The power goes out, and the first thing people notice isn't the lights but the phone losing Wi-Fi. Work stops, meetings cut off, security cameras go dark.
Keeping the router running isn't expensive. But before buying anything, there's one thing worth knowing, because it determines whether the purchase is any use.
A router being on doesn't mean the internet works
Your internet connection doesn't end at the box inside your house. For fibre, there's an optical terminal on a pole or in a neighbourhood cabinet, and equipment at the provider's office. All of it needs electricity.
If the outage is only at your house, a tripped breaker, say, a battery backup works perfectly. If the outage is area-wide, some provider equipment usually has its own backup, but not always and not indefinitely.
| Type of outage | Does a backup help? |
|---|---|
| Household breaker tripped | Yes, completely |
| One housing block out | Usually yes |
| Area-wide outage, hours long | Sometimes, depending on provider backup |
| Fibre line fault | No, not a power issue |
The last row often gets confused. If the LOS light is red, the problem isn't electricity and no battery will help, explained in the guide to router indicator lights.
Calculating the power you need
The figures you need are printed on each device's adapter: voltage and current, for example 12V 1A.
Common household devices:
- ONT or modem: 12V, around 0.5–1A, roughly 6–12 watts.
- Router: 12V, around 1–2A, roughly 12–24 watts.
- Extra access point: 12V, around 0.5–1A.
- Small switch: 5V or 12V, under 10 watts.
A home with an ONT and a router needs roughly 20 to 30 watts. That's a small figure, which is why a modest battery can last a long time.
Two options, and who each suits
| DC mini UPS | Regular UPS | |
|---|---|---|
| Output | Direct current, 9V/12V | Alternating current, 220V |
| For | Routers, ONTs, cameras | Computers and other equipment |
| Runtime | 4–8 hours | 1–3 hours |
| Size | About a pencil case | About a small car battery |
| Price range | Rp 200k – 600k | Rp 700k – 2m |
| Needs a fan | No | Some do |
To simply keep the internet alive, a DC mini UPS is almost always the better choice. Routers run on direct current, so no power is wasted converting to 220V and back down again.
A regular UPS makes sense if you also want to run a computer, or if your network equipment is numerous and spread out.
Check the voltage before buying. The wrong voltage can permanently damage equipment. Mini UPS units generally offer 5V, 9V, and 12V outputs, and you need to match the original adapter exactly. Also check the connector's size and polarity.
Estimating runtime
The rough calculation: battery capacity in watt-hours divided by consumption in watts, then multiplied by about 0.8 as a loss factor.
A 10,000 mAh mini UPS at 12V is roughly 44 watt-hours. For an ONT and router drawing 25 watts, that gives about 1.4 hours. For an ONT alone drawing 10 watts, about 3.5 hours.
The figures sellers quote are usually measured at the lightest load. Expect half to two-thirds of the claim in real use.
What to watch when installing
- Prioritise the ONT. If the battery only covers one device, the ONT matters more , without it the router has no connection at all.
- Don't stack devices. A mini UPS warms up in use. Leave air around it.
- Test once a year. Deliberately cut the power and note how long it lasts. Lithium batteries lose capacity after two to three years, and you want to know before you actually need it.
- Consider a mobile backup. For extended outages, tethering from a phone is often a more reliable answer than a bigger battery.
For business premises
In a café or clinic, a power cut means the online point of sale stops and visitors lose access at the same time. Beyond a battery for network equipment, also consider a backup over a mobile link genuinely separate from the main line.
Network layout considerations for business premises are covered in the Wi-Fi for small offices guide, and the cost breakdown in the guest Wi-Fi cost guide.
Frequently asked questions
How long can a UPS keep a router running?
A DC mini UPS of around 10,000 mAh generally runs one router for four to eight hours. An ordinary computer UPS is actually shorter for this purpose, around one to three hours, because some power is lost converting current.
Why is the internet still down even though the router is on?
Because the provider's equipment outside your home, the terminal on a pole or in a neighbourhood cabinet, has also lost power. A battery backup at home only protects your side. If the outage is widespread, the network itself stops.
Is a DC mini UPS or a regular UPS better?
A DC mini UPS for the router and ONT, since both actually run on direct current and no power is wasted on conversion. A regular UPS suits you better if you also want to keep a computer or other equipment running.
