Roof Console

Hello and welcome to post 2 of my in-car PC build :)

In the first post, I set the design requirements for the system then designed and built the PC. In this post I'll go through how I found a way to mount it in the car.

I had a few problems that I needed to solve in order for the computer to work reliably for a long time (Expected life of the computer is four years before i'd be looking at doing a major rebuild). They are:

• How to minimize the impact of dust, water and heat on the computer's performance
• How to run power and wiring for all the peripherals to the computer
• How to make the computer easily accessible and serviceable without being intrusive

To keep the PC as far away from dust and water as possible, I chose to have a roof console custom made. A roof console is basically just a narrow box that attaches to the roof of the car and runs from the front of the car backwards down the centre. They are normally used for extra storage and mounting 2 way radios, reading lights ect. This choice is a trade-off as being the highest point in the cabin it naturally gets the hottest and will absorb heat generated by the sun shining on the roof. However the protection from water and dust, while also being in a position where it is out of the way was worth it.

After doing some research I found an Australian company that specializes in designing building roof consoles (and other interior accessories) called Department of the Interior.

Under my guidance, we designed a console to house the computer. I had to have the PC shipped to them so they could use it for measurements. The console we designed (I modified one of their off-the shelf designs) and attaches using the mounting holes from the car's factory fitted roof console. I also had them put in some switch slots as I needed the spots for switches for the computer and other electrical accessories.

Prototype design of the console

A few weeks and several hundred dollars later the console arrived and I could resume the build.

Underside view - you can see the computer mounted in the console. As an added bonus the wooden construction should help reduce vibrations from the engine being transferred into (and thus damaging) the PC's components.

Installing the unit into the car was slightly complicated; First I removed the rear view mirror and the factory plastic console that housed the sunglasses holder and two reading lights, and unscrewed the factory centre cabin light.

Forward end where the console was, note the two screw holes in the metal plate

Then I removed the sunglasses holder from the factory console and installed it in the roof console. Getting the holder in the right position was slightly annoying, as a slight misalignment meant it would catch on the console and not swing open. This is most likely due to console being hand made and the expansion and contracting of the wood with temperature and humidity.

The console came with a steel bracket on the end which serves to secure the console onto the car. This had to be removed in order to install the sunglasses holder. 

Console with steel bracket removed and sunglasses holder installed

In order to be able to screw the console into the holes in the roof, I had to drill two holes in the  top of the sunglasses holder to access the screw heads.

The next step was to reattach the steel bracket. 

Steel bracket partially attached (2 screws missing). The two nuts  welded onto the bracket serve as spacers and position the console at the correct hight in relation to the roof lining.

The console could now be installed. Installation was slightly tricky. In order to align the two front screws, I had to perch one between the underside of one of the the nuts in the picture above and the sunglasses holder, and the other I held up against the underside of the steel bracket with a screwdriver while the console was lifted into position. Installing the rear two screws was a simple matter of aligning the them with the holes from the factory roof light and fastening them. 

Unfortunately fitting the factory reading lights to the console along with the sunglasses holder was not possible. I have ordered two eyeball type LED reading lights which I will fit at a later date. 

With the roof console fitted, it was time for preliminary testing. 

I have yet to decide on a touchscreen for the computer, so in lieu of this I used a standard LCD computer monitor and a USB mouse and keyboard to control the computer. For a bit of fun I used a 3.5mm jack to run audio from the computer into the car's head unit so I could stream my music online from the car computer while I worked :).

Console fitted with the computer up and running

I hooked up the computer in series with a multimeter set to ammeter mode to get a reading on the current draw of the computer. Evidently the computer is capable of drawing more than 10A, which tripped the safety circuit on the multimeter and caused it to cut power to the computer. However, I did manage to gather the following data between blackouts:

Max observed current: 7.3A

Current when computer is shut down: 0.06A

Current when computer is idling: 1-3A

These are acceptable figures, so I left the computer running continuously for several hours during the day to get an idea of how hot it would get. After approximately 4 hours of running in the shade on a 38C day (100.4F) with high humidity, I observed some worrisome results. Using Speedfan, a free and simple application for monitoring system temperatures and controlling fan speeds, I found the following:

There are several very high temperature readings listed, including the CPU. When I felt the case with my hand, it was very warm to the touch, to the point where the heat had conducted through the sides and bottom of the console (roughly 7mm of wood, foam padding and vinyl) to make them warm also. Better case cooling is required. 

To rectify the problem, I will buy and fit two 40mm high performance fans to replace the ones mounted on the front of the case. In addition to this, I bought two 60mm fans and have fitted them to the black grill on the underside of the console. This idea did not work out as the fans would not fit on the grating without hitting the end of the PC when it was installed.

Mockup of 60mm fans which did not get used

Dust is a major concern as the car will be driven through  muddy & dusty environments that are notorious for damaging electronics and mechanical components. I have some  porous packing/cushioning foam from the box that the console came from, which I will fit between the fans and the computer to use as a filter. 

In addition to testing the computer and checking the fit of the console, I also started to run the large amount of wiring and communications cables needed to support the computer. So far I have ran a thick ground wire to ground the computer and accessories such as the reading lights, a thinner red power wire for accessores, two 2M USB extension cables and a figure 8 wire. One wire on this carries +12V that is switched with the park/headlights, and a ground wire that runs back to a variable dimmer unit. These will be used to run the LED's in the carling switches that I will mount in the switch bracket. I also ran two 4 core wires from the console down the passenger A pillar for future use with the switches.

Routing the wires from the console to above the glovebox (There is a compartment above the glovebox in the Patrol that will serve as an electronics and wiring bay) was relatively easy. I removed the A-pillar covers on both sides then removed the sun visors and passenger side roof handles. This allowed me to pull the roof lining down so I could feed the wires above it and leave them hanging out the open area where the switch holder on the console was (I removed it for easier access until I start wiring and mounting switches). 

That's it for this post, I'll write an update as soon as I make progress. Bye for now and thanks for reading.