Abstract: An electrical system and method of operation is disclosed. The electrical system can be an energy storage device operating a load. A battery pack provides power to the electrical system. A processor determines a model of a power schedule of the electrical system, determines, using the model, a test time during operation of the electrical system for obtaining a parameter suitable for calculating a capacity of the battery pack, obtains the parameter of the battery pack at the test time, calculates the capacity of the battery pack using the parameter, and operates the electrical system based on the calculated capacity.

Abstract: Techniques are provided for multi-stage charging control of a vehicle. In one embodiment, the techniques involve determining a charging stage capability of a charging source, upon determining that the charging stage capability includes multi-stage charging, determining a first charging criteria, selecting a first charging circuit configuration based on the first charging criteria, where the first charging circuit configuration includes a first combination of cell groups of a rechargeable energy storage system of the vehicle, charging the rechargeable energy storage system via the first charging circuit configuration, determining a second charging criteria, selecting a second charging circuit configuration based on the second charging criteria, where the second charging circuit configuration includes a second combination of cell groups of the rechargeable energy storage system, and charging the rechargeable energy storage system via the second charging circuit configuration.