Storing a Car Outdoors in Rainy Vancouver, BC: Keeping Interior Humidity Low...

C

Cdn17Sport6MT

Joined
Sep 30, 2017
Messages
1,307
Location
Vancouver, BC Canada
I am currently storing my 2017 Mazda6 outdoors, here in Vancouver. It rains a lot. My car has intact door seals, and there is no indication that any body seam sealer caulked lap joints are leaky.

I have one 40 watt incandescent bulb going continuously in the interior... and a 25 watt incandescent going in the trunk. The pass-through seatbacks to the trunk are cracked-open about an inch or so.

Prior to when the car is turned-off - I set the HVAC to recirc... so though the outside air duct is not 100% shut-off... it is at least mostly shut off.

I have THREE (3) Dry-Z-Air units (!) placed in the car... and I have a humidity gauge that I KNOW works. Said gauge indicates between 80 and 95% relative humidity!

What in the HAY is going on, here, for the RH to be so high? What am I doing wrong?

Do the Dry Z Air pellets become ineffective?

I do know that a total of 65 watts (total) of incandescent lightbulb producing heat is squat compared to the cooling surfaces. But shouldn't that help?

Please, All, tell me what to do to get the RH down to 50 to 60!
 
I live in the same climate region and I never have done anything special to dehumidify the interior of outdoor parked vehicles other than make sure the climate system is set to fresh air intake and not recirculate, and also leave the windows down just a tiny crack. Far enough down for a tiny bit of airflow, but not allow rain in.

I also put a wire mesh around the air intake of the engine to keep mice and rats from nesting in the air filter box, but I do that regardless of where the vehicle is parked.
 
I've always set the air intake to recirculate to close it off from the outside instead of fresh air mode. I'm also going to try wrapping the wheels next time since direct rain water on the calipers seem to cause rust jacketing which eventually leads to some areas of the rotor not wearing evenly.
 
I have a carport in Central Virginia and my motorcycle still gets condensation on it in the morning and on rainy days. I tried covering it and that just made it worse.
 
I’d worry more about making sure there’s minimal organic material inside the car (food, dirt, etc). Close it up and leave it be. Cars sit on car lots and don’t have any mold problems. Ive never heard of keeping lights on in the car. How long are you storing it for? Are you sure there’s no leaking going on? Sunroof, around the windshield/back glass, around where your extension cords are entering the vehicle? If
you are that concerned you could set a dehumidifier on the seat and have it drain outside the car or empty the bucket as you have access to power.
 
Last edited:
Cdn17Sport6MT said:
I am currently storing my 2017 Mazda6 outdoors, here in Vancouver. It rains a lot. My car has intact door seals, and there is no indication that any body seam sealer caulked lap joints are leaky.
Click to expand...
How is storing it outdoors any different from just driving it outdoors. It's exposed to the elements just the same. No 3 year old car should have any issues requiring you to do anything. And for heavens sake, don't leave illuminated light bulbs inside or you may wake up to it burned up.
 
Thank you for the responses, which make sense. Re the light bulbs, each is mounted in a ceramic light bulb "flange" / base, which is mounted on a piece of 2 X 6. Each bulb is covered by an inverted large dia. ground coffee can, which is elevated off the 2 X 6 (for an air gap at the base) and has three decent-sized holes drilled in the flat top... so that the bulb is nominally shielded, but air ingress occurs at the bottom and egress through the holes at the top. If the bulbs should explode (pretty unlikely, and particularly so with the bulb base underneath the source of heat) it is in a metal can of pretty big diameter and height. Limited means of egress of pieces. Limited risk, in my view. Also, in operation the surface of the can is not hot, by any means.

The "cord" comprises a flat-strip insulated two-wire... very, very flat - that enters the vehicle across the trunk seal, at the bottom-position of the trunk opening. It is NOT allowing any appreciable air or moisture into the trunk.

Obviously I have to drive the vehicle more often (it is currently unlicensed and I take it for a highway-conditions spin every 1.5 mos. or so with a permit from the motor vehicle licensing body). An often-used vehicle, by comparison, does not seem to suffer this high humidity interior condition, provided that there are no leaks.

Still, you would think that by adding a mite of continuous heat - and having plenty of desiccant in the vehicle - the RH would not climb to 80 - 95%....

Thank you for all of your responses. Any other ideas... TIA.
 
This seems way, way, way over the top. And it wont even solve the perceived issue.

In order to lower the RH, all that water needs to go somewhere.
A desiccant could work.
A dehumidifier with a functional drain could work.
Functional airflow to the exterior could work if the exterior RH were lower than that of the car interior.

A lightbulb in the passenger compartment and trunk will do nothing if you don't have a means to actually lower the moisture content of the air in the vehicle.

If this were me I would park it and walk away.
I would need evidence of a problem in order to take action.
Claims from a friend or colleague that they had an issue on a different vehicle in a different circumstance would not count.

Cheers!
 
Over the top or not... I DO have some Dry Z Air desiccant in the car, with the collection pails. Still 'real high RH. The stuff does NOT seem to work, at least per my RH gauge. The heat source in the car may actually exacerbate matters... in that the amount of water in the air in the heated sections will then be higher than that in the cooler sections (e.g. inside door cavities)... so that water vapour could condense onto those colder surfaces, I suppose.

I am ONLY worried about corrosion on electrical contacts... as some information I had seen in past indicates that at over 40% RH corrosion forms on bare steel; lower... not so. Now crimped cad plated open barrel connectors... crimped onto stranded copper wire - are not bare steel, per se... so I may not experience issues.

I would just have thought, though, that the Dry Z Air unit would work well. It does NOT appear to.
 
I’d also get a 2nd humidity monitor. 90% RH is very high. It’s almost raining in the car at that point. I’m not sure there’s really a problem unless you have a leak somewhere.
 
I'm still confused about all the fuss here. I live just south of OP, and literally right on the salt water on the north end of a bay where salt water and rain blow in sideways. I've never done anything more than leaving a tiny crack in the window and leaving the recirc open. Never had any mold or rust inside a vehicle, no matter how long it was parked. YOU WILL 100% ALWAYS get too much condensation inside if you don't allow for a tiny bit of airflow in and out. I have plastic bins outdoors with tools in them. The plastic bins have holes on the bottom and are not air tight on the top, but keep the rain out. Tools never rust and it's bone dry in there at any time of the year.

Airflow + no rain getting in = you are golden!
 
Cdn17Sport6MT said:
Thank you. I will confirm the RH... with a second RH indicator. Also, I will open Recirc so that it exchanges readily with outside air.

Thx!
Click to expand...
Also look into whether or not your air intake is vulnerable to mice or rats nesting in the air box. They will chew up your air filter, and possibly go deeper towards the MAF. They will also chew wires in the engine bay to wear down their teeth. Rodents are not common issues, but when the vehicle is parked for a long time, they will nest in there if they can.

I used to keep a Subaru parked for long periods in Kitsilano when I lived there for school. Had to deal with this issue.
 
They have already chewed at some wires... I have resorted to putting about 5 of the smallest-sized baby food jars - each with a chunk of a urinal puck in it. That has been relatively effective. The air intake is blocked-in with a piece of urethane foam... not as effective, of course, compared to metal mesh... but that has not been a problem.

Thank you for the response...
 
I let a vehicle sit for over a year with a short drive every few months. It spun a bearing and it took me that long to decide on and install another engine. Mold grew on the carpet, seats and console area. To this day it smells like mold and I've cleaned everywhere I can think to clean. I believe the biggest problem was the ground underneath it that occasionally got wet. I notice that if I park a vehicle on the ground, after a few days it will smell musty inside. Not so if I park on pavement or concrete.

Squirrels attacked it, chewed up fuel injector harness, parts of the manifold, mirrors and roof rack. I now have a pellet rifle with a scope and my daughters think I'm cruel.
 
I don't think keeping a heat source inside a shut up car is going to work. Condensation forms on surfaces that are colder than ambient, which means water will condense on the inside of your windows. What you really need is a dehumidifier that you empty periodically, or a place under cover where you can crack the windows with a heat source inside.

What will do the most to prevent the nasty's from forming, like RhondaHonda mentioned, is making sure as much organic matter is removed from surfaces inside the car as possible. If you see any mildew on surfaces clean it right away with hydrogen peroxide.
 
There have to be times when it's dry there. Roll the windows down, particularly on cold, dry days. Those have the lowest absolute humidity. Then roll them back up to "trap" that dry air.

My Biscayne is parked for the winter under a tarp (yuck!) but with a bucket of DampRid on the floor. Those crystals attract water that then drips down into the lower part of the bucket. We'll see come spring if it worked!
 
eljefino said:
There have to be times when it's dry there. Roll the windows down, particularly on cold, dry days. Those have the lowest absolute humidity. Then roll them back up to "trap" that dry air.

My Biscayne is parked for the winter under a tarp (yuck!) but with a bucket of DampRid on the floor. Those crystals attract water that then drips down into the lower part of the bucket. We'll see come spring if it worked!
Click to expand...
Did it work?
 
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