Falken 1 Mega Power Bank

Bought this to power 9V pedals and a Kraken preamp (given that the 12V output is supposed to deliver 1500mA).
To make a long story short, the Kraken preamp requires 12V with a minimum of 800mA and … it doesn’t work. The Kraken fails most of the time to power up and when it manage to stay on it’s not reliable.
I would say that it’s a good solution for pedals with a « standard » consumption but dot not rely on it for anything that requires more than 500mA like for example high voltage preamps, modelers and multi effects.