A traditional UPS is quite bulky, inefficient, and expensive. I.e. using lead acid batteries, converting that stored charge to AC, and providing large AC sockets, made traditional UPS devices not often used.
In contrast a Lithium-ion (polymer) UPS, providing DC outputs only,
is much less bulky, more efficient, cheaper, and more generally useful.
In the application described below, I use a "mini" UPS to keep
my internet router and ONT available in the presence
of power outages, whether external, or due to inadvertent unplugging etc.
Powering the internet access devices
The main functionality I was after was to power my internet router and ONT. There were various options available on amazon, though on the UK site most were only available to deliver 2A on the 12V DC output, whereas I needed at least 3.5A (45W) to replace my 2.5A and 1.0A power supplies on the router and ONT. aliexpress has any combination of these devices available, and I went with a 60W 20800mAh LiFePo4 DC UPS for €120 including shipping, which took 2 weeks to ship from China to Ireland.This Mini UPS provides the following functionality:
- Replacing 2 PSUs (wall warts), with a neater single standard a/c plug
- Uninterrupted power on power cut or inadvertent unplugging
- Local USB charging (for phones etc.)
- Accurate / Responsive power meter through the LCD display
- Remote power delivered over Ethernet (PoE)
Note the device I went with had multiple DC outputs, but one may suffice where the combined power draw is within the max current rating. I.e. one can use a DC splitter cable to power multiple devices (at the same voltage) from a single port. One such splitter cable was supplied with the UPS, which I used to minimise the cabling involved. Note it's inadvisable do the opposite and drive a single device from multiple DC ports, as one of the ports would be favoured due to slight resistance differences, and tend to burn out more quickly.
Distributing the power over Ethernet
This aspect is less general, but was useful to me to also distribute power to my remote office. Since I had Ethernet already routed from the router to my office, it made sense to use the PoE functionality to provide power to this separate location depicted in the diagram above. Ethernet is generally easier to route than DC, so PoE is very useful to simplify cabling to remote locations. In my case I used flat Ethernet cable which was very easy to route, and fit at the edge of carpet for example. I bought two devices to leverage PoE in the office:Tenda PoE powered 5 port gigabit switch for €25, This powered ethernet switch will allow multiple wired laptops to continue with uninterrupted networking. Now often one can continue with wireless to the router, but this is not always sufficient at the remote location, and there will always be some issues in a switch over to wireless. For a single laptop though, a switch would not be needed, as it could connect directly to the router.
REVODATA Gigabit Type C PoE Splitter with 5V 2.4A output for €15 euros. A separate USB output is always useful, and can power a phone or augment the power provided to a laptop. In the laptop case with multiple connected USB power, they generally take power from the highest powered cable attached, and so will fall back to this 10W option in a power cut. All Apple laptops support this mode of operation at least.