Electrical Wiring Part II

Junction box ready to be mounted

Wiring block complete with 3 2 pole relay bases and 2 terminal blocks

The wiring block "wired"

The mounting process

The finished product! Complete with battery leads out the bottom of the box and the solar panel leads out the top of the box.

Top of the junction box: 2 module switches and a charge controller

For the first build our cooler simply used TE module 1 and fan set 1. Also, we did not really incorporate the circuit for solar panel either. Our next step was to wire up the entire circuit, test it, and finally make it look good. I purchased am (8" x 8" x 6") junction box housing from Lowes wherein we would mount all of our wiring. I also purchased new terminal blocks. After reconstructing our wiring schematic in Visio, I drew up the wiring diagram in AutoCAD LT (2009 if you care). With both of those pages as our guide we went to work wiring everything up. Due to time and financial constraints we were using 3 donated relays when really we could have used just 2. We needed a total of 5 poles for the circuit. We have 3 2 pole relays. Essentially what happens is this:

• the cooler will turn on if the main power switch is on AND if the temperature controller concurs that the interior box temperature is above the set point.
• Only one module will turn on if only the solar panel is connected. This module should be able to maintain the box temperature at less than 40 degrees in 80 degree temperatures. As long at it is sunny of course. If the box temperature is sufficiently cold than the solar panel will charge the battery (if it is connected and if the right switch is on).
  
• If the battery is connected (12 volt/70 Ahr) then the user can decide if he wants one or two modules running. Ideally the only time you would need activate two modules would be to bring the box temperature down. You could avoid the excess battery drain of both modules by placing cold items into the cooler or by adding ice. A switch controls the activation of module 2. If this were a product we were mass producing module 2 would be activated at the time the user supplies an exterior power source (12 volt car adapter / AC home adapter).
  

After getting our logic all straight we wired it up and mounted the block to the box and the box to the cooler (easier said than done).