This disclosure is directed to apparatuses, methods, and systems for detecting a capability of a power source connected to a device. For example, a device may include a standardized connector that may allow an unknown power source to provide power to the device. When a power source is connected with a device, a controller powers up and initiates power capability detection procedures. A ramping current sink begins drawing current from the power source at an initial value and increases that amount to a maximum current value. If a voltage on the device voltage bus falls below a voltage threshold during the ramping current sink operation, the current sink is disconnected and an indication is provided to the controller that the power source is underpowered. Further, a safety timer turns off the ramping current sink to prevent excessive heat generation.