IEEE Std 1660-2018 pdf download – IEEE Guide for Application and Management of Stationary Batteries Used in Cycling Service.
Standby battery charge/discharge characteristics are well defined and straightforward. The batteries are in a float condition for indefinite periods and deliver power to the load infrequently. Sulfation of the plates and frequent equalization are typically not issues. Cycling battery charge/discharge characteristics are very different from those of standby batteries, especially for renewable-energy applications such as PV. Because standards for PV applications already exist, this class of applications is used throughout the remainder of the guide as the primary example of a cycling application. An example of a stand-alone remote PV home 3 will be used to describe a typical cycling application of a stationary battery. A block diagram of the system is shown in Figure 1. Charge/discharge cycles for the month of December are shown in Figure 2 and Figure 3. Daily DOD is 15% to 25% (monthly average, 20.3%), but on days with minimal solar irradiance the DOD reaches 50%. In areas with significant seasonal variability, the daily cycles may be superimposed on a periodic or seasonal cycle that may be as deep as 80% DOD. The charge controller was set to provide an equalization charge for three days prior to the capacity test and for seven days after the capacity test. Note that the amount of equalization charge was dependent on available charging current (available sunlight). Failure to equalize the battery in this application can degrade capacity by 50% in 12 months. Figure 3 shows battery voltage, PV current, and load current of the same system as Figure 2. In order to differentiate PV array current from the 6.5 kWstandby engine-alternator charging current, the charging current (A) is shown as a negative load current. Battery loads vary constantly throughout each 24 h day as loads are turned on and off. Loads include, for example, lights, TV, washer/dryer, office equipment, hair dryer, and water pump.Average battery load current for the month was 10.1 A, and the maximum hourly average was 52.4 A.