Just InCASE
Executive Summary:
Due to extremely low temperatures during wintertime, phone batteries with lithium-ion cells cannot function to their full capacity. In continuing to use a cell phone under these conditions, the user can unwittingly cause permanent damage to the battery. Current solutions, such as relying on body heat or insulating pouches, limit mobile phone accessibility and often add excessive bulk to the phone.
After conducting an initial survey of Dartmouth students, we found that 83% of the 63 respondents who have previously lived in cold climates encountered similar problems and 90% of all 74 respondents reported feeling irritated when their phones die unexpectedly.
To combat this problem, we designed a mobile phone case that heats a phone’s battery with an electrical heating pad. By using a built-in temperature sensor and auto-shutoff system, our proposed solution prevents electrical overheating and allows the product to achieve our top priority of being safe, legal, and ethical. Our product keeps all of the phone’s features accessible and is rechargeable, so customers can easily reuse the heater. We also worked to reduce bulkiness by using compact parts. The target user and purchaser demographic for this product is people living in cold climates who need to use their phones outside in subzero temperatures. Through quantitative testing and analysis of battery lifetime under normal and freezing conditions as well as qualitative user-feedback responses, we evaluated heating and insulating methods in our prototypes to derive a final product.
To achieve our desired product by the end of the term, our group shared research and data analysis responsibilities, given the breadth of information needed to create a successful end product. Based on personal interests, we delegated specific responsibilities to each member, ranging from circuit design, SolidWorks prototype production, Arduino coding, baseline and prototype testing, and project logistics management.
Our final prototype was able to meet all of our initial specifications except for durability. Since we mainly focused on the electronics and heating functionality, our prototype’s external protective structure was not yet developed enough to quantitatively measure durability via a drop test.
The main components we would aim to improve in the future include further reducing the bulkiness by printing a smaller circuit board and using a more compact type of battery, as well as increasing durability and sustainability by using alternative materials and improving the structure and design of the case.
Our looks-like prototype
Our works-like prototype
Our works-like prototype testing results16 November 2021
12 November 2021
30 September 2021
21 September 2021