I was thinking to buy this one:
MAXOAK 50000mAh 185wh 6 Port(5/12/20v) Portable Charger External Battery Power Bank
https://www.amazon.com/gp/B00YP823NA
But I saw one review for the battery as below:
I purchased 3 of these to use as a power source for a 12 volt wireless camera. Initially everything seemed perfect, the device even came with a connector that worked beautifully with our camera out of the box! Then the camera shut down 15 seconds later.... Turns out that there is a minimum current draw required to keep this device on otherwise it shuts down. I connected 2 wireless camera's, and still not enough current. Added a USB LED light, still not enough current.
If the main purpose is to charge a cellphone, or laptop then I'm sure this would be a great device. Otherwise, you might want to look elsewhere for a battery to power your low wattage devices.
This is a true shame as due to the large capacity of this device, it would be a great power source for low powered applications such as mine. Would power that camera for days if my calculations are correct.
I don't know how much true it is through!