Building the Solar part of the Solar Dino

The small solar electric system powers the dino horn and the rotating dino beacon light. It has some reserve to power future solar additions. Any ideas?

The system consists of:

Two 15 watt, 16 volt PV panels hooked in parallel

A 12 volt lead acid battery (stolen from the lawn mower)

A small charge controller

12 VDC horn and 12 VDC rotating light

Wire, switches, fuse, horn button.

The solar panels and charge controller were from a set I ordered from Costco sometimes back.

The 12 volt battery was stolen from our lawn mower.

The horn is a an "oogah" horn from Harbor Freight -- it does sound a lot like I would imagine a dinosaur to sound -- I guess no one can prove me wrong on this :)

The rotating light is standard rotating amber beacon made for trucks etc. as a caution light.

I thought that we could mount the PV panels on the dino, but we could not find a large enough and safe enough place to put them. So, we moved them a safe distance away and mounted them on the ground.

The rest of the system is installed up in the "drivers platform" behind a plywood panel. A wire runs underground from the drivers platform to the PV panels.

In operation, the horn and light are run off the battery, and the PV panel charges the battery through the charge controller. The purpose of the charge controller is to prevent the PV panels from overcharging the battery.

Two 15 watt PV panels should provide about (15 watt*2)(4 hours) = 120 watt-hours of energy to the battery on a sunny day. This is equivalent to (120 watt-hours)/(12 volts ) = 10 amp-hours a day. So, this would run a 1 amp load for about 10 hours (or a 2 amp load for about 5 hours, ...). In reality, the charging process and getting the juice out of the battery process has some losses, so about 80% of these times might be about right. Anyway, plenty for a horn and light used only a few minutes a day.

The light is turned on with an automotive toggle switch bought at an auto parts store.

I puzzled over the horn button for some time. What I finally came up with is to use the "Dead End" dinosaur sign that we had lying around. It is mounted with a hinge at the top, so that it swings in and out. The horn button contacts are two short pieces of copper pipe that are flattened -- one is mounted to the plywood bulkhead behind the sign, and the other is mounted to the piece of plywood that the sign is screwed to. When the sign is pushed toward the bulkhead, the two pieces of copper come together and close the circuit to the horn. A small piece of spony packing foam between the bulkhead and the sign keep the contacts apart until you push the sign and compress the foam. A large head bolt through a loose fitting hole in the bottom of the sign and into the bulkhead keeps the sign from being pulled out more than a half inch or so, and protects small hands from getting close to the contacts.

Pressing on the Dead End
sign sound the dino horn.

The horn contacts are flattened
copper pipe sections soldered
to wires. The small piece of white
foam is the spring that keeps
the contacts normally separated.

A fuse is used in the battery to horn and light circuit to protect against short circuits. Even fairly small lead acid batteries can provide quite a bit of energy on short circuits, so some protection is important.

The PV panels come mounted on a very flimsy PVC pipe frame. I decided to support these on treated wood 4X4's. The vertical post with cross 2X4 supports the top end and lives in a concrete footing. The bottom end of the panel screws to a 4X4 treated wood piece that is staked into to the ground with angles 2 ft copper pipe. We get some high winds, but these panels are not going anywhere.

Wiring Diagram

Here is a rough wiring diagram for the solar electric system.

I need to clean up the wiring a bit, but is was functional for the first visit.

Gary September 5, 2009