Phones have become a part of daily life. So, it’s no surprise that a charging station would be a useful resource on a high school campus. Our goal is to build a renewable energy powered phone charging station on campus accessible to everyone.
Earlier in the term, we collected data on phone battery usage at the school and found that the average phone energy usage per person was about 1152 mAh each day. An additional survey showed that over half of the respondents would use the charging station on a daily basis, indicating that it’s a clear need for students and would be used often.
Our design will be using renewable energy to reduce part of the school’s energy usage, and it will also spread awareness of how much energy it takes to charge your phones per day, since we’ll include an LCD display.
Step 1: Wind Vs Solar Energy
We had many different views on whether we should use wind or solar energy.
The main advantages of using wind power were that it can produce power day or night, it doesn’t need to be regularly cleaned, and it only needs 5 mph wind to be effective. Luckily, our specific location in NH gives us an average wind power of 6+ mph.
Since we wanted it to be somewhere in/on a certain building (where the phone chargers would be used most often), we realized we could not do solar because trees would cover it with shade, leading us to decide wind power was our best option.
Step 2: Capacity Research
The turbine we’ve chosen is a vertical moving turbine. This means it will be less affected by wind turbulence, it is more sturdy, and will need less maintenance.
It will be able produce up to 50 watts of power, transmitting 12 volts of energy. When this statement is broken down, it translates to the production of 4 amp hours/hour. This is based on the equation for finding amp hours: Ah = Watts/Volts. So, the 50W turbine, divided by 12 volts, will equal 4Ah/hour.
The wind turbine will produce 50W of power at full potential for an estimated 16/day. Considering that the turbine will produce So 4Ah an hour times 16 hours is 64 Ah a day, much more than the required 35Ah to fully charge the battery.
Knowing that around 20 people would be needing to recharge 1155 mAh of battery each day lead to the necessity of providing at least 23100 mAh, or 23.1 Ah of energy through our battery. Since this was a rough estimate and it is good to be more rather than less prepared, we chose a battery with the capacity of 35 Ah storage.
Energy/Person 1155 mAh
Energy/Day 23100 mAh or 23.1 Ah
We already had a 70Ah battery, so we decided to use that instead, knowing it would exceed our needs rather than fall short.
Step 3: Wiring the Station
Wiring the station is a very important step in building the charging station so that the right amount of charge gets to the phones and don’t overload it and fry the phone.
We used 20 gauge wire, each charger was independently wired so that if one went down, the rest of the chargers wouldn’t go with it.
We split, stripped, and tinned the ends of 5-foot lengths of 20 gauge wire and attached anderson connectors to one end. The other side was stripped and tinned and a heat shrink was put on the end to later cover the wire and the phone charger.
Step 4: Build the Phone Chargers
We had 3 types of phone charging cables: micro usb, iPhone, and a USB port for any charger someone could bring. We had 3 micro usb cables, 3 USB ports, and 4 iPhone chargers.
The first step was to cut off the USB end of the cable and tin and solder the red wire to a fuse, and the fuse to the red end of the 20 gauge wire, the black wire to the black end of the 20 gauge wire. We used 3 amp fuses for the micro USB cables and 2 amp fuses for the iPhone cables.
Then we pulled the heat shrink up from the 20 gauge wire to the spot where it’s connected to the phone charging cables and shrink it.
Step 5: Create the Station
As the class talked more about the practicality of the bench and the social spaces we want to create, we decided to do some more research by scoping out Gillespie and the social spaces it currently has.
In the main space, there is a large white wall that separates the the kitchen behind it. This is somewhat of a dead zone in the room. The idea of a bar was proposed, that might function as the charging station, an eating area, and a new social hub.
The bartop will be 10ft. by 24 inches. There will be five charging ports spaces two feet apart, three charger options at each port. Spacing will allow work and eating space. There will be an iPhone 5 charger, micro USB charger, and a USB power port for any other charger that is not supplied. At the end of the bartop there will be a wireless charging pad for phones that allow it (a Qi charger).
The wood we picked is walnut, and will come 14 inches out from the wall. It is six feet long and two inches thick. We are going to drill some 2 inch holes to thread the charging ports through. The bartop will be mounted on the wall studs using heavy L brackets with bolts.