A new method for the operando determination of the state of charge and the state of health of lithium-ion batteries was developed and patented in the battery laboratory at Offenburg University of Applied Sciences. The algorithm is based on using (for the first time in literature) the measured battery voltage as input variable for a mathematical model.

Our new method has considerable advantages compared to the state of the art. For state of charge diagnosis, the algorithm offers the following advantages:

a) Only the voltage, not the current, is required as a measurement input. This reduces measurement cost and complexity in practical application.

b) The algorithm is self-calibrating - "full" or "empty" calibration states are not required.

c) The new method is robust against partial cycles and shows no SOC drift in case of inaccurate current measurements.

d) The algorithm is numerically simple, no filter or observer is required, and it can be easily implemented on standard microcontrollers.

For state of health diagnosis, the algorithm offers the following advantages:

a) aging can be estimated from regular battery operation without the need for artificial full cycles: it is a true operando diagnostic technique.

b) The model does not require aging-adaptive parameters.

c) The state of health is determined using simple calculations; no filter or observer is required.