Power Electronics Battery Charging System Supplying Power to
Power Electronics • Battery • Charging System • Supplying Power to Ink
Choosing the Battery • Battery Type has to first be chosen “Batteries and Charge Control for Stand-Alone Photovoltaic Systems : Fundamentals and Applications” , James P. Dunlop
Battery Capacity • • How much energy is stored in the battery measured in ampere hours Ah will provide ‘X’ amps of current for ‘Y’ hrs Ah = Device Wattage (W) * Time to run (hrs)/ Battery Voltage (V) From previous calculation we assume the total amount of power that we can use is 29, 000 Wh/m 2 , are prototype is 3’x 5’ (0. 92 m x 1. 525 m) Therefore the total power used in a year can be about 40, 600 Wh Assuming snowfall for 240 hrs a year (59 days for 4 hrs) the average amount of power of the device will be 170 W (40, 600 Wh/240 h) Therefore Ah = (170 W*4 h)/ 12 V = 56 Ah To increase battery performance and life the battery should not be consistently discharged below 60% capacity so to be safe the battery capacity should be about 90 a. H
Battery Options • Trojan Deep-Cycle AGM Battery can be used • 31 -AGM could all be options with 5 hr ratecapacity of 82 Ah • Can be purchased from civicsolar for $270
Battery Chargers • Controls incoming charge of the battery • AGM batteries are INTOLERANT to overcharge • Standard Solar Chargers or MPPT (Maximum power point tracking) charger • MPPT chargers are much more efficient • Standard chargers can lose between 20 -60% of the rated solar panel wattage
Choosing a Battery Charger • Charger needs to be able to handle rated watt, voltage, and current rating of PV panel (charging source) • Charging source is still being determined (Full Panel or select number of cells) • For now we can base the charger chose off a SBM solar 150 W panel with the following specs:
Possible MPPT Charge Controller • Morningstar Sun. Saver 15 Amp MPPT Solar Charge Controller ($225) Power used from possible 150 W: Power= PV Panel Power * Efficiency Power = 150 W * 97. 5% Power=146. 25 Charge Current = Power/Battery Voltage Charge Current = 146. 25 W/12 V Charge Current =12. 2 A Charging Time = Battery Ah / Charge Current = 100 Ah/ (12. 2 A) Charging Time = 8. 2 hrs
Possible Standard Charge Controller • Morningstar SS-20 L 20 Amp PWM Solar Charge Controllers w/LVD ($78) Power used from possible 150 W: Power = Voltage *Charge Current Power = 12 V *8 A Power = 96 W about 66% efficient Charging Time = Battery Ah / Charge Current = 100 Ah/ (8 A) Charging Time = 12. 5 hrs
Ink Power Supply Rtrace 1 RTotal Battery Rtrace 2 Regulating Circuit Rtrace 3 I out Rtrace 4
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