Load Shedding or Rolling Blackout is a very common occurrence in developing countries like India, South Africa, Bangladesh etc.. Load shedding season is not a favorite season to anyone. It greatly affects our day to day activities and mainly our mood :-P
Here is a post about "TOP 10 COUNTRIES THAT HAVE EXPERIENCED AND CONTINUE TO EXPERIENCE CRIPPLING LOAD SHEDDING"!
So here I am, back with a new Instructable which solves the above common household problem to a great extent. I know there are Inverter systems, Generators, etc already available which can solve the above problem. But I intend to create a maker's cost effective solution. I've enclosed this whole project in a Single wooden Box!
Geeks like us may live without money and food for a while, but we definitely cant live without WiFi, Laptop and a smartphone XD . So this Instructable is all about making an All in One Portable Utility Power Bank that has an inbuilt long lasting Bluetooth music system, Lighting, Laptop charging, Phone charging, WiFi router and Modem powering system.
It only took me 3 days to start from scratch and finish it. I could learn a lot of new things during the process of making it.
Step 1: List of All Materials Required
Laminated compressed wooden slabs or plywood or hard wood, Long screws that suit the thickness of the wood
12V 7AH Battery, Hard Sponge or Thermocol, Perforated Board, Cotton, Epoxy adhesives like MSeal
Battery Indicator Circuit
470 ohm,100 ohm,68 ohm,10 ohm resistors,
4.3V, 9.1V, 10V, 11V Zener Diodes,
Led Bar Graph, Perforated Board
Automatic Battery Charging Circuit
TYN612 (SCR), TYN604 (SCR),
1N4007 Diode, 6.8V/1W Zener Diode, BR1010 Bridge Rectifier,
10k ohm Pot, 2 x (2.2k) ohm, 10k ohm, 1.5k ohm, 560 ohm, resistors,
1 Green LED, 1 Red LED,
( 15 0 15 ) / 5A Transformer
12V LED strips, Switch, White Acryllic board, Double Tape
3 x (7805), 2 x (7812) Voltage regulators,
5 x (100uF), 4 x (1uF) Capacitors,
3 x USB Female Port, 5 DC female jack,6 DC Male jacks
2 XL6009 DC-DC Boost module
4 x 3W Full Range 8ohm/4ohm Speakers,
3.5mm Female audio jack
Metallic Mesh, Cardboard
Step 2: Making of the The Box
I wanted to enclose the whole set-up in a single box.I had initially chosen plywood box with manual lamination. But the finishing was not looking the best. So went to the hardware store again and asked the guy to cut pre laminated compressed wooden board of half inch thickness to make 6*6.5*6 inch cuboid (inner cuboid).
The dimensions of the box were calculated in view with the dimensions of the 12V 7Ah exide battery, speakers, and extra clearances for other circuit components. Then all the sides were screwed to their adjacent faces using long screws with 2 along each sides.
I could have chosen hard wood to make the box. But I wanted the costs to be as low as possible with the best results. This box which I made also looks too cool and it's durability seems to be very promising.
Step 3: All the Holes of the Box
Mark all the holes that are required on the back face of the box.
On both the side faces, cut out two circular parts either manually or with the help of a carpenter of u lack the right tools. The large circular holes are to place speakers.
Step 4: Battery Level Indicator Circuit
It is very important to monitor the remaining charge that is left in the PowerBank when the battery is in its state of discharging. We could have simply used a small dc voltmeter to monitor the remaining charge left in the battery. But we have to understand that for any batter, it's discharge curve is not linear. Hence in a 12V battery, 6V does not mean that the remaining charge left is 50%. It can be less than 10%. So its better to pre calibrate our battery on our own according to our required needs. Since the charge left in the battery rapidly reduces on reaching the voltage less than 11V, so according to my circuit only one led of the LED bar graph will be lit.
This is the way i caliberated my battery
6V-11V == 1 Bar Led Glows
11V-12V == 2 Bar Leds Glow
12V-12.5V == 3 Bar Leds Glow
>12.5V == 4 Bar Leds Glow
The above results are based on the simulation results that I got from Proteus software. It's working for my battery too. So go ahead and rig up the above circuit confidently ;-)
The circuit is very easy and hardly contains 10 components, so I suggest you to better avoid a PCB to save some time and rig it up on a perforated board
The circuit diagram for the Battery Level Indicator can be found in the above images.
Step 5: Automatic Battery Charger Circuit
I didn't want to worry about the charging of the power bank all the time. If I had connected the battery to a voltage source all the time for charging, then I would have easily reduced the life of the battery since after one point of time, the battery would have charged fully and it is not recommended to overcharge any battery. So I started to search for a float / automatic battery charger and found the circuit made by electronics hub guys. I immediately rigged it up on a perforated board and found it to be working perfectly.
PostScript: This circuit was not designed by me. I sincerely thank ElectronicsHub.org for sharing and making their circuit open source.
Step 6: Lighting System
I wanted an emergency lamp too to be integrated with my power bank. I didn't wanted to buy too many LEDs and worry about their PCB's. So I bought white LED strips. Used around 2 meters (120 LEDs) for this project. I chose the front side to stick all those strips. The strips were cut in such a way that the number of LEDs in each strips were a multiple of 3 and the cutting lines were along the copper traces that were available on the strips, which were meant to be cut. Then I soldered all the terminals of the strip's anode along one side to a single wire, similarly all the cathode terminals of the strip were soldered to a single wire on the other side. In simple words, I struck and connected as many LEDs as possible on the front face of the box in parallel to each other such that they could all be lit up by a 12V DC source..
Later two holes were drilled on both the sides of the front face for sending the end wires of the LED strips into the box. These end wires were connected to a battery with a two terminal switch in series to them in the end. The back face of the box contains this switch which can be used to turn on and turn of the Lamp as and when required.
This LED Strips now created a geeky look on my power bank. :-P So I gave it a classy look by pasting an almost front face sized white acrylic sheet on top of it using double tapes.
Step 7: Placing the Speakers
On all the four large holes made in step 3, place a metallic mesh from the inside of the face. This is done to protect the diaphragm of the speakers from human contact as they are very sensitive. If they are spoilt, the clarity of the sound greatly reduces.
The metallic mesh must be insulated from the metallic part of the speaker. I achieved this insulation using a properly cut cardboard, Then I used mSeal, the strong epoxy adhesive to stick speaker to the boards. Soldering the end terminals of the speakers using multi stranded wires were done. Then all the faces of the box except the back were screwed to each other as shown in the picture.
Step 8: Bluetooth + Aux Cable Supported Music System
A portable power bank with a sound system is cool. But a portable power bank with a Bluetooth sound system is ultra cool ^_^
So I integrated a Bluetooth sound system too in my power bank. This is how I did. The circuit diagram can be found from the above images. I powered the PAM8403 amplifier boards using the output of a 7805 5V regulator. All the four speakers were connected as shown in the diagram. The polarities of the speakers don't really matter. So go ahead and connect them in which ever way you feel like. Connect everything according to the circuit diagram shown above.
I have used a 3.5mm female jack too since I wanted to play music using Bluetooth less devices like mp3 players too. So I used this component.This 3.5mm female jack helps me to automatically cut off Bluetooth connectivity to the speakers as soon as I connect a music player using an aux cable to it. This switching technique is actually an incredible logic that has been implemented on all our phone since a long time. I left the female jack open on the back side of the box to connect aux cable.I connected the bluetooth audio adapter to the female audio jack with the help of a 3.5mm male audio jack as shown in the circuit.
Step 9: Powering Circuits
I needed 2 12V outlets for powering modem and router. I also needed two 5V USB outlet for charging phone. I needed two more 5V sources to power amplifier boards and bluetooth adapter. So I achieved all the above power sources by making the connections as shown in the circuit diagram. Since the circuit is very simple, perforated boards are enough to make the connections.
For laptop charging outlet, I connected the outputs of two XL6009 DC-DC Boost circuit in parallel which had the same out put voltage of 19.5Volts. The output voltage is 19.5V because my laptop is rated at 19.5V, 4 Amps. Each XL6009 boost circuit has a max current rating of 3A. I could have bought a better rated power DC-DC step up module, but that would have increased the costs. So I connected two boosters in parallel to get 4amps. Hence the laptop charging circuit too was completed in this way.
Step 10: Final Assembly
Keep the transformer outside to make the powerbank lighter. Place all the outlets and switches in their respective holes and put mSeal adhesives from the inside after wiring them so that the outlets are not weak. After you put the mSeal, connect their respective male jacks too so that they are not oriented crossly. Keep the male jacks connected untill the mSEAL dries.Place the battery in the center, circuits in the clearance area and stuff in as much sponge/thermocol as possible in the voids so that the battery does not get even the slightest chance to move. Use as much insulation as possible by means of insulation tapes or heat shrinks and cotton.Check the outputs of all the outlets, circuits and components after connecting them to the battery and finally close the last face and screw it tightly.