For instant, if you're running a 100A load on a 100Ah battery, it will last 35-40 minutes instead of 1 hour. Note: If the load capacity is mentioned in watts, make sure it should not exceed the total watt-hour (battery Ah x Battery volts) capacity of the battery. But one question comes up constantly: "How long will it take to charge?" The short answer? It depends entirely on your charger's amperage. In. ?Long Lasting & Charging More Than 4X Faster?Our 12. 8V 100Ah lithium battery has 1280Wh energy (12. 8V×100Ah×100%DOD=1280Wh), which is close to the real energy of 12V 200Ah lead-acid battery (12V×200Ah×60%DOD=1440Wh), as the depth of discharge (DOD) of lead-acid is about 60%. High frequency chargers like this 14. 6V 20A LiFePO4. The LiFePO4 Battery Runtime Calculator is designed to help you predict the runtime of Lithium Iron Phosphate (LiFePO4) batteries. By using this. For example, a 100Ah lithium battery indicates it can theoretically supply 100 amps of current for 1 hour or 10 amps of current for 10 hours at standard temperature (25°C) in a rated voltage.