Battery Run Time Calculator

Do you have a 12v device you need to power but don't know what 12-volt battery you need? For those running a continuous 12-volt load, an adequately sized deep-cycle battery is a must.

This calculator is designed to provide an appropriately sized AH (Amp Hours) rated battery without excessively discharging the battery below 50%.

So, if you know how much power your application takes to run and how long you would like to run it. Then plug those figures into the calculator, and we will give you our recommended AH rating you need to look for!

Remember, if you use a power inverter, you must first convert the AC Amps to DC Amps before using this calculator.

Battery Capacity Needed

12V Load

Watts OR Amps

Time

Hours

Amount of time you want to run your load.

Factors

Battery temperature
below 0° or over 85° F Battery over 6 months old

Type

AGM Flooded Gel

Calculate

Result

With a safe 50% max discharge level.

Choose Your Battery

(Note* if you are running AC devices, you will need to figure out the DC amperage using our DC to AC calculator).

(Note** if you are using Gel batteries in temperatures below 0 deg F but above -60 Deg F, there is no need to check the box.)

To help you understand, an example is a 15 amp swamp cooler will run safely for 5 hours with a 180 AH, rated at 20 Hours, with an AGM battery. For a little more detail on the math check out our Math Behind the Magic article.