Battery Bank Sizing Calculator
Determine the required battery bank capacity (in Amp-hours) for your solar setup, RV, or backup power system based on your daily energy usage.
System Requirements
Lead-acid batteries usually have a 50% DoD limit to preserve lifespan. Lithium (LiFePO4) can typically go up to 80-100%.
Number of days the system needs to run without recharging (e.g., cloudy days for solar).
Required Battery Capacity
How to Size a Battery Bank
Sizing a battery bank correctly ensures your system has enough power to run your loads without damaging the batteries through over-discharging.
- Total Load & Runtime: Multiply your total power draw (Watts) by the hours you run it per day to get Watt-hours (Wh).
- Days of Autonomy: How many days do you need power without recharging? Multiply your daily Wh by this number.
- Depth of Discharge (DoD): Batteries shouldn't be drained completely. Lead-acid batteries are typically limited to 50% DoD to prolong their life. Lithium batteries can safely handle 80% to 100% DoD.
- System Voltage: Divide the total required Watt-hours by your battery system voltage (12V, 24V, or 48V) to get Amp-hours (Ah).
Formulas Used:
Daily Energy (Wh) = Load (W) × Runtime (Hours)
Total Energy Needed (Wh) = Daily Energy (Wh) × Days of Autonomy
Required Capacity (Ah) = Total Energy Needed (Wh) / System Voltage (V) / (DoD % / 100)