Battery Testing Methodology
The purpose of the ITP lithium-ion battery trial is to conduct accelerated testing of batteries for “typical” Australian conditions. ITP will cycle the batteries up to three times a day for three years to simulate nine years worth of “normal” daily cycling of the batteries. ITP will monitor the capacity of the batteries tested over this period to assess their performance.
Given that most battery systems in residential or small commercial systems are expected to be sheltered from rain and direct sunlight but be exposed to outdoor temperatures, ITP is varying the ambient temperature in the battery testing room on a daily basis, varying throughout the year. The high and low temperatures are given in Table 1 below.
To get meaningful results, all of the batteries will undergo charge/discharge cycles at the same ambient temperature. ITP will submit the batteries to “summer” and “winter” temperature regimes, whereby the batteries will undergo two cycles per day at the monthly high temperature in summer months (Nov to Apr), and two cycles per day at the monthly low temperature in the winter months (May to Oct).
Once a month, the batteries will undergo a single cycle at 25 °C, as this is the reference temperature at which manufacturers provide the capacity of their batteries. This cycle will be used to calculate the capacity of each battery that will be considered for the purpose of assessing capacity fade over time.
Given the focus on energy efficiency and low energy consumption at the CIT Sustainable Skills Training Hub, the timing of the high and low temperature cycles will be matched with the variations of outdoor temperatures, to allow transitions between high and low temperature setpoints to be assisted by outdoor air.
The schedule of charge and discharge cycles given in Table 2. Figure 2 and Figure 3 provide indicative SOC plots for batteries being discharged to 80% DOD.