b'FOGHORN FOCUS The maximum charger er for the sake of brevity, this will be left for the reader to explore. You can see in Figure 4 that AGM (absorbed size is limited by the chargeglassmat)andotherlead-acidbatteriesareaffectedbythisphenomenon in a more pronounced way than their lithi-rating of your battery.um-ioncousinshoweverthereareseveralfactorsincludingsafetyandcostthatwouldmakealead-acidbatterybankabetter choice for your application. knowledge in the case of systems that may have future ex-pansion)sothatyoucanselectanappropriately-sizedbat- Whensizingyourcharger,themaximumchargersizeis tery or battery bank(s), charger(s), and wiring. The batter- limited by the charge rating of your battery. Typically, the ies should be sized in function of how long the electronicsbattery manufacturer will specify the max charge rate in c. should remain powered in the event of a loss of power. TheThis would be the charge current required to fully charge the ruleofthumbistospecifyabatterybankwithanAmp- battery in one hour or the Ah rating of the battery multiplied hours (Ah) rating of 2x the total load in amps multipliedby one hour. The rule of thumb for standard batteries is to se-bytheback-uptimerequiredinhours.Themainreason lect a charger with an output of the Ah rating divided by five. for this is that batteries discharge faster the further dis-charged they are, most batteries dont like to be dischargedThis article is a very simple discussion on batteries and belowa50percentSoC,andbatteriesthathavehadmany batterychargingtechnology.Alwaysbesuretofollow charge-dischargecyclesalsodonotholdachargeaslong. applicable electrical regulations and battery manufacturer This can also be calculated using Peukerts Law howev- recommendations when designing your electrical system.Figure 3BULK ABSORPTION MAINTENANCE(CONSTANT(CONSTANT VOLTS) (CONSTANT VOLTS)CURRENT)100%VOLTS75%50%25%FIGURES COURTESY ANALYTIC SYSTEMS AMPS0%TIMETHREE STAGE CHARGERFOGHORN 14'