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Method to determine the SOH of a battery



Statut des brevets

Priority patent of invention n° FR 1359508 filed in October 1, 2013, entitled ” Procédé et appareil d’évaluation de l’état de santé d’une batterie lithium»



Jean-Michel VINASSA
Olivier BRIAT

Statut commercial

Exclusive or non exclusive licenses.


Laboratoire de l’Intégration du Matériau au Système (IMS, UMR5218), Bordeaux, France



Lithium ion batteries are widely spread nowadays to power most of electronic devices and even for electric vehicles or energy storage systems. Lifetimes of these batteries are related to their way of use and BMS are mandatory to control charge level, to balance between the cells in a battery pack,…
The determination of the State of Health (SOH) is an important part of BMS for EV or HEV batteries.


The invention relates to a new method to evaluate the state of health of lithium ion battery.
In BMS, SOH is evaluated through the measurement of parameters related to the performance of the battery (usually internal resistance and capacity).

The charging process of industrial lithium ion battery is performed in two phases. A first step with a constant current, and a second step with a constant voltage. This second step is stopped when the current reaches a specified low value.

Development stage

The invention uses the time of the CC-CV charge process in order to evaluate the SOH of the cell. A simple exponential model easy to implement shows a good fit with experimental data. The model was tested for the main cathode materials (LMO, NCA, NMC). The model could be adapted to fit the specific behavior of LFP cathode.



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