Plenty of people use power banks to run their smartphones and tablets for longer. Looking for a steampunk version? DemonCrafts is offering them on Etsy. This Steampunk Power Bank has 10,000 mAh capacity, so it can charge your phone up to 3 times (depending on the model).
The power bank has 4 LED power indicators. It can be charged via Micro USB. These are handmade and unique. More information is available here.