How long will a 200ah battery last

How long a 200ah battery will last depends on a number of factors, including, the efficiency of your inverter, depth of discharge, and how much load you are running. A new 200ah deep cycle battery connected to a 12v inverter, will last 10 hours if discharged with a load of 150 watts at 80% efficiency and depth discharge. If your load is 300 watts, however, the battery will only last for about half that time.

How to calculate Inverter battery backup time

To find how long will a 200ah battery last, first, you'll need add up the total wattage of the devices you want to power with your 200ah battery bank. Let's say you want to power six 9-watt LED light bulbs, a 45 watt TV and a 90 watt fan for 10 hours.

You will not only need an inverter capable of carrying the load, but also a battery bank capable of powering the load for the required backup period.

After you have determined your load's power consumption, the efficiency of the inverter, size and voltage of the battery bank, you can use this formula to determine how long will a 200ah battery will last:

12v (Battery Bank Voltage) x 200ah (Battery Capacity) x 0.8 (Depth of Discharge) x 0.8 (Efficiency) / 189 watts = 8 Hours

The above result shows that a single 200ah battery cannot power a load of 189 watts continually for 10 hours (at 80% depth of discharge and efficiency) to get the desired result (without damaging the battery) you would need to add an additional battery.

12v (Battery Bank Voltage) x 400ah (Battery Capacity) x 0.8 (Depth of Discharge) x 0.8 (Efficiency) / 189 watts = 16 Hours

Examples