I am controlling a robot via usb from an Android phone running the robot's code. This phone has a poor battery and I need to extend its life with a USB charger (can't change phones). How can I charge an android phone via usb, while maintaining a USB connection to the robot? I can solder wires together if needed, or can buy adapters as needed.

an image of a robot, phone, and battery all connected by USB. The phone is charged by the battery while still controlling the robot by USB


1 Answer 1


You just need a DC-DC converter. This will take care of stepping down the voltage from battery to USB power specs. You may buy the ICs online and solder them or look for a breakout boards for quick setup.

Alternatively, you can look for USB car chargers or LiPo BEC (Battery Elimination Circuit). You can break open the Car USB charger (which has the cigar lighter mount), and solder the battery leads to those terminals (https://www.youtube.com/watch?v=2IOs3g-52Zo , Omit the variable voltage part. You can just use the USB power)

LiPo BEC Option: https://www.youtube.com/watch?v=Uj4bSOg27T0


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