Project
| # | Title | Team Members | TA | Documents | Sponsor |
|---|---|---|---|---|---|
| 14 | HAND CRANK QUICK-CHARGE TEMPORARY CELL PHONE ENERGY SOURCE |
Achyut Agarwal Rubhav Nayak Shreyasi Ray |
Matthew Qi | design_document1.pdf final_paper1.docx final_paper2.pdf photo1.jpg photo2.jpg presentation1.pdf proposal1.pdf video1.MOV video |
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| ## Team Members: - Rubhav Nayak (rubhavn2) - Shreyasi Ray (ray17) - Achyut Agarwal (achyuta2) # Problem In the current connected age, it is quite important to ensure that our electronics are powered at all times, but oftentimes we hear of situations where people are unable to or don't remember to charge their devices. Solutions for emergency power do exist in the form of portable power banks but it's yet another device to remember to charge, and hand-cranked chargers available on the market tend to be large and bulky built for survival scenarios, which is too overkill for the urban youth who just forget to charge their devices and don't happen to be around a wall plug. Furthermore, all the existing devices currently charge the battery via hand crank and that in turn charges the device. This is not efficient as it adds extra points of energy loss (in the form of heat) and also reduces the overall battery health. By implementing a sort of bypass through a switch we can help retain battery health as the user can bypass the battery and directly charge their device and although it increases the complexity of the circuit we believe that this is a good tradeoff as in an effort for environmental preservation reducing battery degradation is important. # Solution Our solution is to build a hand-cranked charger, much like the ones you find on the market, but without all the bulky extra survival features. Plus, we want to incorporate a small battery that can hold around 15-20 minutes of hand-cranked charge, just as a backup for when the individual would not be able to crank the charger. This allows us to keep the size of the device at a minimum, with the whole apparatus being around the same size as a large phone. The crank would prioritize the charging of any load connected, and only when no load is connected, it will charge the battery. Similarly, the battery would discharge only when there is a load connected and the crank is not in operation. This product runs completely off the grid. The battery only charges via hand crank and the product will only have one output. # Solution Components - Crank - Foldable, 3D Printed - Motor - Pololu Micro Metal Gear Motor (12V 120rpm, choice between BLDC Motor or Brushed Motor) exact motor to be decided as per discussions. - Gearing mechanism - 3D Printed (to spin the motor at optimal RPM while requiring a reduced input) - Full-wave rectifier ROHM RFN6T2DNZC9 - (if we use BLDC Motor) - Schottky Diode - ROHM RB095T-40NZC9 (As a stoppage diode to ensure the battery doesn't feed into the dynamo) - 1000mAh battery - ASR00012 - Boost converter - LiPower Boost Converter - USB-A female connector - KUSB-6-3-4-3-6-1-10 - Capacitor - Generic (used as a filter, appropriate capacitance to be determined after ensuring the optimal crank rpm) - Switch - Mouser 490-DS04254201BK-STR -(positioned near the crank - allows us to choose between direct crank or battery output) - 7-segment Display - Adafruit ADA1002 - Microcontroller - Arduino (to display the charge value of the battery + optimal crank speed) ## Subsystem 1 Our entire electromechanical side of the project comes under one subsystem. We connect the crank to the motor via the gearing mechanism. Here, we have two choices for the motor. We can either use a brushed PM DC Motor, which gives us a DC output but with low current, or we could use a more expensive brushless DC motor, which will give us a higher current throughout but can end up becoming bulkier and more expensive, as we then need to add a rectifier and capacitor to ensure the output is DC. The motor is then connected to a diode in forward bias from where it goes to the battery and to the 5V voltage regulator parallelly. The regulator then goes to the USB-A female output. We use the USB-A output for two reasons. The first is to ensure that we can charge a wide array of devices, and the second is to make use of the USB protocol's safety features. Most phones can recognize when plugged into a USB port, and if they notice that the power from the USB port is unreliable/fluctuating, it can choose to not charge the device. While this may seem like a disadvantage at first, it will allow us to confidently test our product without worrying about the condition of our phones. We will incorporate a switch that will control if the hand crank will charge the battery or directly supply power to the USB output. This is to reduce energy loss and also preserve battery health. The switch would essentially direct the flow of current in two places a) the hand crank’s output, b) the device’s input ## Subsystem 2 This is technically integrated into the first subsystem, but we treat it as a secondary system because it doesn't directly deal with charging. This subsystem will make use of a microcontroller to read the voltage of the battery and display its charge level on the 7-segment display like the Adafruit ADA1002, and when the crank is operational, it will display the voltage of the crank. Since the crank speed must generate 5V or higher to be able to provide power, the display will be able to give that information to the user so they know whether to speed up or they can slow down (By displaying F for faster and S for slower). This display will be powered by a battery at all times. It can also help tell the user how much of the battery is charged. # Criterion For Success We will deem the project successful if we can achieve the following: - Hand crank charges the phone - When the phone is not connected, the hand crank charges the battery - When the crank is not used, the battery charges the phone - The 7-segment display outputs the values of crank speed requirements and battery level We will also attempt to keep the size at a minimum, but we also realize that size optimization will not be easy. Even with a larger size, our portable power bank achieves something no other product in the market does with a seamless switch from battery to crank. Our power bank will be more efficient and compact than those on the market. |
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