Convertible Waterproofing external rear camera: Conformal Coating & silicon goop?

[professorman]

I have a Viofo A129 Plus Pro Duo which I love, but my car is convertible. I quickly found out that the camera does not stay on the rear glass, and kinda useless when the glass is folded down. I want to mount the camera to my license plate area.

I am considering pulling the rear camera apart and coat the electronics with Conformal Coating (silicone type $14 on amazon).
There are several different conformal coating. I was trying to decide between silicone and urethane conformal coating. I picked silicone for the increased temperature range. I plan to coat ll the electronics with several coatings, then use RTV to coat the entire entire inside of the housing. Then use ceramic coating on the glass lens.

I am wondering why has no one attempted to waterproof these cameras? It shouldn't be hard to waterproof electronics. Thoughts on this approach? Anything else I should consider?

 

[SawMaster]

Welcome to DCT @professorman

There's a bit more to this than just waterproofing which is why you don't see many dashcams with a waterproof rear cam module (although there are some made). The CMOS circuitry at the sensor generates quite a bit of heat which must be dissipated so the components do not burn out or the signal become distorted before it goes to the cable heading to the recorder. This is usually done by convective airflow through openings in the cam module body which is usually enough, but to gain waterproofing those must be closed off, and then the electronics can overheat and fail. Plus anything covering the elec tronic components now has to transfer the heat they generate to the cooling medium (air) so not just anything will do here.

The higher the performance of the CMOS and sensor such as using 4K versus an analog sensor, the more heat generated. The reason back-up or reversing cams work with waterproof cam modules is that they are not running constantly so there's less time for heat to build up. But with a dashcam they run for hours and thus will be operating at maximum temperature constantly, which requires a different approach. That heat also affects the lens and lens mount too, causing focus shift if the usual parts are involved.

By now it should be clear why your approach isn't likely to work for long if at all. If you're still desiring to try I'd suggest that a better approach would be 'potting' the electronics with epoxy which acts as a heat-sink as well as a thermal mass moderating temperature swings and leaving the cam module body openings intact so you still have airflow. Rather than a coating directly on the lens a protective optically clear cover would be better, as it would be replaceable should it get damaged. Also be aware that silicone and most glues 'off-gas' during curing, and those fumes will leave deposits on the lens as well as alter the coatings used on them, effectively ruining the lens. The 'offgassing' may not be a one-time thing during curing but continue awhile as the cured adhesive or coating gets heated in use.

Far easier and better to just buy a cam which offers a waterproof module for the rear- at least then you can have some assurance that it will perform properly and endure. There aren't many available yet but they do exist.

Phil

 

[Len Dennis]

I have a Viofo A129 Plus Pro Duo which I love, but my car is convertible. I quickly found out that the camera does not stay on the rear glass, and kinda useless when the glass is folded down. I want to mount the camera to my license plate area.

Why not stick it to the back of the roll bar? Assuming you have one (I do but I don't have the rear facing version).

 

[HonestReview]

A convertible has no mounting points for a rear camera.

1. Buy a waterproof camera but you'd need to mount at rear of car around license plate. Could run cabling through trunk.

2. Mount both cameras on the front glass.

3. Build a waterproof acrylic case to hold camera and then find a spot to mount on the vehicle.