What Makes Deep Cycle RV Batteries Different?

Deep cycle RV batteries are one of the three commonly-available types of RV batteries, but they’re the ones that are most often misunderstood. With this post, we hope to change that, at least to some degree.

An RVer’s access to power is no minor consideration. We all appreciate traveling with the ability to run a number of appliances and electronic devices. While some RVers accomplish this by being tethered to campground power pedestals, other travelers (like us!) prefer to boondock in the forest, in the desert, on the beach, or even in a parking lot on our way to another great destination! To do that, however, we need battery power.

There are many options for RV batteries, but this post is geared toward understanding the popular RV deep-cycle battery.

Let’s get to it!

What Are the 3 Most Common Types of (Non-Lithium) RV Batteries?

The three most common types of RV batteries that are not lithium ion (typically for RV use, Lithium Iron Phosphate) batteries are starting batteries, deep cycle batteries, and marine batteries.

Let’s take a look at each of these three battery types, how they work, and the jobs they’re designed to do.

Starting Batteries

Starting batteries are designed to provide the short but powerful burst of energy required to start an engine and to power the typical small 12V DC loads that a car might have. They provide their maximum power for about one to three seconds.

They typically have a larger number of thinner lead plates, allowing them to discharge in a burst and recharge quickly.

Starting batteries are easily damaged by being drained too low. So, while they can provide high current, they can’t handle deep discharges without suffering permanent damage and/or dramatically decreased lifespan.

Deep Cycle Batteries

Deep cycle batteries are designed to provide a long, steady supply of power rather than short power surges. (This is the key difference!)

These batteries are constructed using a smaller number of thicker lead plates, giving them greater resistance to damage from many cycles of being drained (reasonably) and recharged.

Deep cycle batteries can be drained and recharged many times over. However, it’s best not to deplete a deep cycle battery below a 50% state of charge. For example, if you have a deep cycle battery rated to provide 100 amp-hours of energy, you don’t want to use more than 50% of that energy, or 50 amp-hours.

The big difference between deep cycle batteries and other common batteries is the ability of the deep cycle battery to handle multiple cycles of deep discharge. This is important to the process of providing DC power for RV use.

Marine Batteries

Marine batteries can be starting, deep cycle, or dual-purpose batteries.

A dual-purpose battery is kind of a hybrid between a starting battery and a deep cycle battery. It can provide the strong burst of power needed to start an engine as well as provide more long-term power for onboard accessories due to having slightly thicker lead plates.

But, it’s important to know that not all “marine” batteries are necessarily “deep cycle”.

So, unless you confirm that you’re getting a deep-cycle marine battery, you could end up with one that doesn’t meet your needs for providing off-grid power for any length of time. It would also likely become damaged by continuous cycles of deep discharge.

Should an RV House Battery Have High CCA (Cold Cranking Amps)?

In a word? No!

CCA (Cold Cranking Amps) is a measure of a battery’s output capacity for starting an engine. In other words, CCA represents the battery’s ability to provide short, powerful bursts lasting from 1-3 seconds.

You need that power in a short burst to start an engine, but it’s not what you need for a house battery that needs to provide steady, continuous power.

You actually want to avoid batteries advertised for their high CCA because they’re unlikely to have lead plates thick enough to be effective as deep-cycle batteries.

Again, while high CCA may indicate that a battery is great for starting an engine, it’s not so great for providing the long, steady supply of power required by the “house” portion of your RV.

Do Most RVs Come With Deep-Cycle Batteries?

Most RVs come with deep cycle batteries for powering the house portion of the RV. But if you’ve got a motorhome your RV will have two types of batteries.

Let’s use our RV as an example:

Our RV came with a pair of starting batteries for the engine, and a second set of deep cycle batteries for running the house loads.

Our 43′ Class A RV came with four 6V deep cycle RV batteries. This means that our rig came with two pairs of batteries wired in series, (positive-to-negative), to create two larger 12V batteries that were then wired together in parallel to increase the amp-hour capacity of the combined set. (NOTE: We later upgraded to lithium batteries which you can read more about in part four of our post on our lithium-AGM electrical upgrade.)

Be aware, though, that RVs can come with either 12V or 6V deep cycle batteries.

6V batteries (commonly referred to as “golf cart batteries”) are a type of deep cycle battery that always come in pairs, wired in series (positive terminal to negative terminal), to make one larger 12V deep cycle battery.

This increases their amp hour (ah) capacity, which is the amount of energy they can supply before needing to be recharged.

6V deep cycle batteries usually come in the same form factor as 12V, so within that same size/footprint they can have even thicker lead plates and improved resistance to damage from repeated (deep) charge/discharge cycles.

The thick plates also contribute to the increased amp-hour capacity.

For more detailed information on the differences between lithium RV batteries, AGM batteries, and standard flooded lead acid batteries, take some time to watch our presentation, RV Battery Types Compared: Lithium vs AGM vs Flooded Lead Acid:

What Are the Best Deep Cycle Batteries for RVs?

Let’s look at three levels of good deep cycle batteries for RV use.

Interstate M-GC2-UTL

This entry-level 6V flooded lead-acid deep-cycle battery provides 210 amp hours of power and comes with a 12-month warranty. Our RV came with a set of four 6V deep-cycle Interstate batteries (a model very much like this, but since discontinued), and they worked great for us for many years.

Trojan T105

The Trojan T105 is a top-of-the-line 6V flooded lead-acid deep cycle battery. A single Trojan T105 provides 225 amp hours despite being a small (62-pound) 6V battery. (Remember that 6V batteries are purchased in pairs.)

Our first RV (our 2002 Fleetwood Bounder Diesel), had a set of four of these.

Lifeline GPL-4CT AGM

This is a high-quality 6V AGM (Absorbed Glass Mat) deep cycle battery made in the USA. Each single battery provides 220 amp hours of power.

Pairs wired in series (positive terminal to negative terminal) become one much larger 12V battery. In a common RV application, a second series-wired pair will be wired in parallel with the first, keeping the voltage at 12V, but doubling the total amp-hour capacity (to 440 Ah).

When we had to replace the Interstate deep-cycle batteries that our current RV came with from the factory, we upgraded to a set of these. In addition to providing enhanced resistance to damage (sulfation) from repeated deep cycling, as a sealed battery AGMs also reduce/elminate the regular maintenance a wet cell, flooded lead-acid battery requires (adding distilled water to replace what escaped through the vents in the battery caps).

Can I Replace My Deep Cycle RV Batteries Myself?

You can replace your RV’s deep cycle house batteries as long as you’re able to lift them, or have someone who can lift them into position for you. (These batteries are generally between 60-70 pounds apiece.)

If you’d like to take on this important DIY project, we invite you to take a look at our post on how to replace RV house batteries.

Whether your RV has 12V, 6V (golf cart), or AGM batteries, in this video we’ll show you exactly how to replace them when the time comes!

If, after watching the video above, you’re uncomfortable replacing your RV’s batteries yourself, have a professional install them for you. It’s important that your RV’s electrical system is set up properly.

As we’ve always said, part of being a wise DIYer is knowing when a project is beyond your ability or comfort level.

When we switched to the Xantrex Freedom eGEN lithium battery we now have in our RV, we elected to have a professional install it for various important reasons. The last thing we wanted to do was make a misstep that would fry our RV’s electrical system or damage electrical components in the rig.

But replacing your RV’s old deep-cycle batteries with new ones is a pretty straightforward process. So, if you’re comfortable with the project, just follow along with our video above and update your rig’s power supply.

Then head out on an awesome boondocking adventure and enjoy having plenty of power wherever you go.

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