Rust is the Enemy

[whydontu]

Yup, nothing like living in a rain forest next to a 10^100000 cubic kilometer salt water puddle. Lucky easteners.

Or 150 yards from a tidal estuary that changes from fresh water to salt water twice a day. Coupled with an average of 170 days of rain per year. 52 days so far in 2025. However, no salt on our roads.

 

[Mike R]

One of our customers specified a breather valve for our electrical enclosure box, its a simple (but expensive) one way valve to let air and moisture out but prevent flow back in. The idea being that any accumulation of moisture has a way out.
Another idea, think about what they do to toilet tanks these days, lined with foam inside. Old tanks used to condense on the outside due to the temperature difference, but with the foam that doesn't happen. Maybe a small layer of the insulating material would be enough to stop the condensation? Will lower the extremes of temperature, reducing how much it breathes.

I'd also put just one drain hose in the bottom, maybe with a loop in it to prevent direct flow inwards. Worst case, you can plug the hole if it doesn't help.

 

[jorogi]

However, no salt on our roads.

Lucky sod, we get salt and brine.

And who'd a thunk it, our salt comes from China.

 

[Susquatch]

Yup, nothing like living in a rain forest next to a 10^100000 cubic kilometer salt water puddle. Lucky easteners.

Or 150 yards from a tidal estuary that changes from fresh water to salt water twice a day. Coupled with an average of 170 days of rain per year. 52 days so far in 2025. However, no salt on our roads.

Sorry guys, poorly worded on my part. I only meant the Prairie guys who get no dew. I had thought the no dew qualifier would disqualify the Pacific folks. My apologies.

Another idea, think about what they do to toilet tanks these days, lined with foam inside.

This might help. At a minimum, it might stop moisture from condensing in volume on the box walls. But it won't stop it from condensing on the contents.

@Chicken lights - do you have enough spare battery power to heat the inside of the box a bit during the night? Think golden rods in a gun safe. All it takes is a few degrees to keep the air in the box warmer than the air outside which lowers its relative humidity. The warmth will accelerate corrosion, but it's better than maintaining a wet environment in there. It would only take a few watts.

Or maybe a heater at night running on 115, and a separate heater on 12 (or 24) while on the road.

The styrofoam idea would be beneficial to a heater based humidity reduction system.

I'll keep thinking about it.

 

[Chicken lights]

Sorry guys, poorly worded on my part. I only meant the Prairie guys who get no dew. I had thought the no dew qualifier would disqualify the Pacific folks. My apologies.



This might help. At a minimum, it might stop moisture from condensing in volume on the box walls. But it won't stop it from condensing on the contents.

@Chicken lights - do you have enough spare battery power to heat the inside of the box a bit during the night? Think golden rods in a gun safe. All it takes is a few degrees to keep the air in the box warmer than the air outside which lowers its relative humidity. The warmth will accelerate corrosion, but it's better than maintaining a wet environment in there. It would only take a few watts.

Or maybe a heater at night running on 115, and a separate heater on 12 (or 24) while on the road.

The styrofoam idea would be beneficial to a heater based humidity reduction system.

I'll keep thinking about it.

You know the lightbulb in the fridge trick for welding rods? Same idea, someone tried it on a couple trailers but the boxes don't have the insulation to allow the lightbulb to do anything, temp wise

 

[whydontu]

Wild-ass idea. These are the storage boxes behind the cab, on the frame sides? Big metal box for straps and miscellaneous stuff?

You have this enormous heat source, burning fuel to move stuff around the country. Most of the energy from the fuel goes out the exhaust, and the engine is surrounded by a lot of very hot water. Included in these tons of machinery is a bunch of plumbing designed to reduce the engine temperature and, when needed, increase the temperature inside the cab.

Grab an automobile heater core from a wrecker, mount it tightly against the side of the storage box, and run coolant from your cab heater system through it. Feed the heater core in series with your cab heater, downstream so it’s only getting the excess energy left after the cab is heated.

 

[Susquatch]

You know the lightbulb in the fridge trick for welding rods? Same idea, someone tried it on a couple trailers but the boxes don't have the insulation to allow the lightbulb to do anything, temp wise

The light bulbs are just a low power heater. Anything that warms up the inside will help as long as it isn't combustion which usually adds moisture.

Dew or condensation forms when the relative humidity reaches 100%. Air holds water Vapour in a very strict relationship to its temperature. Warm air holds more water than cool air does. If you cool warm humid air, the air reaches the point where it can't hold the water anymore, so it starts to condense on surfaces.

The idea of the heater is to keep the air in the box warmer than the air outside the box. This lowers the relative humidity inside the box which prevents condensation from happening.

The heater can be any electrical load from a light bulb to an ordinary resistor or even a piece of nichrome wire. The golden rods used in safes are just a piece of nichrome inside a tube.

 

[Tom O]

Out here we got