Which power bank is best for a WiFi router?

A regular phone power bank won't work for most home WiFi routers. Standard power banks output 5V through USB ports, but most home routers need 12V DC to operate properly. What you actually need is a mini UPS - a small battery backup built specifically for routers and other low-power DC devices. The best options in India right now are the Resonate RouterUPS Gen2 (₹), Cuzor Mini UPS, and Oakter Mini UPS, all of which provide 3-5 hours of backup for a typical 12V router and switch over instantly during power cuts. 

Why a regular power bank doesn't work for most routers?

Connecting your router to an incompatible power source can cause permanent damage, so verifying specifications is non-negotiable.

Here's the core problem. Your phone power bank outputs 5V through its USB port. Your router almost certainly needs 12V DC through a round barrel jack connector. If the power bank's voltage doesn't match the router's requirement, the router might not turn on, could disconnect frequently, or worse - get damaged.

You may try to bridge this gap with a USB-to-DC step-up cable - a cable that takes 5V from a power bank and boosts it to 12V. This works as a temporary workaround, but the switching is usually manual, meaning the moment power cuts, your internet drops until you physically connect the cable. That defeats the purpose for anyone on a video call or in the middle of a download.

Lab testing shows that over 60% of budget power bank units drop below 11.4V under a 1A load, which can trigger router reboots or DHCP failures. So even if you manage the voltage conversion, the output quality from a generic power bank simply isn't stable enough for a networking device that needs clean, consistent power. 

The right tool for this job is a mini UPS - purpose-built for routers, with automatic switchover, regulated DC output, and overcharge protection.