# 5 seconds power supply backup for 12V 0.5A router

My country has a problem with the mains electricity supply, which cuts off and comes back straight away. My router restarts every time that happens.

What I like to know is: What would be the most efficient way to have a 5 seconds power supply backup on my router?

• Router: ASUS RT-N12+
• Power Supply:
• AC Input: 110V~240V (50~60Hz)
• DC Output: 12 V with max. 0.5 A current

A schematic would be amazing since I am totally new to this subject.

• A 12 V rechargeable battery OK with you? – winny Jun 18 '18 at 14:22
• for only 5s 12v rechargeable battery might be too much. can i use capacitor? @winny – Autobot Jun 18 '18 at 14:29
• @Autobot The problem with a capacitor is that the voltage starts to drop immediately, and that's quite a large current so you'd need to have a big(!) capacitor at higher voltage and regulate down. 12 V rechargeable is the way to go... – awjlogan Jun 18 '18 at 14:35
• Depends, are you willing to buy a ~2.5 F, 12+ V capacitor? – winny Jun 18 '18 at 14:52
• @Autobot - FYI I remember that similar questions have been asked several times over the past years. Please make sure that you have searched this site (notice the search box at the very top of this page, next to the words "StackExchange") using different combinations of words like ups, power, backup, router etc. as a previous solution may help you directly, or allow you to narrow the "solution space". For example, I remember that your suggestion to use a capacitor to "bridge" such power outages, has already been discussed (with lots of helpful calculations) in previous questions on this topic. – SamGibson Jun 18 '18 at 15:24

Rather than make something, it is probably best to by a mini-UPS such as this for about $25. It is designed specifically for keeping routers powered during power outages. Fits between the router and the router 12V power supply • is it safe to use pass-through charging power bank and use USB DC 5V to DC 12V Step up Cable Module Converter. in my country I can have both at around$15. I looked at my country sites but couldn't find any ups for the router. – Autobot Jun 18 '18 at 14:50