A mini UPS for your router is one of the cheapest ways to make load shedding tolerable. But the capacity numbers on the box are easy to misread, and people routinely buy something too small. Here is how to work out what you need in about two minutes.
Step one: add up what you are powering
Most South African homes need two things running: the fibre ONT (the box the fibre line plugs into) and the WiFi router. Typical draw:
- Fibre ONT: roughly 5 to 8 watts
- WiFi router: roughly 8 to 12 watts
- Small network switch, if you have one: roughly 5 watts
So a normal setup draws somewhere between 13 and 25 watts. Call it 20W for planning.
Step two: convert the UPS rating
Mini UPS units are usually sold in mAh at a stated voltage. To get watt-hours, multiply amp-hours by volts.
A 12000mAh unit at 12V is 12 Ah x 12 V = 144 watt-hours on paper.
Then discount it. Real-world conversion losses and the fact that you should not fully drain a battery mean you plan on roughly 70 to 80 percent of the paper figure. So call it 100 to 115 usable watt-hours.
Step three: divide
115 watt-hours divided by 20 watts is about 5 to 6 hours of internet.
South African load shedding stages are typically 2 to 4 hour blocks, so a 12000mAh unit comfortably covers a single stage and usually two in a day, provided it gets time to recharge between them.
The mistake people make
The recharge window matters as much as the capacity. If you are being shed twice a day with only a few hours between, a unit that takes six hours to recharge will not be full when the second block starts. Check the recharge time, not just the capacity.
What about the TV or a laptop?
Do not put them on a router UPS. A laptop charger alone can draw 45 to 65 watts, which would flatten the same unit in under two hours. Laptops have their own batteries; keep the mini UPS for the network gear that does not.
Rough guide
- Router only, one stage: 8000mAh is enough
- Router plus ONT, two stages a day: 12000mAh is the sensible pick
- Router, ONT, switch and a camera: step up to a larger unit or a small inverter
Our load shedding range includes a 12000mAh mini UPS sized for exactly this job, along with solar lighting and power banks.