About the Chassis...
Hindsight
In my first attempt at building this camera my plan was to try and minimize cost by building my own electronics enclosure. A sheet of acrylic was much less expensive than prefabricated boxes. In hindsight, however, the time spent in building that box offset any savings in material expenses. And because the original box also served as the solar panel support it wasn't sturdy enough to withstand the stresses it was subjected to. Visit the frame page to read more about the shortcomings of the original enclosure.▼
And Looks Too
While shopping around for prefabricated boxes to mount the electronics inside of I found an electronics store with a wide selection of chassis in different shapes and sizes. I resisted the expense of these chassis thinking I could build a more suitable box for less cost. But once the camera design was modified to separate the solar panel support from the electronics enclosure the off-the-shelf chassis made more sense. Besides the convenience they offered they also had the added benefit of being made from aluminum which is in keeping with the goal of ending up with a weather resistant finished product. Aluminum is also used in the composition of the solar panel support frame so the look of the electronics enclosure compliments the frame. Form followed function in the design of this camera but aesthetic appeal is always a welcome feature.▼▲
Size Matters
The size of the box was selected to provide enough room for the battery but to also have surplus space for future upgrades to the electronics suite. Premanufactured boxes come in a select variety of sizes and the width of the chassis is the default width that comes with a box of this particular length and height. The height of the enclosure is slightly higher than the height of the tallest piece of electronics it houses which is the battery. The length of the chassis is about 1/2 inch less than the length of the support frame but the tabs on the lower frame pieces provide just enough shelf to hold the chassis up slightly above ground level. I imagined a worse case scenario in which the power source was subjected to a shallow pool of rain water. Elevating the chassis provides an extra degree of protection from the elements for the electronics inside the box. And, as if that wasn't enough, the charge controller sits on top of T-stands glued to the inside bottom of the box further elevating it above water level. The battery rests right on the inside bottom of the enclosure but is made of plastic and is sealed so the likelihood of it being damaged by water is small. Soft plastic self-adhesive pads are attached to the outside bottom of the box to protect it from scratches while working inside it. These pads also serve to give the box just enough finger space between its bottom and the ground so portability is enhanced.▼▲
Holes in the Plan
Unfortunately it doesn't seem possible to have a completely waterproof box. It has to have some means built into it for letting wires pass through so power can get from the solar panels to the fan and battery, and from the battery to the camera. "Panel connectors" provide that means and also make it possible to disconnect the wires from the outside without the need for removing the lid from the box. Holes had to be cut into the sidewall of the box to mount the panel connectors into, but the excess space around these openings is sealed on the inside with silicone to add some weather resistance back into the enclosure. Two more holes were cut into the sidewalls for the optional ventilation system. One hole serves as the make-up air opening while the other hole is where the ventilation air is discharged. The air discharge opening is protected from bug infiltration with a piece of aluminum screen. The make-up air opening is protected from dust infiltration with an air filter that clamps in place. The clamping mechanism requires four more very small holes to be drilled through the chassis wall at each corner of the filtered opening. The lid itself has two small screw holes drilled through it so it can be fastened to the box. Weatherstripping was applied along the edges of the underside of the lid. The top edge of the box will press into the weatherstripping when the lid is put on which creates a somewhat airtight seal.▼▲
Don't Come Unglued
I wanted to minimize the number of holes drilled through the box so instead of mounting the electrical components by screwing them into the walls of the box I epoxied nuts onto the inside walls. There are three small nuts glued to the sidewall for mounting the ventilation fan to. There are four t-nuts glued to the bottom of the box for mounting the charge controller to. Since it will need occasional replacing I made the removal of the battery more convenient by simply using velcro to fasten it to the bottom of the chassis. There are two disconnect switches mounted onto a short piece of steel angle. This steel angle is attached to the box sidewall with double sided mounting tape.▼▲
Testing 1, 2, 3
Before mounting the camera and connecting it to the power source I tested the frame and chassis assembly to see how it would fare against the elements. The perfect opportunity presented itself when I set the assembly up on the roof to recharge the battery after it had sat for a while unused. Coincidentally, a storm moved in the next day and brought a significant amount of rain with it. My daily schedule prevented me from retrieving the assembly from the roof after that storm so it sat up there for several more days. Two more storms passed through during the following days bringing more rain and truly testing the integrity of the power source assembly. When I was finally able to get back on the ladder and pull the solar panels down I removed the chassis lid to inspect the conditions of the electronics inside. The amount of wear was exactly as I had expected. A small water stain was on the inside bottom of the box leading from the ventilation make-up air opening. I worried that that opening would allow storm water in and was reluctant to cut it but I couldn't think of any other way to get the box to breathe. But judging by the size of the stain the amount of water that got in was harmless and I'm no longer concerned about storm water posing a danger to the contents of the box. Some dust was also noticeable inside the box but I attributed that to high winds that came with the storms. They likely pushed the dirt and air past the filter (or the fan) with more pressure than was intended which would explain why the filter failed to prevent that debris from entering. All in all I'm satisfied that the final chassis configuration will be able to withstand the worst of the storms that my end of the world ever sees.▲
