Interior Box update / Testing

Measuring out the acrylic lip dimensions

The whole cooler

Modified lid stop

Ready for testing

Thermocouple interior mount

Data logger ready for logging

Current interior box temperature (Degrees F)

We are getting close to finishing up the inside of the cooler. We have all of the acrylic cut and painted. All we have left is to mount it into position. One key step was to get rid of Igloo's lanyard which keeps the lid from opening too far. It was a simple fix. With the wiring complete and the interior housing almost complete we decided to do some preliminary testing. We set the cooler up in the laundry room (~ 72 deg F). We activated both modules and set the data logger inside the chamber. The initial chamber temperature was 66 deg F. We are going to let it run all night to see how it functions. We'll see in the morning.

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).

Solar-Powered Camping Cooler Day 5

Day 5:

Due to the time crunch I was unable to construct decent exhaust ducts for the hot and cold air. We spent Saturday digging out foam and constructing quality exhaust ducts. Things were going well until we tried to re-spray foam into the sections we had cut out. We used a common crack sealing foam thinking it was similar to the DOW Froth-pak. We assumed wrong. From the pictures you can see how well the foam turned out. We decided to continue on with the project and fix our foam problem later.

The next step was to construct our interior housing. We cut the side panels first and also cut the duct cut-outs for the interior fans. Then we bent the remaining section of the box. The last step was to paint the acrylic. We chose to paint it in order to hide the yellow interior foam color. We finished the day after we painted the acrylic sections.

Cutting out the old ductsThe interior ducts

Foam job #2: Filling the sections we cut outThe results of our second foam jobCutting the interior ductsEnd sections paintedPrepping the acrylic for bending

Painting the interior box

First Build: Solar-powered cooler

The first build was due today. The class thought it was pretty cool, no pun intended, but there is still a lot of work to do. We let the small module run off of battery power for about 1/2 hour. It lowered the internal temperature from 62 degrees F to 54 degrees F in that time. I guess that is pretty good considering the fact that we need to patch a hole that connects the heat sync exhaust duct and the cold sync exhaust duct! We should have a minimum of an inch of insulation between those two ducts. I must say I think the temperature controller is a great feature to have. It is nice to know the internal temperature at all times. It is also nice that it turns the modules on and off according to your temperature set point.

Solar-Powered Camping Cooler Day 4

Dual terminal block with two-pole and single pole relays

Top View: Wiring layout
Finished cooler housing

Day 4 was entirely focused on wiring all of the switches and controllers together using relays. For the Tuesday deadline, only an initial prototype is required. For the final build the team will purchase two three-pole relays to complete their cooling system. As of now the cooler only runs off one module using battery power. The module turns on only when the on-switch is in position and the temperature controller calls for power. Eventually the cooler will be cooled using two modules when AC/DC power is connected and only one module when solar powered is connected. The system is designed to maintain an internal temperature of < 40 degrees F in an 80 degree F environment.

Stay tuned as the next steps include attaching and wiring the solar panel, connecting the additional module, and cleaning up the wiring and interior housing. All this before the final build is due April 9, 2009.

Solar-Powered Camping Cooler Day 3

Top View: Reverse polarity switch

Top View: Cooler prepped for foaming


Foamed-in cooler

Day 3 started early. I arrived at JBT AeroTech early to spray the foam. After receiving some additional assistance on wiring the polarity switch I sprayed the cooler, carved out external exhaust ducts and then headed home to finish the rest of the project on Monday.

Solar-Powered Camping Cooler Day 2

External exhaust port (incomplete)
Internal wiring layout

Suface mounted switches and controller (On/off, polarity, temp controller)

Day 2 started out well but quickly slowed down. After a successful night of mounting the modules the next task was to mount the switches. I was back at JBT AeroTech on day 2 and I again received helpful advice.

After the switches were mounted I turned my attention to the electrical circuitry. I was lacking a 3 pole 12-volt relay and driving all around Ogden (Utah) didn't prove to be helpful in locating the relay. As the day went on it became apparent that I was not going to have the internal electrical wiring complete for the morning foam spray.

I decided to pull all of the internal wiring to the exterior so I could pour the foam and then address the electrical situation later.

I also needed to complete the external exhaust duct system before I could spray in the morning. These tasks took me all night/morning to the point where day 2 quickly turned into day 3.

Solar-Powered Camping Cooler Day 1

The three cooler models (82 Qt. Coleman Ultimate Xtreme (Green), 100 Qt. Coleman Xtreme (Blue), 120 Qt. Igloo cooler (White))

A collection of all our equipment ready to be installed into the cooler

Brainstorming as to where we should put the 7.5 Ahr battery

Using the hole saw to mount the clear the way for the hot-side fan intake

One module assembly mounted up nice and snug inside the cooler... nice!

The first step was to pick between the 3 different styles of coolers we had received from Coleman and Igloo. We chose the Igloo 120 Qt cooler due to its large size and similar insulating qualities with the Coleman Xtreme series. We were going to need to add additional insulation to whatever cooler we chose in order to minimize heat losses. For this reason the bigger cooler allowed us to add more insulation and still have around ~ 40 -50 Qt capacity. The big accomplishment of the day was to mount the modules into the cooler. I received some mounting advice from a friend at JBT AreoTech which proved to be a great configuration. After drilling though the plastic and insulation things mounted up nice and solid. It made for a late night and a few bloody knuckles but it was worth the effort!