How Many Watt-Hours in a Deep Cycle Battery?

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If you’re only just beginning to learn about batteries, you don’t care about becoming a professional electrician, and you only want to know the bare-bone basics of how many watt-hours are in a deep cycle battery, then you’re in the right place!

How Many Watt-Hours in a Deep Cycle Battery?

First off, you’re going to need to look at your battery label and find the volts (usually 6-volt, 12-volt, 24-volt, 48-volt or something similar) and the amp-hours (sometimes you’ll see a number followed by Ah, like 75Ah or 100Ah).

How to Find Watts-Hour with Volts & Amp-Hours

Let’s take a lithium deep cycle battery to understand how to find out how many watt-hours a battery has.

And let’s make this lithium battery a 12-volt / 100 ah battery (which is usually marked on a battery’s label). This is a very common type of battery.

All you have to do is multiply the battery’s volt and its amp-hours, and you get the battery’s watt-hour. So, in the case of our 12-volt / 100 ah battery, you’ll get 1200 watt-hour.

Volt x Amp-Hour = Watt Hour

12 volt x 100 amp-hour = 1200 watt-hour

It’s really that easy!

A Few Things to Consider

When I compare the same types of batteries (usually I only buy lithium batteries or AGM sealed lead-acid batteries), I like to multiply the volt and the amp-hour of the batteries to compare them by their watt-hour.

If we look at two lithium batteries, and one is 12-volts with 50 amp-hours, and the second battery is 6-volts with 100 amp-hours, I’d multiply the volts and the amp-hours to get the watt-hours.

12 volts x 50 ah = 600 watt-hours

6 volts x 100 ah = 600 watt-hours

As you can above, both batteries will give me the same watt-hours.

But what happens if you compare batteries with two different chemistries, like a lithium battery and a lead-acid battery?

Lithium vs Lead-Acid Batteries

One thing to note is that you can discharge (use up) a lithium battery 100% without causing it any harm. However, you can only discharge (use up) most lead-acid batteries around 50% before you start to damage the battery permanently.

So let’s say that you have a 12-volt / 100 ah battery. If it’s a lithium battery where you can use 100% of the electricity it contains, you’ll get 1200 watt-hours from it.

But if you take a 12-volt / 100 ah lead-acid battery, and you can only discharge it to 50%, then you don’t get 1200 watt-hours from it. You really only get about 600 watt-hours from it.

So the amount you can discharge a battery is also something to consider when comparing batteries.