Sensors

The sensors in a battery could be all or a subset of the following:

• Cell voltage
• Current flow
• Cell temperature
• Humidity
• Fluid level
• Pressure
• Gas composition
• Pack voltage
• Isolation Resistance
• Earth Bonding Impedance
• Coolant temperature(s)
• Coolant flow rate
• Force / deformation
• Dielectric strength of coolant

Some of these might be direct measurements and some might be an estimation. A fusion of sensor data over time is often used to estimate other parameters and hence form virtual sensors.

The minimum for the simplest of battery packs would be temperature and cell voltage. The single battery cell in a mobile phone would have voltage and temperature sensors.

Note: main image courtesy of ATC Semitec distributors of thermal components working with world leading innovative suppliers in the NTC Thermistor, Platinum RTD and Thermostat industries.

Future Roadmap for Sensors

Smart Sensors

The future is possibly a Smart Battery Cell where the sensors are built into the cell when it is in production. This will give:

• Have the ability to modulate or isolate the electrical current flowing through the terminals.
• Have the ability to measure key internal variables such as electrode potentials, current, temperature, mechanical stress and internal pressure.
• Be able to resolve measurements both spatially and temporally.
• Include localised control and communication hardware to integrate the LIB with its external environment without adding complexity via wireless or powerline data-transfer.