Just bought an external dc 12hrs battery power pack for powering up my laptop (toshiba satelitte l645d). Ever since then my laptop has been misbehaving.

Using the laptop directly connected to the external battery leads to a periodic loss in power, which happens when I open more applications or plug my phone to the usb port of my laptop.

Kindly need help as I don't know whether its the laptop or the battery.

P.s. The laptop has no internal battery, works well when powered by electricity, ..also any information about the external dc battery would be appreciated.