Mini UPS for Routers Using One Circuit (5V-12V)

Disconnecting internet due to random power failures is a huge headache in online activities like meetings and classes. Even for one secnd of power failure router takes considerable time to restart. I made this UPS using a circuit i got from aliecpress. It is work under 12v so less power loss because 230v ups loss power when converting battery power to 230v AC supply using a transformer. I can easily get 9 hours from 4 of 2200mah bateries. It is a very easy task.

1. UPS circuit module
2. 18650 batteries
3. Battery holder
4. DC jack and adaptor (depends on your routers and power supplies)
5. Plastic housing
6. Switch
7. Wires
8. Soldering equipments

This circuit can switch power between grid power and battery power without any delay. Some circuits can work like as ups but there is a several seconds of delay. This circuit can work with 5V to 12V input voltage. You can select output voltages. So i can directly connect to the routers power supply. Other circuit can be powered from usb power source and its output voltage can be change by turining variable resistor. These circuit work with lithium and polymer based batteries. They have maximum battery capacity limits and thir charging current is not that much high so don't connect larger batteries. It has a common cathod LED indicator.

I salvaged some 18650 batteries from old laptop baterry packs. But you have to check their capacity. It is important to use batteries with same capacity. These batteries last long a good amount of time than cheap batteries that claim they have more than 3500mah. Even branded batteries like samsung, Lg, Panasonic have maximum 3500mah in there 18650 battery series. I also tested a battery that claims 4300mah and test shows that it has 1800mah and that battery died after a year. You can buy this capacity tester from aliexpress it cost me only $3. Maybe you have to buy the loading element seperately. I used a heater as the loading element. This tester measures capacity by discharging batteries energy through the loading element and calculating the amperes and voltage with time. You can set the cutoff value by pressing + and - buttons. 3.2V is the cutoff value of this circuit. Discharging current depends on the resistance of the loading element you are using. This capacity tester can measure upto 3 amps of discharging. Using V=IxR equation you can select a suitable loading element. When discharging with higher currents your results can be lower so select a discharging current that you are actually goint to use in your application. This may take several hours. Before tesing make sure battery is fully charged. After test completes screen will be blinking and shows the capacity.

Terminal are labled in the circuit board. You can find them easily. When soldering, add some solder to wires and to where you are going it to connect. It will make soldering process easier and no need to burn the circuit. I 3d printed a housing, because i had some extra materials, you can fit this into any plastic housing. I forgot to add a switch to a wire in battery connection.

You can connect it to a 12v supply and check. Mine works for more than 4 months and it works perfectly. When battery charing LED turn into red, When there is no battery LED wil; be blinking in red color , when there is no grid power and connected to load LED wil be solid blue and id no load LED will be blinking in blue. When battery is fully charged LED turn off. A one battery i used, can power the router for 2 hours and 15minutes. Hope you have a succesful build.