DC UPS FAQs: What Buyers Need To Know About Router, CCTV And Network Backup Power

When the power goes out, low-power devices such as routers, ONU/ONTs, CCTV cameras and wireless APs may lose power immediately, causing Wi-Fi interruptions, network downtime or security monitoring failures.

So, what problems can a DC UPS solve? How long can it run your devices? And how do you choose the right one?

The following 10 FAQs answer the most common questions about using a DC UPS during power outages.

1. Why Does Wi-Fi Stop Working During a Power Outage?

Because the router and ONU/ONT also need continuous power.

Even if your smartphone or laptop still has battery power, the internet connection may stop working if the router or ONU loses power.

A DC UPS can continue supplying backup power to compatible network devices when the main power fails, helping keep Wi-Fi and network connectivity available.

However, if the ISP's network line or upstream network itself experiences an outage, a DC UPS cannot restore the internet connection.

2. What Devices Can a DC UPS Power?

A DC UPS is mainly designed for low-power DC devices, such as:

• Routers

• ONU/ONTs

• CCTV cameras

• Wireless APs

• Optical network terminals

• Some network switches

• Other compatible DC devices

Before connecting a device, make sure its input voltage, power consumption, connector and polarity are compatible with the DC UPS.

3. How Do I Know If a DC UPS Is Suitable for My Router?

First, check the input specifications on the router's power adapter.

For example:

12V × 1A = 12W

If the DC UPS supports 12V output and has a maximum output power higher than 12W, and the connector and polarity are compatible, it can meet the router's basic power requirements.

Therefore, choosing a DC UPS is not only about battery capacity. You also need to check the output voltage and maximum output power.

4. Can a DC UPS Power a Router and ONU at the Same Time?

Yes, but you need to calculate the total power consumption of both devices.

For example:

• Router: 12W

• ONU: 6W

Total power consumption:

12W + 6W = 18W

If the DC UPS has a maximum output power of 18W, the combined load has already reached its rated output limit. In practical applications, it is generally better to choose a model with some additional power capacity.

You also need to make sure that the required output voltage and connectors are compatible with both devices.

5. Can a DC UPS Power CCTV Cameras?

Yes, but the appropriate DC UPS should be selected according to the camera's power supply requirements.

For example:

• 12V CCTV camera → Choose a DC UPS with compatible 12V output

• PoE camera → Choose a DC UPS that supports the required PoE output

If multiple cameras are connected, you also need to calculate their total power consumption.

For example, if two cameras each consume 8W:

8W × 2 = 16W

The maximum output power of the UPS should therefore be sufficient to support at least a 16W load.

6. How Long Can a DC UPS Run a Router?

Runtime mainly depends on battery energy, device power consumption and system efficiency.

You can use the following formula for a basic estimate:

Estimated Runtime ≈ Battery Energy (Wh) × Efficiency ÷ Device Power (W)

For example, suppose a DC UPS has a battery energy of 38.48Wh and an estimated efficiency of 90%.

For a 12W router:

38.48 × 90% ÷ 12 ≈ 2.9 hours

For a 24W device:

38.48 × 90% ÷ 24 ≈ 1.4 hours

Actual runtime may vary depending on battery condition, temperature, load fluctuations and system efficiency.

7. How Do I Calculate the Battery Capacity I Need?

You can estimate the required battery energy based on the device's power consumption and the desired backup time.

For example, if a device consumes:

12W

and you want it to run for:

4 hours

The theoretical energy requirement is:

12W × 4h = 48Wh

If the system efficiency is assumed to be 90%:

48Wh ÷ 90% ≈ 53.3Wh

Therefore, when choosing a DC UPS, battery capacity should be determined based on the actual load and required backup time, rather than simply choosing the highest mAh rating.

8. Does a Higher mAh Rating Always Mean Longer DC UPS Runtime?

Not necessarily.

mAh is one way of expressing battery capacity, but batteries with different voltages can store different amounts of energy even if they have the same mAh rating.

A more direct calculation is:

Wh = Voltage (V) × Capacity (Ah)

For example:

7.4V × 5.2Ah = 38.48Wh

Therefore, when comparing different DC UPS systems, it is better to consider:

Wh + Device Power Consumption + System Efficiency

rather than comparing mAh alone.

9. What Is the Difference Between a DC UPS and an AC UPS?

The main difference is their output type and the equipment they are designed to power.

If your main goal is to keep routers, ONU/ONTs or CCTV cameras running, a DC UPS is usually a more direct solution.

If you need backup power for computers, servers or other AC-powered equipment, an AC UPS is generally more suitable.

10. What Should I Look for When Choosing a DC UPS?

You can select a suitable DC UPS by checking the following specifications:

① Output Voltage

Make sure the output voltage matches your device, such as 5V, 9V, 12V, 15V or 24V.

② Maximum Output Power

Make sure the UPS can support the actual power consumption of your device.

For example, if the device requires 12W, the UPS maximum output power should not be lower than 12W.

③ Battery Energy

Pay attention to the battery's Wh rating and calculate whether it can meet your required backup time.

④ Output Connectors

Make sure the available DC, USB, Type-C or PoE outputs are compatible with your devices.

⑤ Total Power Consumption for Multiple Devices

If you plan to connect multiple devices, calculate their combined power consumption before choosing the UPS.

Final Summary

A DC UPS is mainly designed to solve one practical problem:

Keeping routers, ONU/ONTs, CCTV cameras and other low-power DC devices running when the main power goes out.

When choosing a DC UPS, don't focus only on battery capacity. You should also check:

Is the voltage compatible? Is the output power sufficient? Is the connector suitable? Can the battery Wh capacity provide the required backup time?

When these specifications are properly matched, a DC UPS can provide a practical backup power solution for keeping network and security devices operating during power outages.