TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred System: In the system above, voltage between the electrodes is a function of whether fluid in the cell stack assembly is in contact with both of the electrodes. The fluid is contained in the cell stack assembly. It comprises an electrically conductive coolant. The fluid comprises water. At least one of the electrodes is positioned to indicate a level of the fluid in the cell stack assembly. The cell stack assembly further comprises a fluid manifold, and where at least one of the electrodes is positioned within the fluid manifold, where the fluid manifold is a fluid inlet manifold or a fluid outlet manifold. The cell stack assembly also comprises a fluid channel, and where at least one of the electrodes is positioned within the fluid channel, where the fluid channel is part of a fluid loop. The fluid detection system further comprises a controller in communication with the electrodes, where the controller comprises a voltage detection device. The controller further comprises an on/off switch, where the on/off switch communicates with a fluid management system. A lack of a measured voltage by the voltage detection device turns the on/off switch to an on state, and where the on state signals to the fluid management system to supply a fluid to the cell stack assembly. A measured voltage by the voltage detection device turns the on/off switch to an off state, and where the off state signals to the water management system to stop a supply of a fluid to the cell stack assembly. The second sensing element is positioned to contact the fluid. The first sensing element is positioned to indicate a level of fluid in the cell stack assembly. The cell stack assembly further comprises a fluid manifold, and where the first sensing element is positioned within the fluid manifold. Additionally, the cell stack assembly comprises a fluid channel, and where the first sensing element is positioned within the fluid channel. The fluid detection system further comprises a controller in communication with the first sensing element and the second sensing element. A lack of output provided by the voltage sensor turns the on/off switch to an on state, and where the on state signals to the fluid management system to supply the fluid to the cell stack assembly. An output provided by the voltage sensor turns the on/off switch to an off state, and where the off state signals to the water management system to stop a supply of the fluid to the cell stack assembly.