Running a DSL Router From a 12v Battery (Anti-Loadshedding DSL)

Welcome to my first instructable.

Due to "loadshedding" in South Africa, which is nothing more than a fancy term provided for controlled rolling blackouts from the national electrical provider Eskom (loadshedding status page), we find ourselves for up to 4.5 hours being 'loadshedded' sometimes even more than once per day. This gets implemented by Eskom due to power constraints on the national electric grid in the country, after Eskom has neglected to build new power plants over the last decade for the increased demand for electricity and not performing regular maintenance on the older power plants.

So a lot of people are installing solar panels and generators at their homes, but what if you live in an apartment? 200 units in the apartment complex each running a generator? Better yet if you don't have a balcony/garden were do you put the generator?

I have a UPS protecting my computer equipment and noticed that even during these blackouts my DSL provider actually stays on, but my UPS can only manage keeping the DSL router up for 40 minutes.

I did some research and decided to go the route of using an AC/DC Charger from the mains to charge a 12v battery which I will then use during the blackouts to power my DSL router which can provide me with some entertainment plus allow me to continue working (IT Engineer). The goal is to run the router on DC power straight from the 12v battery avoiding the DC -> AC -> DC conversion that would take place using an inverter in between and the losses that come with each conversion. These losses contribute to shorter run times.

Below I'll be covering how to implement this simple setup using a standard ISP rebranded D-Link DSL-2750U router that has a 12v 1A power supply with a 3.5mm DC jack.

I won't be covering any other power supply specifications and I'm not a professional electrician. I do not take any responsibility for damages or injuries occurred following this instructable.

For this instructable you'll need the following:

• 12v Battery - at least 7 Ah to 10Ah depending on desired run time (I'm using a 26Ah)
• AC/DC Charger
• Multimeter
• Soldering Iron (I'm using a basic 45w model)
• Solder
• Wire cutter & Wire stripper
• Utility knife
• RipCord (I'm using 3Amp 48v rated RipCord)
• DC Jack (I'm using a donor from another power supply due to 3.5mm being in short supply)
• Cigarette lighter plug
• Cigarette lighter socket with crocodile clips

This entire instructable was written and published from a laptop connected to my battery powered DSL router during loadshedding.

Since we are going to attempt to power our DSL router from a battery we should start by making sure that it's charged.

I'm using 10A AC to DC Multi-step charger that has: Over load protection, Output over voltage protection and Output short circuit protection.

For the battery I went with a 26Ah model, since you should never discharge these batteries beyond 50% of the capacity or else you are shorting the life of the battery, thus it gives me roughly13Ah to work with.

Depending on the size of your battery and charger this could take a couple of hours.

I'm using a cigarette lighter socket and plug for connectivity to make it easier to swap out or use other 12v devices already equipped with a cigarette plug directly from a battery. The crocodile clips also makes it easy to swap between the AC/DC charger and socket extension.

The cigarette lighter plug can be opened by unscrewing the the front tip and single screw on the body of the plug.

You should use a multimeter to measure your router's power supply to determine the polarity of the DC jack. My model has a negative barrel (exterior) with a positive center(interior) -(+)-

So on one end of a piece of RipCord, about a 1 metre should do, solder on your DC Jack and on the opposite end solder on the cathode(-) and anode(+) of the cigarette lighter plug.

Your cigarette lighter plug might come with a LED and resistor to serve as an indicator, it that case the long leg of the LED goes to the anode with the short to the resistor and from the resistor to the cathode.

Remove the charger from the battery.

Connect the crocodile clips to the battery, e.g. red to positive and black to negative.

These days everything is color coded in one form or another if the crocodile clips are not color coded look at the wires, positive usually gets marked with a white line and the terminals on the battery have indicators on the casing.

If there are no clear markings use your multimeter instead to determine which is the correct ones

Once you've plugged in the cigarette lighter plug into the socket use your multimeter to confirm that the polarity is correct.

The voltage reading should be about 12.8v on a fully charged battery.

The moment of truth.

Plug the DC jack into the router and turn it on, and in about 2 minutes (depending on the boot and authentication times) you should be online using a 12v battery.

Thanks for reading.