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Lithium Battery Run Time Calculator for Marine Electronics

Use this calculator to determine what size 12V lithium battery you need to run your marine electronics. We use this lithium battery run time calculator to figure out what Ah rating our customers will need for clean power installs.

This calculator is used for LiFePO4 lithium batteries which are used in most boat applications.

How to Calculate Lithium Battery Run Time LiFePO4

First you need to find the total amp draw of all devices on your system.

If we have the following devices on our system:

 Humminbird Helix 5 .65 amps
Humminbird Helix 7  .80 amps
Humminbird Helix 9  2.4 amps


Total Amp Draw = .65 + .80 + 2.4 = 3.85 Amps

Second, calculate total watts being consumed using the amps.

Watts = 3.85 amps * 12 volts = 46.2 Watts

Finally, we can figure out what our Ah rating requirements must be by utilizing our desired run time.

Say we want to make sure we have enough power to run our marine electronics for 6 hours. 

Ah Requirement = Desired Run Time X Total Watts divided by 12.8 Volts (12.8V is the output of LiFePO4 batteries)

In this case our Ah requirement would be: 6 hours X 46.2 watts divided by 12.8 volts

Doing the math we come up with a lithium battery of 21.7Ah's or greater to run our electronics for 6 hours.

 Have questions on calculating lithium battery run time for your marine electronics? Reach out to us here.