Preface: As I was looking for a link to my Anker I discovered it us 2.4A
per port for a total of 4.8A
https://images-na.ssl-images-amazon.com/images/I/61-CJpIPpPL._SL1500_.jpg
My Anker has powered 2 cams reliably though I normally use it for one. The usual recommendation for one cam is 1.5A, yet the actual current drawn is usually well under 1A. Part of the reason for the disparity is safety: Better to not run the PS at it's full output or overdraw from it. Another part is that many of the lesser PS's are over-rated and will not deliver what they are advertised at; Most which are rated 1.5A or more have been shown to support a cam reliably.
You absolutely need a solid and dependable power source just as you absolutely need a high quality recommended SD card; half of the problems reported with dashcams are traced to these two places. Going cheap here isn't worth the risk of not having the recording you need when things go wrong
Phil