Enter your battery's voltage and amp-hour rating, and you'll instantly see the stored energy in watt-hours, along with C-rate, discharge current, and estimated runtime. A lead-acid battery can store **a significant amount of energy depending on its specifications, 2. The storage capacity typically ranges from **50 to 200 amp-hours, 3. Understanding the intricacies of lead-acid. The first step in calculating the power storage capacity of lead acid batteries is to determine the battery voltage. Therefore, a 12V battery will have 6 cells, a 24V battery will have 12 cells, and so on. Load Power Consumption (W) Enter the total power drawn by your device (s).