Xantrex DR1512W Installation And Operation Manual

Also see for DR1512E: Installation & operator's manual

Contents

Xantrex DR1512W Installation And Operation Manual Manual pdf 95 page image

Battery Bank Sizing975-0012-01-02 Rev A B–5Back up power systems which use utility power for recharging should use theestimated number of days of maximum power outage for determining days ofautonomy.Understanding Amp-hour RequirementsAmp-hours To estimate the battery bank requirements, you must first calculate the amount ofpower you will draw from the batteries during your period of autonomy. Thispower draw is then translated into amp hours (Ah)—the unit of measure toexpress deep-cycle battery capacity.Amp hours are calculated multiplying the current drawn by the load by the lengthof time it will operate.Watts to amps To calculate amps when the power consumption is expressed in watts, use thefollowing equation:A = W/Vwhere W = watts and V = volts DCFor example:A 100 watt light bulb will draw approximately 8.33 amps8.33 = 100 /12If the light runs for three hours it will consume (8.33 x 3) or 25 Ah of power.Time and power The length of time a load is operated will affect the power draw. In some cases, anappliance which draws a large wattage may not consume as many amp hours as aload drawing fewer watts but running for a longer period of time.For Example:A circular saw draws 1500 watts or 125 amps. It takes 5 seconds to completea cross cut. Twelve such cuts would take a minute and you would consume 125A x 0.016* hour = 2 Ah*1/60 = 0.016Observation The circular saw, while it draws more power, consumed feweramp hours of electricity because it ran for a short period of time.Calculating Amp HoursCalculations To determine the amp hours you will consume, you need to list your anticipatedloads and the length of time you will operate each one. Determine the number ofhours per day and the number of days during the week you will use the appliance.For example, you use the microwave every day, but a breadmaker only once aweek. If you use an appliance for less than an hour, express the time as a decimalportion of an hour.Amps to watts All electrical appliances have labels which state their energy consumption. Lookfor an amps rating on motors and a watts rating on other appliances.If the label plate has expressed power consumption in amps, multiply by volts forthe watts required. (watts = volts x amps).