Week 3 Project Update

Design:
With the design approval, calculations of required amount of materials were established. The quantities of aluminum stock was communicated with the track team. Currently, waiting for a response to determine if more material needs to be purchased from Coastal Aluminum. Confirmed with the track improvement team that the ribs will need to be fabricated according to previously mentioned specifications. Measurement of charging components and supporting hinged box were made to create a Solidwork design. The solar rack design still needs minor improvements to the mating of the two separate pieces before completion.

Procurement/Fabrication:
Position locking draw slider was purchased to match the physical dimensions of the solar rack and charging components. I am hoping to have all designs finalized by the first presentation. With that part complete, fabrication of components can begin that weekend.

T-bar:
A new idea of the modifying the supports proposed to the track team. An additional clamping plate between the T-bar and the 3-bar linkage can shift of the weight of the rack further in towards the center or outer perimeter of track loop to help with any stability issues.

Week 2 Updates

This week, I was able to charge a battery fully to determine the maximum voltage.

The initial voltage of the battery was 7.44 V.

The maximum voltage of the battery was 8.59 V after 67 minutes of charging. Further charging did not increase the voltage reading of the battery. 

Several issues were discussed with the track manufacturing team:

1. Ribs for the solar rack: arc length, radius, amount of pieces
2. Modifications to the T-bar pole mount to allow adjustment of positioning
3. Available materials left over

The controls team was informed of the battery that will be used to power the bogies. A battery was given to Chris, who has a charger, to test the controls using the rechargeable battery. Several more will be given to Luis for backup.

The bogie team was also informed of the battery size. The position of the battery will be inside the cabin.

The design of the solar panel rack begun. Measurements and dimensions of the pieces forming the rack were taken and imposed into SolidWorks. Previous year's T-bar pole mount was mated to the new rack.

A clamp system will need to be implemented to secure the solar panel onto the rack. The battery box design will need to be updated to a box design with a hinge.

Battery Charging Test

The objective for the first 2 weeks of this semester was to test charge the batteries and ensure functionality. Due to weather conditions being rainy and cloudy generally throughout the past 2 weeks, the only window I've found to test the equipment was on Saturday and Sunday. First, I began by checking the voltage of the combined 6 cell battery. The battery's initial voltage was 7.56V.

After about roughly 3 hours with numerous resetting of the charging unit, the voltage of the battery was 8.10 V. These resets were caused by dense clouds or other obstacles preventing the solar cells from producing enough power which results in a voltage drop across the circuit. Due to these resets, the time period of charging is unknown. Future plans will feature a recording device so that the exact time when charging stops will be known. The specifications for the iMAXB6AC states the allowable DC input voltage is 11-18V. The buck converter was set to 17.9V, the highest allowable voltage output (input into iMAXB6AC) to delay the "DC IN TOO LOW" error message which stops the charging process because of the insufficient sun light. According to the manual this error is caused by the input voltage being less than 11V.

Without any battery voltage charge chart, it is difficult to determine the state of charge (SoC) of the battery as the relationship between voltage and SoC is exponential. Only references I found for 7.2V nominal batteries were stating that a fully charged battery would measure ~8.4V. The goal of the next testing session is to determine the maximum voltage the batteries will reach and time it takes to reach this maximum voltage.