Best RV Battery (Deep Cycle) for 2021: Your Complete Guide

To begin answering this question, you first need to know the kind of batteries an RV needs.

For an RV to function, it needs two types of batteries – one to start its engine if it needs to move, and another to continually power all the appliances and gadgets it has onboard.

To fire up the engine, you need a battery that can supply a massive burst of electricity in a short amount of time. These are called starter batteries, and most car, motorcycle and other automotive batteries fall in this category.

To power your RV’s appliances and other functions, on the other hand, it needs a battery that can provide a constant stream of electricity over more extended periods, recharging and discharging as it goes along.

Starter batteries, unfortunately, do a piss poor job in this regard. Even though you technically can use it this way, we highly discourage it. The repeated charging and discharging would quickly break down the battery faster than you could say, “That was a bad idea!”

You need to invest in something a little more robust. Enter the deep cycle battery.

Deep cycle batteries are made specifically for constant charge and discharge cycles. They’re sturdier, larger and made of thicker plates, which makes them far more efficient at storing and releasing charge than a starter battery.

RV batteries are charged through a power source, such as a charging station commonly found in parks. An important thing to note, though, is that RV deep cycle batteries supply 12V DC power to your rig. Outlets in charging stations, on the other hand, give out 120 AC. 

Make sure you have a power converter installed before plugging in to prevent any catastrophic damage to your battery.

It is important to know that a deep cycle battery's maximum capacity drops once it has reached its rated number of cycles. Since RV deep cycle batteries are an RV battery, the type and size of features to look for are different compared to a typical vehicle battery.

Deep cycle batteries of the highest quality normally hold up for ten to fifteen years before losing maximum capacity, while the worst might only hold as much as a year or two of their stated capacity. It's important to think about how your battery will be used when choosing the right one for your motorhome or travel trailer.

If you’re like most RV users and enjoy having a few appliances plugged in for your convenience while on the road, then you definitely need a decent deep cycle battery powerful enough for your setup.

More than any vehicle, you need to buy an RV deep cycle battery that is very specific to your usage.

Different RV users have wildly differing power needs. Some like it simple with nothing but lights at night. Others want to bring in every conceivable appliance from their house – power consumption be damned!

So it’s essential to know when, where and how you're going to use your RV – and every piece of appliance in it.

As always, research and planning are your best friend. You need to do your homework, or your risk cutting your RV trip a little short.

So what are the essential things to consider when out buying an RV deep cycle battery?

This is probably the #1 factor to consider when getting an RV deep cycle battery. As stated above, how much power you need is directly proportional to the number of onboard appliances you plan on using.

You need an RV deep cycle battery with a large enough capacity, which is measured in Amp Hours or AH. AH tells you how much current (or amps) the battery can deliver over a set period (defined in hours) before it’s fully drained or discharged.

A battery with 100 AH, for example, can power up 10 amps worth of appliances for 10 hours. The higher the power consumed, the faster it discharges. So a 50-amp consumption will only last that same battery 2 hours before being fully discharged (or, mathematically speaking, 50 amps x 2 hours = 100 AH)

However, it's not a good idea to drain your battery down to 0%, or else you risk shortening its life. Manufacturers and experts advise never to let your battery's capacity drop below 20%

So you need to factor this in when choosing a proper AH rating for your RV deep cycle battery. In practice, this means that your usable AH is only 80% (i.e., for a 100 AH battery, your maximum consumption is only at 80 AH) before you need to recharge.

After power consumption, another thing influencing how much AH to get for your RV deep cycle battery is your decision to go off-grid.

Going off-grid simply means operating your RV without connecting to an external power source. Off-grid gives total freedom to some RV user, and more are frequently doing this.

How is this relevant to you?

If you plan to disconnect from any power source for a significant amount of time, you need to make sure you have enough reserve power to last you through. Get an RV deep cycle battery that has the biggest AH rating you can afford. 100-125 AH is a number to target.

On the other hand, if you find yourself having a constant source of power, then you can get away with a much lower AH rating. A minimum of 30-50 AH RV deep cycle battery should suffice.

Dual-purpose batteries combine the best of both worlds – the cranking power of starter batteries and the repeated charge/discharge abilities of a deep cycle battery. But do you need it?

The obvious benefit is cost. In some cases, it’s still cheaper to get a dual-purpose battery than to get a starter and a deep cycle battery each. You also get the benefit of charging while the RV is running, without the need for a power source.

However, keep in mind that the capabilities and amp output of a dual purpose are still far less than that of a dedicated starter or deep cycle battery. If you’re operating a low-consumption rig, then a dual-purpose battery can give cost savings and might be a good idea.

Or you can extend this to “what the weather is like in the area you intend to bring your RV to.” Extreme temperatures can affect your RV deep cycle battery’s performance; so make sure it can operate in the proper range. Cold weather is especially challenging, so make sure your battery is up to par!

While not as tough as an ATV battery, RV deep cycle batteries still need a fair amount of durability and shock resistance. After all, you're taking your RV out in the open, and there's no telling what terrain you'll encounter.

Aim for a spill or leak free construction and shock absorption. This saves you the trouble of messy topping up or repairs, should your batteries get damaged in transit.

There are many different types of RV deep cycle batteries available, but some are better than others.

Traditional lead-acid batteries, or what's called flooded cell, are the most common type and generally the cheapest option. They perform quite well and are more than suitable for an RV. Their major drawback pops up come maintenance time – they need to be regularly topped up with water to ensure proper operation. Forget this, and you're looking at a ruined battery.

If you’d rather not mess around with that, go with maintenance-free lead acid batteries, such as gel or AGM. Of the two, AGMs perform better for use as an RV deep cycle battery. While gel batteries need to be charged at a lower rate and voltage, AGMs are not stopped by such limitations.

For the best performance, you can’t go wrong with lithium-ion batteries. They charge a hell lotta faster, weigh so much lighter and hold much more capacity than lead acids. The thing is, they’re also much more expensive. If you can afford it, go for it.

Lithium batteries degrade over time at a slower rate than lead-acid batteries, so they have a longer life cycle. Unlike lead-acid batteries, lithium batteries will deliver full power even when the cells' energy levels are depleted. They run more electrical equipment in your RV for longer periods of time. A disadvantage of lithium batteries though is a lack of performance in extremely cold temperatures.

Of course, we want them to last forever. But that's not entirely realistic, isn't it? On average, you should expect a battery to last an average of 8-10 years with proper maintenance.

Regularly discharging and recharging it, but not letting it drop below 20% capacity, is key to a battery’s lifespan.

Also, consider the warranty when shopping for a battery. Warranties are important! They are an excellent insurance policy, should you get a battery that doesn't quite work as it should (and it happens quite a lot).

The VMAX SLR125 AGM Deep Cycle Battery should be your top choice if you’re looking for a winning combination of performance, price, and durability.

First impressions definitely last, and our initial opinion when we got the VMAX SLR125 out of the box is how durable it feels. The outer shell is of solid construction, and the plates themselves are made out of military-grade metals. VMAX claims this is a battery that can live for 8-10 years, and we're inclined to believe that assessment.

You’d have no worries taking this out for a spin – rain or shine, hot or cold. It could easily survive a drive down a rugged off-road path. The fact that this deep cycle battery is also made for use in boats is a testament to its toughness.

And did we mention that it’s heavy? This is one hefty 75 lbs RV deep cycle battery. On the one hand, it gives the impression that it has a massive capacity and means business. On the other, it can be a challenge to lift and install. But how often do you need to do that? 

Performance wise, it boasts an impressive capacity of 125 AH, more than enough for a few days off-grid. The VMAX SLR125 is an excellent option if you're looking for a high capacity battery. We hooked it up to our rig setup and handled the almost 90+ AH power drain effortlessly.

Being an AGM battery, it charges pretty fast and is maintenance free, which is a nice bonus.

Overall, the VMAX SLR125 delivers reliable performance and can easily protect itself from the toughest of conditions. The price point isn't bad either, which further makes it a must buy.

For the RV user wanting a hassle-free off-grid experience, few can top the capacity and quality of the Universal UB121000.

At its core, the UB121000 is a hardworking AGM deep cycle battery. It's leak and maintenance-free, so it makes it a joy to use – just set and you’re good to go. Its shock and vibration resistant as well so these can withstand the normal bumpiness from a typical RV ride, maybe more so. 

The UB121000 provides a robust 100 AH capacity, great for powering an RV off-grid with the extra conveniences. We tested it out when we camped out, and it ran our lights and radio for the duration of the weekend. The amazing part is it’s still relatively full!

But probably the great thing about this RV deep cycle battery is it’s such a great deal. It’s a mid-range priced battery that provides high-priced performance. That’s value for money right there!

If you plan on going off-grid and want to invest in a reliable battery that won’t break the bank, get the Universal UB121000. An RV is already expensive as it is – best not deepen that hole in your pocket any further!

The Optima 8052-161 D31M is a fusion of the high cranking power of a starter battery and the charge capacity of an RV deep cycle battery. In other words, it’s a true dual-purpose battery. What this means is that it can both supply the necessary AH to power your appliances, plus a burst of cranking amps when you need to start the engine.

At the heart of the Optima 8052-161 D31M is its unique Spiralcell Technology. Instead of using flat plates, their batteries use two lead plates arranged in a spiral. This translates to more rapid charging, higher power capacity and greater resistance to vibration.

Or in other words, better overall performance and longevity compared to other AGM batteries.

As a starter battery, the Optima 8052-161 is capable of dishing out 900 CCA, more than enough to properly start your RV. Deep cycle wise, it can store and discharge up to 75 AH, making it perfect for RVs with mid-range consumption.

All in all, the Optima 8052-161 is perfect for RV owners who just want to deal with one battery. If your camping out for long periods at a time and use your deep cycle battery more than your starter battery, then this dual-purpose option makes sense.

If you’re in it for the long haul and can afford the price tag, then the Battle Born 100 AH Lithium Iron Phosphate Deep Cycle Battery is the last battery you’ll ever need.

The Battle Born is a step up on virtually every other lead-acid and AGM batteries. Right away you’ll notice that it’s very lightweight (around 29 lbs), or roughly 1/3 the weight of comparable AGM batteries of the same power class.

But if you think to be light means having less power, think again!

Performance wise, this battery is top notch. Where to begin? It discharges a continuous 100 AH, with a powerful 200 AH burst should it need to for higher loads. It also charges incredibly fast, making the most of your charging stops when out in the road.

LiFePO4 batteries can also be safely discharged up to 90% of their total capacity without any lasting damage. This allows you to maximize your battery's capacity fully, unlike lead-acid batteries.

And did we say these things can last you a lifetime? LiFePO4 batteries are built for 3000 charge cycles, 10 times more than the standard lead-acid battery's cycle of only 300. You’re looking at a lifespan of over 20 years at the minimum!

Of course, a powerful battery such as this doesn’t come cheap. However, the extreme performance and ridiculous service life offer a great return on your investment in the long run.

For the most serious RV owners who want a powerful and long-lasting battery (and have some money to burn), then the Battle Born 100 AH LiFePO4 battery is one of the best batteries you can buy.