The docs state that it chooses DC over USB when both are connected, but doesn’t mention what it chooses if both DC and LiPo battery are connected. From my tests, it seems to choose the LiPo battery.
To me, this seems backwards; as in a normal scenario if powering by DC you would have a small LiPo battery connected as a backup if the DC ever drops out (or if your DC is a large battery pack and goes dead you could swap it out without disruption). Can anyone shed any light on this please?
The PMIC on the power shield (BQ24030) dynamically switches between the input (USB or DC) and the LiPo to power the system load. It will choose the DC source by default, but once the system voltage drops under heavy load, it switches over to the LiPo. Is there anything in particular you a powering from the shield, and what is the DC source spec?
So from what you say @mohit and from further testing, yes it seems that the Poweshield behaves as you say, taking priority of the DC when DC+LiPo exists, provided the DC voltage is above a certain threshold (which seems ~6-7 volts).
The 3 scenarios I am thinking of were;
Mains wall-socket connects to DC; the connected LiPo acts as a “keep-alive” for whenever the wall-socket has a brownout/blackout/failure.
Large long-life battery connects to DC; the connected LiPo acts as a “keep-alive” for whenever the large battery connected to DC needs disconnecting or replacing.
Solar panel array connected to DC; the connected LiPo acts as a “keep-alive” or “fallback” whenever the solar panel array cannot supply enough voltage, eg during bad weather, night time, etc.
It seems all this was already considered and designed into the current way the Powershield works, which is pretty darn neat to be honest!