IEEE 1660:2008 pdf free download – IEEE Guide for Application and Management of Stationary Batteries Used in Cycling Service
Battery construction,operation， and maintenance are very different for each of these two applications.While some batteries are capable of both standby and cycling service, using a battery specifically designedfor standby service in a cycling application may result in short life and poor performance, and vice versa.Therefore, the correct battery must be selected for each application and the correct maintenance standard(s)and recommendations followed for the application.
Typical applications in the standby category include telecommunications backup, emergency lighting, andUPS. Typical stationary cycling applications include off-grid renewable-energy applications, such as Pv,and grid-connected applications, such as DER.See Table 1.
Standby battery charge/discharge characteristics are well defined and straightforward.The batteries are in afloat condition for indefinite periods and deliver power to the load infrequently. Sulfation of the plates andfrequent equalization are 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 alreadyexist, this class of applications will be used throughout the remainder of the guide as the primary exampleof a cycling application.
An example of a stand-alone remote PV home* will be used to describe a typical cycling application of astationary battery. A block diagram of the system is shown in Figure 1.Charge/discharge cycles for themonth of December are shown in Figure 2 and Figure 3. Daily DOD is 15% to 25%(monthly average,20.3%), but on days with little sun the DOD reaches 50%. In areas with significant seasonal variability, thedaily 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 andfor seven days after the capacity test.Note that the amount of equalization charge was dependent onavailable charging current (available sunlight). Failure to equalize the battery in this application candegrade capacity by 50% in 1 2 months.
Figure 3 shows battery voltage, PV current, and load current of the same system as Figure 2. In order todifferentiate PV array current from the 6.5 kW standby engine-alternator charging current, the chargingcurrent (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,forexample,lights,TV, washer/dryer,office equipment,hair dryer, and water pump.Average battery loadcurrent for the month was 10.1 A, and the maximum hourly average was 52.4 A.
4.3 Charge efficiency
The energy efficiency of a battery is the energy in watthours (Wh) discharged divided by the energy inwatthours for a complete recharge, and is usually around 70% to 80% for lead-acid batteries.Energyefficiency of a cycling battery is one factor in determining the recharge time. However，in manyapplications，including most PV systems, ampere-hour (coulombic) efficiency is a more important valuebecause the charging device is a current source, not a voltage source. It should also be borne in mind thatthe recharge of batteries in renewable-energy applications is impacted by the available magnitude andduration of the generated power (see 6.2).
The ampere-hour efficiency of a storage battery or cell is the electrochemical efficiency expressed as the ratioof ampere-hour output to the ampere-hour input required for a complete recharge.The incremental ampere-hour efficiency is called charge acceptance,which is the ability of a battery,when charging, to convert itsactive materials into a form that can subsequently be discharged.Charge acceptance is quantified as the ratio,expressed as a percentage, of the charge ampere-hours stored during an increment of time to the total chargeampere-hours supplied during that time.The charge acceptance for a vented lead-acid battery is nearly 100%until the battery reaches approximately 80% SOC, and decreases to 0% at 100% SOC.