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. <EOS>