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We bought an Asus router n66U to be installed in a tourist bus along with a server. The bus has a inverter to supply a 220V AC. However, there can be abrupt power fluctuations specially during ignition start. We need to ensure that our server and router run without disruption even during minor power outages.

We were brainstorming on how to solve this in a cost effective manner and came up with an idea that we can use a second hand laptop as our server. It has a battery installed and a charger to charge it. We could remove the display from the laptop to reduce weight and size of the unit.

Laptop for server sounded good. But we still have the problem of supplying uninterrupted power to the router. We could take out power from the battery and supply to router directly. But that could be challenge since AFAIK, the battery in laptops provide 12V and 5V output and our router requires 19V DC input.

We could also use PoE injectors like this. A PoE injector seems a good solution, but I'm not sure it's reliable. Will it damage the router, or is a better way to do this?

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I second MadHatter's suggestion of using a desktop UPS. In fact, that's exactly the solution I settled on a few years back when I got a contract to set up wireless coverage for a couple million square feet of warehouse. To avoid needing expensive new fiber runs, the routers and switches for each building were hung up in the ceiling, and provided power with a small UPS usually used to power a single workstation. Worked flawlessly.

  • I also question the utility of trying to supply power to a device that's undervoltage and on an interface on which the device isn't built to accept it. – MadHatter supports Monica Feb 24 '15 at 9:01
  • Hmm interesting, what is the rating of UPS should I buy to power a CPU (Not high computing) and a router? – Kartik Feb 24 '15 at 9:21
  • @Kartik Just make sure it's rated for the combined power needs of your server and your router, which probably won't be hard. (Wattage rating of the UPS needs to be greater than or equal to the wattage demands of the server and router.) As to capacity, you just need to decide how battery run time much is enough. For my project, they were big on saving money, so we ended up with low capacity models, and about 5 minutes of run time on battery power. If you don't need extra battery capacity, don't pay for it. Smaller batteries are also significantly lighter, so that's another thing to consider. – HopelessN00b Feb 24 '15 at 9:26
  • Thanks. We need power backup of few minutes as well. We just have to make sure server and router do not restart when the bus starts. Power fluctuates for a few seconds. So i need an UPS with power output more than sum of the two and a battery as small as possible – Kartik Feb 24 '15 at 9:31

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