I like those timelapse, by the way if you have USB powered IP Cameras I found an USB Power transformer 5V/2.1A but with integrated 2 x 18650 batteries that make this power transformer act like an UPS in case of power failure 
I also found other product like this one (5V but also 12V for Routers, NAS and usual IP Cameras…) but that plug between a power tranformer (5.5 jack connector) and the powered device, they also use 18650 batteries so easy to change or to buy may be more powerfull one like 3500mAh NCR from Panasonic (I guess they do provide only 2000~2500mAh 18650 batteries)
