two passive units that work to draw in moisture, and can be recharged when plugged into an electrical outlet. I also included an active dehumidifier, which only ran when the car was running, but aggressively worked to lower the level of humidity in the trunk. This article will cover the tests I performed to see how well the unit did at keeping the humidity level below 50%, which is when rust begins to form.

In order to conduct the tests, I purchased an inexpensive hygrometer from Amazon. In order to get an idea of what the humidity level was typically like in the trunk, I installed it and took two separate measurements at the same time of day, two days in a row.

Day 1 – Humidity Reading (No System)
Outside humidity: 64%
Outside temperature: 33 degrees

Day 2 – Humidity Reading (No System)
Outside humidity: 82%
Outside temperature: 25 degrees

One thing I noticed is the humidity tends to greatly increase as the outside temperature becomes colder. I then installed the system and let it sit overnight without running the car. My average driving time on a typical day is roughly one hour. I made sure the system was plugged in and running as soon as the car started, so I could see the full extent of the system. While being completely expose to the outside elements, I took another reading at roughly the same time in the afternoon as the two previous readings. I was pleased to see the system was keeping the trunk humidity very low.

Full System Test
Outside humidity: 74%
Outside temperature: 15 degrees

As you can see from the reading on the hygrometer, the dehumidifier system is working flawlessly at keeping humidity to a safe level. The silica gel beads in the passive moisture collectors seem to be recharging fast enough to keep them fresh as well. If you really wanted to push the humidity level down further, you can always add an additional active dehumidifier, or a couple more passive units. I’ll be keeping this system as-is for now, since it leaves me enough trunk space for my guns, gear and bug out bag. If you like the system, have questions, etc., feel free to leave a comment below!


The author

Tyler Capobres has years of experience torture testing guns, knives and gear to their limit. If he's not writing about gun projects, reviewing products or mocking anti-gun zealots on Twitter, you'll find him at the range. Owner of, a website dedicated to all gun and knife enthusiasts. Author of "Punching Holes", a book showing how anyone can save 15-40% on guns, ammo, knives and more, by purchasing them at wholesale prices.

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