Overview of Article

This article will overview the description of the characterization of battery efficiency of Midnight Sun. It will overview the physics of the system, the inputs of the system and the outputs.

Physics of System

The main efficiency losses of the system come from the resistances in the system. When passing current through a resistor, power is lost in heat. A simple equivalent circuit model of a cell consists of the cell and a small resistor in series. Power loss occurs when current flows to charge or discharge the cell. 

Currently, the resistance in the pack is modelled as constant, however, the internal resistance of the cells changes with SoC and with temperature. Mock data for these parameters is easy to gather from research articles, but could be collected via a script running on the electrical equipment in the bay.

Inputs of System

The model takes as an input the required output power at the terminals of the battery box, and calculates the required power at the cells (before the power lost over the internal resistance), and returns the efficiency of the system considering the power lost in the resistance of the pack.

Outputs of System

An efficiency number on the energy being consumed by the car. This number will be (power delivered to the outside of the pack) / (total power delivered by the batteries). The energy burned off as heat (the difference between the two numbers) will also be available.