Wiring up the boot

As more and more wires stacked up, I did start to wonder where the hell I’d put them all.,,.

We’ve already got the umbilical from the roof carrying 8 wires (6 camera, lidar and the power lead for the beacon). All but the latter needs to connect to the px2 and I can’t install that until the other wiring is in place.

The first thing we did was to wire USB, CAT6 and a HDMI through to the front of the cabin. I’d originally planned a HUD up front, perhaps using the 2nd HDMI on the px2, but I’ve also got a touch screen+ raspberry pi all in one compact case which might make a suitable alternative, we’ll see. Either way, having USB, network and HDMI means hopefully I don’t need to remove panels again in the future.

The wires come out of a cable gland near the bottom of the glove compartment. To remove this you need to remove the plastic pins holding the lid on, then undo the 4 torque screws at the top. There is another torque bolt, underneath the dash that also needs removing before you can pull out the plastic insert. We threaded the cables in the arch between the interior trim and the subframe

While I was at it, I threw in a power cable. The cables come into the boot on the right near the door catch secured in a cable gland and cable-tied to the frame to keep the pressure off the gland (the plastic panel of the wall is fairly flimsy.

All these cables were 4m so the excess at the front was coiled in the glove compartment. At the rear, they are coiled in the spare space at the bottom of the boot.

Next lights. It’s quite dark in the boot (I used a spotlight for much of the work so far). Rather than buy strip LED and have to wire them up I bought some really cheap ‘pimp my ride’ style rgb music activated lights.

I wasn’t interested in the sound activation but more the fact that for £10 i got 4 prewired led bars and a controller that was designed to work with a 12v car battery so should contain its own regulator. It also has a remote that allows the colour to be changed. White when working, blue for showing off. There’s that blue theme again.

Once uncoiled quite a few wires but with the help of Cihan and his magical Velcro cable ties (I’m a convert) we put one bar above the top shelf, one in the top shelf to light the px2 and two down at the battery level. In all cases, the leds where hidden behind framework as was 95% of the cable. The led lights were wired to a switch on the side panel, I then wired up the fans to one of the other switches and the beacon line from the roof umbilical to a 3rd.

I need to install the power distribution in the bottom along with battery and the charger. To do this I need to run a line back from the cars 12v battery back to the split charger for the leisure battery. The main drive battery for the Twizy is under the seat. I don’t want to touch this as it belongs to Renault but there is a small 12v lead acid battery behind the registration plate at the front. It’s used for the standard electrics on the vehicle such as lights and windscreen wiper and is kept topped up from the main lipo drive battery. I need to take a positive feed off this 12v battery back to an intelligent split charge relay so the leisure batteries in the boot can be recharged automatically from the Twizy. When we were installing the cables into the front cabin we spent a long time trying to also route a power cable down to the front battery but although we finally managed to route a cable down through behind the dash, I wasn’t happy about its proximity to the steering rack. After an hour of fighting to get a cable through, I abandoned this idea and decided to go under the vehicle later. We needed to demo in a few days so I decided we could demo on mains and I’d install the DC power circuitry later. It’s better that this power line is separate from the signal lines anyway.

However, to reduce structural work once he px2 was installed, I made some polycarbonate sheets that would hold the power distribution and fuses. On the small front panel I mounted two volt meters and an amp meter, to be wired later. This would show the main incoming voltage from the car battery which in turn is topped up by the Lipo bank of the car. The second one would show the leisure battery voltage and the current meter would show how much current the axillary electronics are using. Yet more parts from frank the robot. Poor frank.

Now it was finally time to mount the PX2. Using the tray I’d built previously, the px2 was installed on the first shelf, the cameras were routed down and the spare cable coiled neatly and hung from the roof of the boot to keep it out of the way. The px2 wiring loom was routed down toward the bottom. There is actually only one cable needed from this, the power, but I wasn’t prepared to rewrite the PX2 umbilical so they can also rest in the space at the bottom. We then connected everything to the mains and booted her up in situ for the first time.

Shes’s alive.