for my final project for tech class in school i decided i wanted to make a power bank that has a full 120 volt outlet rather than just usb ports. depending on what you substatute as well as what you already have your price may vary but this project came to a total of $171 for me. (yes spending that much on a school project is dumb but it was fun so it was worth it)
Step 1: The Outlets
I decided i wanted each outlet to have its own switch so the "neutral" side of the switch remained connected but the "live" side was separated. depending on the outlet you use it might be easier to separate but as you can probably see i had to cut a little bit of the plastic away to get my tools in to disconnect it. thankfully it doesn't matter if you cut that bit of plastic as it is hidden under the plastic of the enclosure.
Step 2: The Wiring for the Switches
the wiring for the switches is pretty simple. the "ground" and "neutral" wires connect directly to the outlet but the "live" wire goes to the "main switch" which is the switch that turns both outlets on and off. then i have two wires coming off of the "main switch" and each of the wires go to their own secondary switch. this way i can have just one outlet on or both outlets on.
Step 3: The Batteries
Originally i was going to have sets of 4 18650 cells in series parallel but quickly discovered that would not be suitable for me. instead i got a couple of small 12v batteries and connected them in parallel so it's still 12v to the inverter but double the capacity of just one battery.
Step 4: Charging
for charging i was just going to use a plug in charger but then i went to Canadian Tire with my dad where i found a solar panel trickle charger for 12v batteries which uses the same quick connect plug as the plug in charger. one quick connect wire is just hanging out through a hole in the back but i regret doing it this way in the end because not only do i now have an unnecessary hole in my box but i always have to be careful of how i put the box down or how i store it so i don't break the cord as that could cause a short circuit which could cause a fire. more on that later.
Step 5: The Inverter
for this project i just used a 120 watt inverter i bought at Walmart for $17. well it can't power too much it works for powering lamps and even my gaming laptop which is all i need at the time of creating this.
Step 6: WARNINGS
while doing this project i nearly started an electrical fire more than once as the 12v batteries are capable of 8 amps output so be very careful with wiring. i know everyone always says it but ALWAYS DOUBLE CHECK YOUR CONNECTIONS AND WIRING WITH A MULTI METER. i attempted to connect a switch which lights up when in the "on" position and ended up with a dead short across one of the batteries which nearly caused a fire, melted the wires, and killed the light-up switch.