A system, comprising: a voltage supply configured to supply an output current to a load; testing circuitry coupled to the voltage supply, wherein the testing circuitry comprises: an additional voltage supply; a switch configured to close in response to a voltage signal from the additional voltage supply; and a current measurement circuit configured to couple to the switch, wherein the current measurement circuit is configured to receive the output current from the voltage supply while the switch is closed and while the voltage supply is operating in a secondary supply role for the load; a diode coupled with the load, wherein an anode of the diode is arranged towards the voltage supply; and a control system configured to: receive an indication of a voltage across the current measurement circuit while the switch is closed from a sensing circuit; determine an amount of current present in the output current based on a resistance value associated with the current measurement circuit and the voltage; and perform an operation based on the amount of current. a voltage supply configured to supply an output current to a load; testing circuitry coupled to the voltage supply, wherein the testing circuitry comprises: an additional voltage supply; a switch configured to close in response to a voltage signal from the additional voltage supply; and a current measurement circuit configured to couple to the switch, wherein the current measurement circuit is configured to receive the output current from the voltage supply while the switch is closed and while the voltage supply is operating in a secondary supply role for the load; a diode coupled with the load, wherein an anode of the diode is arranged towards the voltage supply; and a control system configured to: receive an indication of a voltage across the current measurement circuit while the switch is closed from a sensing circuit; determine an amount of current present in the output current based on a resistance value associated with the current measurement circuit and the voltage; and perform an operation based on the amount of current. an additional voltage supply; a switch configured to close in response to a voltage signal from the additional voltage supply; and a current measurement circuit configured to couple to the switch, wherein the current measurement circuit is configured to receive the output current from the voltage supply while the switch is closed and while the voltage supply is operating in a secondary supply role for the load; a diode coupled with the load, wherein an anode of the diode is arranged towards the voltage supply; and a control system configured to: receive an indication of a voltage across the current measurement circuit while the switch is closed from a sensing circuit; determine an amount of current present in the output current based on a resistance value associated with the current measurement circuit and the voltage; and receive an indication of a voltage across the current measurement circuit while the switch is closed from a sensing circuit; determine an amount of current present in the output current based on a resistance value associated with the current measurement circuit and the voltage; and perform an operation based on the amount of current.