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Writer's pictureDaniel Eisenbraun

Week 30 : 3/13/2023 - 3/20/2023

Continuation of Testing

-4.4.1 : Additional Testing

Following week 29, an additional 4.1.1 test was performed on 4/18/2023 under cloudy conditions to verify 130% above ambient specification could be met and to see effects on the battery level throughout the day. Due to the low sunlight exposure, the interior of the car only rose to 109.29% above ambient and had little effect on the battery level of the Test Vehicle due to the excess amount of power provided by the solar panel even under cloudy conditions. Both tests performed meet our 130% max specification for temperature for our High Level Engineering Requirement.




-4.2 : Battery Life Duration Testing

Using data gathered from the first and second 4.1.1 test we can conclude that, when the sun is out, the device is more than capable of running for 8 or more hours depending mostly on the angle of the sun relative to the solar panel and power draw from the battery. On 3/14/2023 the battery level did not dip below 89.5% of the maximum charge of 14.4V (the lowest charge allowed being 12V) with the lowest recorded voltage being 12.9V at the start of testing. Only on the cloudy day of 4/18/2023 did the battery level drop to a point where fewer fans were active per our design, and this was only after 6:00pm when the angle of the sun and cloud coverage had reached a point where they did not provide sufficient power to keep the battery charged above 12.6V.


-4.5.1 and 4.5.2 : Battery Level Monitoring Testing and Automatic Shutoff Testing

Following the test performed on 4/18/2023, at 7:00pm the solar panel was disconnected and the device was allowed to run for as long as possible in order to drain the battery to it's lowest level of 12V and verify that the number of active fans dropped in accordance with our engineering requirements. The unit ran for nearly 30 continuous hours with most of that corresponding to "Battery Level 1" or only having 33% of the rear fans, and 40% of the front fans active due to the charge of the battery being below 12.3V. Battery levels 3 through 1 were confirmed accurate. At Battery level 3 (Battery Voltage ≥ 12.6V), the number of active fans was 100% for the front and back. At Battery level 2 (12.3 ≥ Battery Voltage > 12.6V) 66% of the rear fans were active and 80% of the front fans were active. Lastly at Battery Level 1 (12.0 ≥ Battery Voltage > 12.3V) 33% of the rear fans were active and only 40% of the front fans were active thus meeting our requirements for switching based on battery level.


Following the 30 hour mark, an issue was revealed related to our Automatic Shutoff Capability. At the 30 hour mark, the PWM was reading 12.0V and the DMM read 11.97V.

Assuming a slight inaccuracy with the ADC, the unit was left to run for a bit longer. After checking again sometime later, the PWM voltage had dropped to 11.9V and the DMM read 11.86V. Despite this, the fans continued to run indicating our threshold voltage for the shutoff within the code must be changed to meet our requirements.

Updated ATP

ATP was updated with results of testing and slight changes were made to clarify testing processes for 4.1.1 - that being a reference vehicle is not needed to test if our device can keep the internal temperature of a vehicle at or below 130% of the outside ambient air temperature.


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