Hydrometer device

An automotive system, comprising:

• a fluid container to be positioned in an automobile and hold a fluid to be used by the automobile;
• a waterproof device container positioned in the fluid container to float on the fluid;
• a capacitive liquid level sensor positioned in the device container to sense an immersion level of the device container;
• and
• a controller positioned in the device container, wherein the controller includes a conversion circuit to convert the sensed immersion level to a digital value, wherein the controller is to determine a liquid density value for the liquid based on the digital value, and wherein the controller is to cause information regarding the liquid to be wirelessly transmitted to a control device in the automobile that is located outside of the fluid container.

A hydrometer device, comprising:

• a sensor structure to be positioned in a container of liquid, wherein the sensor structure includes a capacitive liquid level sensor on a front side of the sensor structure and an inductive sensor on a back side of the sensor structure;
• a float structure to float on a top surface of the liquid and move upward and downward along the sensor structure with changes in a level of the liquid in the container, wherein the float includes magnetic material to interact with the inductive sensor;
• and
• a controller to receive capacitive sensor signals from the capacitive liquid level sensor and inductive sensor signals from the inductive sensor, wherein the controller is to determine a liquid density value for the liquid based on the received signals.