Introduction: Steam Punk Your UPS to Get Hours of Uptime for Your Wi-fi Router

About: Software developer, pilot, musician, squash player and general hobbyist with an interest in the MAKER community..

There is something fundamentally disagreeable about having your UPS convert its 12V DC battery power into 220V AC power so that the transformers running your router and fibre ONT can convert it back into 12V DC!

You're also up against the [typically] 15%-20% efficiency loss of your modified sine wave inverter, as well as the reality that a UPS is there to give you an opportunity to power down rather than to run your peripheral devices for an extended period of time.

So how do we beat those numbers??

One way is to simply bypass the inverter and run power directly from the battery - that is what we're going to do in this Instructable.

We will:

  • provide three panel-mounted 12V inputs
  • display the current voltage of the battery via a small meter
  • add a knob to control the volume of the alarm
  • put everything into a little carry case

Most importantly, we will be adding some blue bling and having a bunch of fun!!

There are basically three major steps, viz:

  • build the box that houses the controls for the voltage display, volume and power outputs
  • wire everything together
  • finish it off with a carry stand

Let's get going...


Step 1: Build the Bling Box

Boxes for projects are expensive [R75 for a correctly-sized box in this instance] which is what provided the impetus to add the bling element - I did not want to pay that much for a box so had to find a DIY solution!

I ended up getting a super cheap Major Tech enclosure from Mica Hardware, for R9. I could have bought a standard cover to fit this enclosure but they were approximately R24 each. Since I already had some Perspex in the workshop, I decided to build my own cover which at the same time, provided visual access to the inner workings.

It's a 100mmx100mm enclosure so I first cut the Perspex to size [Dremel with a cutting disc] and then rounded the corners to fit the box [Dremel with a sanding disc]. I drilled the mounting holes and fixed the cover with standard electric-enclosure screws - they are too long for this purpose but they ended up adding to the industrial look.

To provide the bling effect, I mounted two blue LEDs at the bottom of the enclosure and covered it with another piece of Perspex which I had sanded to reduce it's transparency. This allows the blue light to be diffused around the box instead of appearing as two "point" light sources.

Blue LEDs have a 3.2V forward voltage and I wired them in series, which meant I only needed a 250 ohm resistor to drive them with the 12V battery from the UPS.

Each LED was mounted via a 5mm hole drilled in a piece of EGA trunking, cut to the correct length. EGA trunking is a good solution for building mountings as they have multiple sides for fixing and can be easily shaped. These ones were trimmed along the one long edge to cater for the curve at the bottom of the enclosure and then fixed to each side using a #3 20mm self-tapping screw. The scuffed cover plate had 4 holes drilled in it and it was then mounted on the the EGA trunking "rails" using another 4 self-tapping screws.

Appropriate slots and holes were cut into the top cover plate to house the voltmeter, the rotary knob and the 3 sets of positive/negative power points.

Step 2: Wire It All Up

I wanted to provide three separate 12V power lines to ensure they were never overloaded and that a failure on one of the lines did not affect the other lines. This made the build a little more difficult so you will need to decide what mileage you want to get out of this step.

I used piggy-back connectors to connect the power lines to the battery in the UPS. However, I also needed a power line to run the LEDs and one to carry the voltage to the voltmeter. This meant I would need to connect SIX wires to each battery terminal, which is a lot.

I compromised by adding a single set of connectors for the power lines and feeding them to a connector block, which I then wired to act like a breakout board. This does mean there is a single point of failure as far as the power lines go but the wires are thick gauge and the connector block is sturdily wired.

The connector block was popped into an available cavity behind the front panel of the UPS with the two supply wires routed along the sides of the case. The construction of your UPS will dictate how you route your cables.

The three sets of cables on each battery terminal and the connector block can be seen in the pictures.

To add in the rotary volume knob, you will need to locate the piezoelectric speaker in the UPS and unsolder one of the legs from the back of the circuit board. Solder a piece of wire into the now vacant hole in the circuit board and solder another wire to the now free leg of the speaker. Strengthen using heat shrink and route the wires along a similar trail as the power lines.

Finally, another set of piggy-back connectors was used to run a power line for the voltage meter and the LEDs. Route similarly.

Step 3: Mount It in a Carry Case

The carry case was made from material from a wooden bench I made 10 years ago and which I recently reduced in length to fit another part of my house. The recycled nature of the material fitted in well with the industrial feel of the project.

The carry case consists of a base which is kept 10mm above the floor by legs. A shelf was added to hold the Bling Box and a Plug Box housing the two 15A plugs that originally powered the transformers for the router/ONT.

The legs have a dowel rod mounted between them at the top to serve as carrying handles. This is a standard bit of carpentry so not much to explain here.

The power cables and volume control wires are routed out of the UPS via a modified cooling slot [see image]. The main power cables are then routed to the posts mounted in the Bing Box while the power line for the voltmeter/LEDs and the volume wires are routed underneath the shelf.

These wires are fixed to the ends of the bolts you see in the front of the shelf, effectively routing the cables to the top side of the shelf where they can be joined to the voltmeter/LED power requirements [red & black cables] and the volume wires [red and blue].

The ends of all of these cables are fitted with 3.2mm eye lugs, crimped and soldered in place - this makes it easy to connect them using #3 bolts. Everything is strengthened/finished off using layers of heat shrink and cable ties.

Finally, the Bling Box and the Plug Box were fixed to the top shelf using 20mm cross-cut screws.

Step 4: What Would I Do Differently Next Time?

This project took longer than anticipated because although I am a meticulous planner, there were a couple of things that caught me by surprise. These are the main things I would do differently.

  1. Use thinner wire for the 3 power lines
    The 2.5mm wire I used is overkill and it's difficult to fold and bend into the tight spaces and corners of the UPS and the Bling Box. I would definitely drop down to 1.5mm wire.
  2. Separate the wires from the UPS
    It was a constant struggle to wire everything up and fit it on to the carry case with the only slack being provided by the length of the power cables. I would definitely find a way to mount some sort of a connector in the UPS case that allowed the Bling Box to be completely removed from the UPS when it needed 'editing'. I cringe at the thought of replacing the battery.