Battery system, vehicle, and battery mounted device

摘要

A battery system comprises one or more lithium ion secondary batteries, charge and discharge control means, and internal resistance detecting means. The charge and discharge control means comprises a plurality of mode control means including third mode control means and fourth mode control means, mode selecting means for selecting one mode control means to be used from the plurality of mode control means, wherein a charge current by the third mode control means is made smaller in a predetermined charge condition and equal to or smaller in other charge conditions than a charge current by the fourth mode control means, and the mode selecting means is configured to select the fourth mode control means when the internal resistance detecting means detects or estimates that the internal resistance is relatively high, and to select the third mode control means when the internal resistance detecting means detects or estimates that the internal resistance is relatively low.