Update: 24 October 2022
1. Added a 15V outboard power supply to use when power is available. This resulted in a far better charge voltage for the battery pack.
2. Added a direct coupling wire from the input of the unit to the two buck converters. In other words I bypassed the battery charging process. This eased the load on the input XL4015. If there is a power outage it still switches to the battery as per original diagram.
3. Swop the LM2577 LM2596S step up/down converter board for a XL6019 step up converter board. I found that the XL6019 does a far better job than the original suggested up/down converter and does not create a lot of heat.
This UPS has been in operation for several days now. I am
very happy with the performance of the Internet Router UPS. So far it
is working as I would like it to work for my setup. I am currently contemplating to make further changes to the unit. Whether this will materialize needs to be seen as there is an old saying - "Do not scratch in a project that is working well, just now it might not work at all!!"
Original Posting:
The ever worsening of load shedding in South Africa and the work-from-home policy for business continuity resulted in the DIY Internet Router UPS Project. Working from home means your home's WiFi networks are more important than ever especially during periods of load shedding. Anyone with a fiber-line connection will know that their Internet connection drops whenever the power goes out. It is annoying if you are in an important meeting/webinar or just browsing the Internet and there is an interruption due to load shedding. I was approached by my wife and son to solve the issue of fiber Internet going offline during periods of load shedding. Now I hear you think that this is easy just use a power inverter connected to a battery during these periods. Yes that is one option but why should I run a power inverter just for an item that draws less than 2 amps. My Amateur Radio Shack runs fully from Solar Power and and an inverter. I do not have any problems running my computer, radios, Shack Router, 3D printer, GRHub Network etc, etc. from this system. Unfortunately the Shack is located quite a distance from the Fiber Connection Point and Home Router and running wires from point to point is not desirable nor the answer.
I had two options:
1. Using a conventional UPS ( Bulky and Costly )
2. Mini-UPS ( Light and Cheap )
You guessed correctly I went for the Mini-UPS. Now I know you can buy these from various outlets but at a costly price as it seems that load shedding is now the excuse to "milk the cow" and to make money out those not technically skilled. Well I am definitely not going to "be milked" so I choose the DIY Route by constructing a Mini UPS for the house Router and Fiber Internet Connection. Google is your friend as you can find a variety of UPS projects that will serve your needs.
Before I continue I must confess! This is the most ugly constructed project I has ever build during my long "career" in amateur radio. However it works great and the reason for the ugly construction is that I needed the unit ASAP and there was no time to 3D print a nice looking cabinet for the project. Ordering an ABS case was also not a option. I needed the project as in yesterday. Once I have some time on hand I will print a 3D cabinet and re-fit all the components into it. This could easily take anything from three months to three years. Hi Hi!!
I am not going to go into full detail as this unit is available on many sites with full instructions and photos. I did however changed the circuitry to my liking and needs. Here are the features of the unit that I constructed:
1. Automatic Switching ( using a Bridge Rectifier ) between the power supply
and battery pack during a power outage. More info on using the the bridge to do the switching can be found HERE.
2. Two Output Ports:
12V / 3A and 5V / 3A (Voltage and Amps can be changed by turning the pots on the modules)
3. 8 hours of backup time
4. Battery pack with 3S BMS in a 3S2P ( 3-series and 2 parallel ) configuration
5. Additional Protection via 1N5821 Diodes
6. Additional Filtering via 1000uF /16v electrolytic capacitors on the input and output terminals
Finally: I enjoyed constructing this project. It is currently on test and I will update this post once I am happy that the unit functions as it should. Provisional tests were successful, however I would like to see what it will do with stage 4 or 6 load shedding.
Images: (Click on images for larger view.)
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Update 20 October 2022:
