Week 14 (Nov. 28, 2018): Pres. #3 (Final Design Specs.) Day 1 – Battery Life Calc. & Component Wiring

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The first set of Final Senior Project Presentations (Presentation #3) were delivered today. While we weren’t able to present today due to time running out, we found that we could improve some of our slides, namely our component wiring connections slide. Our improved Presentation #3 slides are found in the Week 15 blog post.

To review: The Small-Scale Track team is planning to construct a Y-bend located in the middle of the track, and then together, we will create and install at least two induction charging stations along the Y-bend, acting as a sort of “pit stop”. Induction charging modules consist of two pieces: the transmitter and the receiver, and so the transmitter will be the one attached to the station while the receiver will be attached to the side of the pod car so that it will be in close proximity with the transmitter when the pod car makes a pit stop. We bought both the 12V, 600 mA and 5V, 2A induction charging modules, just in case one does not ultimately work out. However, we will try the 12V, 600mA one first. So, in this case, we must buck down (step down) the voltage to around 7.4V, the battery voltage, and increase the current to at least 1.5A to achieve a decent charging rate (“fast-charging” cell phone adapters are rated at 2.1A).

A graphical flowchart depicting the wiring of our components is shown below. A description of the wiring directions of our components is as follows:

On the station, a power supply (either a battery pack or a wall wart) will be providing power to à the transmitter; On the pod car, the receiver will receive the transmitter’s voltage at a certain current (calculation to follow) à the receiver will be connected to the input of the TPS53313 voltage regulator-current amplifier IC à the output of the TPS53313 chip will be connected to the LiPo battery charger, providing the charger with power à the LiPo battery charger will be connected to the LiPo battery on the left side and to the load (the ESC) on the right side à the ESC (Electronic Speed Controller) will be connected to the gimbal motor to control it. The Arduino will most likely be powered via the LiPo battery as well.  
 


Additionally, we had to ensure that the induction charging would be able to charge the batteries and charge them fast enough to switch them out should they run out of energy during Maker’s Faire. The battery life of the 7.4V, 2600mAh LiPo battery is calculated below.




Source: Battery Life Calculator 
Source: Battery Charge Time Calculator

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