The brushless fans are designed to operate with applied voltages from 9V to 16V. if the fan sees a voltage higher than 16V it can turn off. So normally we would recommend using a voltage step down to 12V with the brushless fans on a 16V system. When the fan ramps up, it is likely drawing enough current through the wires with a voltage drop to keep the voltage below 16V at the fan, when the fan is not running there is little/no current draw, the voltage drop would be almost zero, and the fan may be seeing 16V.
The sensor is designed for both 12V and 24V systems, it’s just the fan that doesn’t like 16V. We also have 24V fans available, but they would operate down to 16V and if the voltage went lower they would also shut off. So we don’t have a good brushless solution for a 16V system.
