A 12v 100ah lead-acid battery with a 50% DoD limit will run an appliance that requires 80W for about 6.8 hours
Keep reading I’ll explain how you can calculate how long will your 100ah battery run on an 80-watt appliance
How long will 100ah battery last – calculator
Note! use my solar panel size calculator to find out what size solar panel you need to recharge your battery in desired hours with solar panels.
Inverter Efficiency: 90%
Lead-acid battery: 50% depth of discharge limit
Lithium (LiFePO4): 100% depth of discharge limit
Battery Depth of discharge DoD: is the percentage of the battery that has been discharged relative to the total battery capacity. The recommended depth of discharge limit for lead-acid, AGM, and gel batteries is about 50%. Only lithium (LiFePO4) batteries can be fully discharged to 100%.
How To Use The Calculator
Enter the battery capacity in amp-hours (Ah): in this case, it’ll be 100
Enter the battery voltage: is this a 12, 24, or 48-volt battery?
Select the battery type: Select “Lead-acid” if you’re using a flooded or sealed (AGM or gel) lead acid battery. Select “Lithium (LiFePO4)” if you use a lithium-iron-phosphate battery.
load Connected with inverter?: Are you using an inverter to run the load or is the load connected directly through the battery?
Enter total load in watts: Enter the total load in watts (e.g 80 for 80 watts of output load)
After entering the information, click “Calculate” button to find out how long the battery last running a load.
Video – Solar battery 101
Steps To Calculate 100ah Battery Runtime On 80-Watt Appliance
Follow these steps to calculate the 100ah battery life/runtime while running a 80w load.
1- Converter battery ah into watt-hours (Wh). to calculate the battery capacity in watt-hours use this formula
2- Multiply the battery watt-hours by the battery depth of discharge limit. ( Default battery depth of discharge limit, Lead-acid battery: 50% DoD limit; Lithium: 100% DoD limit ). Let’s say you have a lead-acid type battery
Battery capacity in wh after DoD limit = 1200 * 50% = 600wh
3- Multiply the battery capacity after the DoD limit with the inverter efficiency rate to calculate the AC watt-hours ( Most of the inverters are about 90% efficient)
Battery AC watts = 600 * 90% = 540 AC watt-hours
4- Divide the battery AC watt-hours by the total load connected. Let’s say 80-watt appliance is connected to your 100ah battery