Quick Answer
To choose the right size battery bank for air conditioning, first determine the total amp-hours required, then calculate the battery bank's depth of discharge, and finally select batteries and a charge controller that match the system's needs.
Determining Amp-Hours Required
When choosing a battery bank for air conditioning, start by calculating the total amp-hours required. For a typical single-phase air conditioner, assume a power draw of 3-5 kilowatts (kW) and a charging efficiency of 80%. Convert the power draw to amp-hours by multiplying by the charging time in hours. For example, a 3 kW air conditioner running for 8 hours would require 24 kWh, or approximately 120 amp-hours.
Battery Bank Sizing and Depth of Discharge
To ensure the battery bank can handle the AC load, calculate the required amp-hours and select batteries that can deliver that capacity. Consider a depth of discharge (DOD) of 50-70% to balance capacity and lifespan. For example, a 120 amp-hours required system with a 60% DOD would need at least 200 amp-hours of battery capacity.
Selecting the Right Components
Choose a charge controller that matches the battery bank’s capacity and the AC unit’s power draw. Select a charge controller with a maximum charge current of 200-250 amps for a 200 amp-hour battery bank. Ensure the charge controller is compatible with the battery type and has features like overcharge protection and temperature compensation.
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