STEP 3 Calculate total watt hours of energy consumption total hours running

# Step 3 calculate total watt hours of energy

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STEP 3 Calculate total watt-hours of energy consumption, total hours running time, and average power con- sumption as in the following example: Equipment Power Consumption Operating Time Watt - Hours (Power x Operating Time) TV & VCR 115 watts 3 hours 345 Sewing Machine 150 watts 1 hour 150 Waterpik 90 watts 0.25 hour 22.5 Blender 300 watts 0.25 hour 75 Coffee Maker 750 watts 0.3 hour 225 Coffee Grinder 100 watts 0.l hour 10 Microwave Oven 800 watts 0.5 hour 400 Totals 5.4 hours 1227.5 watt-hours
9 INVERTER BATTERY SIZE OUTPUT BCI GROUP SIZE: 20NF 24 27 8D DUAL 8D's POWER TYPICAL LOAD RESERVE CAPACITY 90 MINUTES 140 MINUTES 180 MINUTES 400 MINUTES 900 MINUTES (WATTS) AMP-HRS: 50 75 100 200 400 50 STEREO SYSTEM OPERATING TIME: 9 HOURS 14 HOURS 20 HOURS 40 HOURS 80 HOURS 100 19" COLOR TV OPERATING TIME: 4 HOURS 6 HOURS 10 HOURS 20 HOURS 40 HOURS 200 COMPUTER SYSTEM OPERATING TIME: 2 HOURS 3 HOURS 4.5 HOURS 10 HOURS 20 HOURS 300 BLENDER OPERATING TIME: 1.3 HOURS 2.2 HOURS 3 HOURS 6 HOURS 12 HOURS 400 POWER DRILL OPERATING TIME: 1 HOUR 1.5 HOURS 2 HOURS 4.5 HOURS 10 HOURS 600 SMALL COFFEE MAKER OPERATING TIME: N.R. N.R. 1 HOUR 2.5 HOURS 6 HOURS 800 SMALL MICROWAVE OVEN OPERATING TIME: N.R. N.R. N.R. 1.5 HOURS 4 HOURS N.R. - NOT RECOMMENDED Figure 6. 12 Volt Battery Sizing Chart Average Power Consumption = 1227.5 watt-hrs ÷ 5.4 hours = 227 watts 12 volt Ampere-Hours Consumed = Watt-hours ÷ 10 = 1227 ÷ 10 = 123 ampere-hours or, for PW800/24 volt system , Consumption = 1227.5 watt-hours = 227 watts 24 volt Ampere-Hours Consumed = Watt-hours 20 = 1227 20 = 62 ampere-hours STEP 4 Using the chart above (figure 6), find the battery size that will give you the required operating time at the calculated average power consumption. For instance, from the example above, the required oper- ating time is 5.4 hours and the average power consumption is 227 watts. From the chart, the smallest battery size that will give more than 5 hours of operation at a power level between 200 and 300 watts is the 200 amp-hr. battery, which offers between 6 and 10 hours of operating time. When sizing your battery, be generous. More capacity is better since you will have more reserve capacity, and your battery won't be discharged as deeply. Battery life is directly dependent on how deeply the battery is dis- charged. The deeper the discharge, the shorter the battery life. Ideally, the number of ampere-hours consumed by your loads before recharging the battery should be no more than 50% of the battery's rated capacity. Using Multiple Batteries To obtain sufficient battery capacity you may need to use more than one battery. Two identical batteries can be connected + to + and - to - in a parallel system that doubles capacity and maintains the voltage of a single battery. Do not connect batteries from different manufacturers, or with different amp-hr ratings, in parallel. De- creased battery life may result. If you are using different batteries, or need to use more than two batteries, we recommend that you set up two separate battery banks and use them alternately. Battery selector switches are available from marine and RV dealers that allow you to select between two banks of batteries, or use both in parallel, or disconnect both from the load.

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