Ah. the product description here doesn't explicitly mention this feature, that power input will automatically switch to source against the battery.
Damn. I would have put this board in on my last order had I understood that.
I read the datasheet best I could, and I thought "prioritized" must mean that "load" port gets 100% of DC IN when needed.
But that's not the whole store... if DC in shuts down, power source will automatically switch to the battery.
That's pretty sweet! It's a charger -and- a power supply.