If you are going to buy a UPS only for your modem or wireless router, read this.
Most of the UPS require a minimum load to function properly. If we dont give a minimum load, the UPS will turn off after 5 to 6 minitues.
Usually the minimum load is around 50W. And modems and wireless routers consume only around 5 to 8W. So if you connect only a modem or router, you wont get huge backup time.
Recently i bought an iBall UPS for my wireless router. The router is of around 7W. And i am getting a backup time of 5 minutes. After 5 minutes, it will switch off and internet is disconnected. So i need to restart it again to get 5 more minutes. And nothing was specified in iBall UPS’s manual.
So, before buying a UPS for your modem, ask the dealer specifically whether the UPS supports low watt devices. Some shop owners sell modified UPS which will work with low watt devices and gives more than two hours backup time.
Update: After fighting for half an hour with the shop keeper, I exchange the iBall UPS with APC BR600CI-IN UPS by paying 550 Rs extra. And APC UPS gives better backup time for my wireless DSL router.