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PC/Laptop Uninterruptible Modem Backup Power Supply

Why do I need a modem backup power supply which is uninterruptable? How do I fix the problem? Well the answer is to have:

1. A reliable AC mains to 12V DC power supply which not only powers your modem in a regular way BUT when there is an AC mains outage, it will instantly switch over to your backup battery.


2. Your 12V SLA backup battery [your choice of type] with sufficient capacity to power your modem for as long as you like - perhaps to the extent of your laptop power supply.

Well for quite some time now Australia has been switching over from ADSL to a limited system using optic fibre cable called NBN. I won't discuss the NBN here. For reasons which I will explain later I need a landline telephone, unfortunately the NBN phone is VOIP which means in a power failure [blackout] your telephone is gone - no phone. However, with my "PC Uninterruptible Modem Backup Power Supply" - see photo below - my telephone continues to operate.

Several years back my locality suffered quite a severe mini cyclone [hurricane] which among many other things left us without power for about a week. This was the old landline ADSL days and of course I still had a telephone service - fortunately. I say fortunately because nearby neighbours did not have landline phones, being younger ones they relied entirely upon Wi-Fi from their smartphones. We had a medical emergency, and there was no Wi-Fi because nearby phone tower backup batteries were exhausted and down - not so our local telephone exchange.

I was able to call paramedics on my landline telephone and a potential tragedy was averted. For days before that, all those folks with their "Smartphones" - their umbilical cord to life - had to travel to a nearby Club which was offering emergency phone charging facilities. They had years earlier installed a powerful backup generator on the premises. However to make mobile phone calls you had to travel several kilometres away to find an operating mobile [cell] phone tower.

Under those circumstances, how would you like to suffer a heart attack, as just one emergency without access to a phone?

When I switched over not so long ago to the much vaunted NBN [National Broadband Network] I was shocked to learn that like so many areas I would only be given FTTN [Fibre to the Node]. That means I still use my underground copper phone lines back to a Fibre Optic node somewhere. It's up the street, around the corner and about 500+ metres away. O.K. I derived some speed benefit of about twice my ADSL speed to something like 38 Mbps. I don't care about the speed as I don't sit around watching films online.

The biggest shock of all was no landline phone. I could retain my phone number but it was VOIP and in a blackout? Tough luck... wait until power is restored. Phone coverage for my Samsung Galaxy 4? Sometimes it's a terrific 4G - provided I leave my well insulated [alfoil] house, walk down to the front footpath, and then sometimes walk a few houses up the hill. I live in a variable RF [radio frequency] black hole, well a hollow to be more precise.

Want to be suffering a heart attack all by yourself during a blackout in those circumstances? Well as one happy chappy who owes his life to four paramedics when suffering a heart attack a few years back I can assure you I am very much attuned to the poweful need for a "PC Uninterruptible Modem Backup Power Supply". Yep you can go out and buy all kinds of Uninterruptable Backup Power Supplies of all sizes, and of course all different prices. What surprised me was there do not seem to be any around to cater for just your modem only.

Telstra, once Australia's only phone company, and still having vast numbers of folks who only have landline phones [not interested in the internet or smartphones] offers their such customers an Uninterruptable Backup VOIP Power Supply. No, I don't have any details on it, I gave Telstra away many years back.

This led to my quest. Here I must emphasise that my solution is "what suited me, with my technical knowledge and skills, along with my personal retirement income budget". Your personal requirements, skills, and budget may of course be vastly different.

Figure 1 - My PC Uninterruptible Modem Backup Power Supply alongside modem - yes I will box it

For the backup in the inelegant photo you see above there are only two major components, and three set of wires I had to set up. At the time of writing [30th June, 2018] the total cost for me was only those two major components. The backup battery I purchased on eBay from Lanplus, it was a 12v 7.2ah UPS SLA AGM Sealed Lead Acid Battery and it cost me a whole $A 20.95 including freight from Heidelberg West VIC 3081 to the Central Coast of NSW.

Consider this little gem of a fact, no matter where you buy such a battery [not in person] from - the freight for a 2 Kg parcel in a well protected box measuring [approx] 110 mm wide X 140 mm high X 200 mm long will be how much? Just checked, AusPost quote online between the two post codes is $A 13.80

Think about it? My nearest outlet to buy in person would likely be Jaycar on the NSW Central Coast - they're 25+ Km away from me and for a similar Jaycar priced 12V 7.2Ah SLA Battery they want $34.95

Now with the UPS charger I kept going back to Amazon, and in particular various Drok models for a variety of different reasons. Eventually I settled on this Drok model from Amazon.

This DROK 110V 220V UPS Battery Backup Uninterruptible Switching Power Supply from Amazon USA cost me a few weeks back $A 35.11 plus $A 12.55 shipping a total of $A 47.66. The price in the USA was around $US 25.00 plus freight [$US 9.18 to Oz]. With bank charges it ended up costing me just under $A 50.00 - disclosure - this is an affiliate link of mine going to Amazon.

DROK 110V 220V UPS Battery Backup Uninterruptible Switching Power Supply 12V 120W 110V-240V to 13.5V DC 50/60Hz with Battery Interface for Charging - Model #4310 supplied by Drok.

An extremely basic data sheet http://www.cs.droking.com/wp-content/uploads/2016/06/DATASHEET_090947.pdf

My total costs? Around $A 70.00 all up. AC power and 12V DC power cables came from my prolific junque boxes.

Of course even during a relatively short blackout the modem backup is not going to power my custom built PC with its seven assorted hard drives, BUT the modem does continue to provide Wi-Fi for my Laptop for which I can conserve battery power by only downloading essentials like business email briefly every so often. I even keep a spare charged up battery for the laptop so I'm not entirely cut off from the world.

I have no connection with the eBay battery supplier LanPlus beyond being a very satisfied cutomer. Their site is https://www.lanplus.com.au/.

Wiring up diagram - there is a green three pin connector block on the left side for 110/240V AC Earth, AC Neutral/Return, and then AC Active/Live. There is between the fuse and the four output pin block a white 4 pin JST type connector. I am informed the two centre pins are DC ground for LEDS. Outer pins are designed for a Green LED, and the other one for a Red LED [you choose your own colours].

The official response to a question I asked about them was: "These 4 pins are for connecting two LED indicators. One is used for indicating that the mains supply is on. The other one is a low voltage indicator for reminding that the voltage of the backup battery is lower than 10V when the battery is discharging. Other green connector blocks.

Figure 2 - My PC Uninterruptible Modem Backup Power Supply wiring diagram

Figure 3 - The Drok model #4310 Backup Power Supply Edge Power Connectors

DROK Storefront

A rather interesting and extensive range of Drok products sold through Amazon, I was predominantly interested in their DROK UPS Backup Uninterruptible Power Supply for a backup to the VOIP Modem though. As always, worth a look around, costs nothing.

Go to the Amazon DROK Storefront