Li-Ion battery pack

Hi,
I have 4x PANASONIC CGR18650CG LI-ION BATTERY 2250mAh 3.7v.  I have connected them in series and it gives around 14v. My internet router is working on 12v 500mA. Is this battery pack too much for that router? I was thinking to use that battery pack as backup for my router when there is no electric power, because it's winter and every few days there are problems with power. Thanks!

Depends on how the thing regulates the input, I would play it save and use a voltage regulator or buck converter set to 12V.
Add undervoltage protection for your cells and an automatic charger and you got yourself a UPS.