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6 Best Deep Cycle Marine Batteries – (Reviews & Guide 2021)

The arrival of the fishing season brings with itself a lot of preparation. You need to check on your boat, equipment, and make sure that everything is in order. The most important thing, besides the overall tools and fishing tackles, is to have your boat ready to take on long days of fishing. Having the best deep cycle marine battery is just the thing that will help you do that.

Having a reliable deep cycle marine battery is essential as it is not only a matter of good performance but is often a matter of safety as well.

As this is a significant device, it requires lots of research, and this is not as easy as it sounds. Our job, however, is helping our readers, that’s why we have made the scrutiny for you. Our buying guide consists of many tips, helpful information, and most importantly reviews on the best deep cycle marine batteries.

Best Deep Cycle Marine Batteries Comparison Chart

Vmaxtanks Solar Deep Cycle Rechargeable Battery

Vmaxtanks Solar Deep Cycle Rechargeable Battery

  • Price: $$$$$
  • Dimensions: 6.8 x 12.9 x 8.7″
  • Weight: 75 pounds
  • Volt: 12 volts
  • Capacity: 260 minutes of reserve capacity
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Mighty Max Battery Deep Cycle AGM Battery

Mighty Max Battery Deep Cycle AGM Battery

  • Price: $
  • Dimensions: 7.68 x 5.16 x 7.13″
  • Weight: 24 pounds
  • Volt: 12 volts
  • Capacity: 35 amp hours 
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Renogy Deep Cycle AGM Battery

Renogy Deep Cycle AGM Battery

  • Price: $$$
  • Dimensions: 13 x 6.8 x 9″
  • Weight: 66 pounds
  • Volt: 12 volts
  • Capacity: 100 amp hours
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Optima 8016 Bluetop Starting And Deep Cycle Marine Battery

Optima 8016 Bluetop Starting And Deep Cycle Marine Battery

  • Price: $$$$$
  • Dimensions: 10 x 6.9 x 7.8″
  • Weight: 43.5 pounds
  • Volt: 12 volts
  • Capacity: 120 minutes of reserve capacity
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Interstate Batteries Sealed Lead Acid Replacement Battery

Interstate Batteries Sealed Lead Acid Replacement Battery

  • Price: $$
  • Dimensions: 7.7 x 5.2 x 6.3″
  • Weight: 23.8 pounds
  • Volt: 12 volts
  • Capacity: 35 amp hours
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Optima 34M Bluetop Marine Starting Battery

Optima 34M Bluetop Marine Starting Battery

  • Price: $$$$
  • Dimensions: 10 x 6.9 x 7.8″
  • Weight: 38.4 pounds
  • Volt: 12 volts
  • Capacity: 100 minutes of reserve capacity
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1. Vmaxtanks Solar Deep Cycle Rechargeable Battery

Vmaxtanks Solar Deep Cycle Rechargeable BatteryIf you are looking for a marine battery to be used with PV solar panels or inverters, Vmaxtanks deep cycle battery is one great option with a life span of 8 to 10 years in float mode. It packs a lot of power delivering 125 amp hours on a 12-volt battery. This battery will be the ideal choice for powering your boat for lights and a few appliances.

The battery is built with military-grade custom made plates to ensure high performance and long life span. Being an AGM sealed battery, it is maintenance-free and gives you flexible mounting options. Moreover, it has the benefit of recharging quickly. The battery is quite durable as it can withstand the impact of excessive vibration and shocks.

There is an option to acquire an additional battery calculator. It will be useful in determining the number of batteries needed for your specific AC or DC power requirements.


  • 12 months warranty
  • 8 to 10 years service life span in float mode
  • Build with military-grade custom made plates


  • Quite heavy weighing 77 pounds
  • Liable to overcharge which will cut the service life span

2. Mighty Max Battery Deep Cycle AGM Battery

Mighty Max Battery Deep Cycle AGM BatteryBacked by a 30-day return policy and a full 1-year warranty, Mighty Max showcases a 12 Volt AGM marine battery with 35 amp hours capacity. This AGM deep cycle battery is pretty compact measuring just 7.68 by 5.16 by 7.13 inches and weighs only 23.5 pounds. Because of its light-weight, it is a popular choice for powering small boats. However, they are being used in a range of applications starting from consumer electronics to portable tools. The handle design makes it easy to carry around.

This is an AGM sealed battery and requires no maintenance. Moreover, it gives you the freedom to mount the battery anywhere that suits your surroundings without fear of leakage. It is able to resist shocks and vibration. The battery can withstand both low and high temperatures making it a great choice as a marine battery.

The ML-35-12 uses a calcium-alloy grid to store more energy and boosts its performance for a longer time. Having said that, it is worth noting that once the battery is drained, it takes time to recharge.


  • High discharge rate
  • Ideal for boats due to the compact design
  • One-year warranty


  • Takes time to recharge
  • Minimal amp rate

3. Renogy Deep Cycle AGM Battery

Renogy Deep Cycle AGM BatteryIf you are looking for a battery to store solar energy, you have hit the right spot. Renogy brings you a special marine battery intended for solar energy storage applications. It is a deep cycle AGM battery which is an excellent choice for off-grid application as backup power for a boat. However, with the right battery, it can be an ideal choice for daily use too. Bear in mind, the battery will need a special charger unless you are using a smart charger.

The product is rated deep cycle AGM battery and thus comes with the typical features of AGM batteries such as leak-proof, spill-proof and maintenance-free. It is also shocks and vibration resistant which will result in higher durability.

The manufacturer recommends avoiding over-discharging batteries, especially when they are in series or parallel connection for a longer life span. It should be discharged to a maximum of 50%. The battery packs a lot of power and has a capacity of 100 amp-hours.


  • Two- year warranty
  • High capacity 100 Ah marine battery
  • Sealed, maintenance-free operation


  • Even though it is spill-proof and leak-proof, mounting is difficult due to its heavy weight
  • Requires a special charger

4. Optima 8016 Bluetop Starting And Deep Cycle Marine Battery

Optima 8016 Bluetop Starting And Deep Cycle Marine BatteryOptima brings you the ultimate power source for boats and RV with heavy electrical accessories.  The 12-Volt deep cycle marine battery with 750 cold-cranking amps is a popular choice for boat owners and capable of up to 3 times more recharges than any other marine batteries. It can be mounted in almost any position as it is spill-proof.

The Bluetop Optima 8016 has a dual purpose, meaning it serves both deep cycle application and the starting application. It is maintenance-free and works well even in harsh weather. The unique spiral-cell technology ensures not only clean power source but also efficiency, high output and long running time. Moreover, it is 15 times more resistant to vibration making it extra durable.

Another great feature of this battery is that it has a reserve capacity of 120 minutes which gives you an ample amount of time to recharge it before reducing its amps to a minimal level.


  • Optimal starting power even in harsh weather
  • Highly durable as it is 15 times more resistant to vibration
  • Reserve capacity of 120 minutes
  • 99% pure lead plates for more energy storage


  • Very heavy
  • Risk of overcharging

5. Interstate Batteries Sealed Lead Acid Replacement Battery

Interstate Batteries Sealed Lead Acid Replacement BatteryThis is a universal 12-Volt marine battery which has a capacity of 35 amp-hours that can be used for a wide variety of applications such as consumer electronics, electric vehicles, power sports, portable tools, medical mobility, lawn and garden tools to name a few. But mostly used by boat owners because it is small and lightweight and will not add a significant weight on the boat.

A product of Interstate Batteries, this deep cycle battery requires no maintenance as it is a sealed lead acid-SLA battery. This also means that there will be no room for leakage and hence gives you great options for mounting in any position.

Like any deep cycle battery, it has a decent long-running service life but needs an ample amount of time to recharge fully once it is drained. Full recharging can take up to 12 hours or more.

Another advantage is that the battery can resist vibration and shocks. This will result in increasing the longevity of the cell.


  • Modest size and lightweight makes it an excellent choice
  • Maintenance-free
  • Resists vibration


  • Takes too long to recharge
  • Not powerful enough for a golf cart

6. Optima 34M Bluetop Marine Starting Battery

Optima 34M Bluetop Marine Starting BatteryOptima has specially produced a battery that is designed to be used as a starting battery. It is a 12-Volt marine battery with 800 cold-cranking amps that can start an engine even in extreme weather conditions. It is worth noting for boat owners that this battery has a blue top and a dark grey case and it is intended to be used when a dedicated starting battery is required and should never be used as deep cycling application unlike the other Optima blue top with a light grey case.

The battery has a reserve capacity of 100 minutes for consistent performance and long running time. It boasts having 3 times more recharges than other marine batteries. With no maintenance required, you can mount the battery in almost any position as it is sealed and resists against vibration.

The patented spiral cell technology is environmentally friendly and ensures safe usage. It also gives you the advantage of higher reserve capacity resulting in longer shelf-life.


  • Highly durable as it is 15 times more resistant to vibration and shocks
  • Excellent for starting application even in harsh conditions.
  • Environmentally friendly


  • Cannot be used for deep cycle application
  • Not compatible with all types of chargers

What is a Deep Cycle Marine Battery?

Best Deep Cycle Marine BatteryWhen it comes to marine supplies and appliances you surely have a variety of options available on the market. Finding a suitable marine battery, however, may become a difficulty as they are many products to choose from but also many unreliable units. For this, it is necessary to know what to look for, and luckily for you, we have gathered all pieces of information you need in one place.

To understand what exactly a deep cycle battery is, how it works and what it does, we need to start with marine batteries in general, and their three basic types: Cranking/Starting Marine Battery, Dual Purpose Marine Battery, and the subject of our article – Power/Deep Cycle Marine Battery. Let’s have a closer look at the deep cycle marine batteries, as they are the type that we are actually interested in, and then say a few words for the other two types.

  • Power/ Deep Cycle Marine Batteries

We could say that these batteries are the equivalent of ‘marathon runners.’ A deep-cycle battery is a device meant to be routinely discharged all the way down. The majority of deep cycle batteries on the market nowadays are lead-acid batteries. It is important to remember that the number of discharge and charge cycles a battery can perform and the depth of discharge (DOD) are inversely proportional. A depth of discharge that is around 50% is considered to be the most optimal choice when it comes to expenses and storage.

Unlike cranking marine batteries, power/ deep cycle marine batteries are perfect for providing power to electronics and appliances, without the risk of overheating. For this reason, these are the types of cells that we are most familiar with.

The lead battery plates are what sets the deep-cycle batteries from the cranking ones. Deep cycle plates have separators and their active plates are also thicker. The plates of a deep-cycle battery are made of alloys that have more antimony compared to that of cranking batteries. For this reason, this type of cells resists corrosion through extended discharge and charge cycles.

Nowadays, newer technologies, such as lithium-ion batteries are getting more and more common in this same form factor. However, they are too expensive.

  • Cranking/Starting Marine Batteries

If we continue with our comparison, while the deep cycle marine batteries were the marathon runners in our contest, the starting marine cells can be referred to as the ‘sprinters.’ They will not provide a steady, consistent stream of power. On the contrary, for a brief period, these devices give you a high power discharge to get your engine started, and then they turn over the powering duties to an alternator.

As starting marine batteries are vulnerable to overheating they cannot be used to provide a reliable source of power to appliances. Their primary purpose is to ignite the motor of your boat and to regularly make sure that you can navigate and go slow or full throttle.

  • Dual Purpose Marine Batteries

As their name hints, these ‘players’ know both how to sprint and how to run a long distance. In other words, a dual purpose marine battery is a hybrid that can provide a boost of power to crank, start your engine and at the same time provide a steady stream of energy to your appliances.

Now we know this sounds great, but we are sure you have heard the old saying ‘To do two things at once is to do neither.’ This is precisely the case with dual purpose marine batteries- they can do neither of the tasks mentioned above exceptionally well. Their lifespan is also not as long as the one of an actual deep cycle battery.

Benefits of Using a Deep Cycle Marine Battery

Benefits of Deep Cycle Marine BatteryThese batteries have a lot to offer, and that is precisely the reason why so many people choose them. Here is a list of their main advantages:

  • Deep Cycle Marine Batteries can be discharged down to 80 percent (deep cycled) without causing damage.
  • They provide power to electronics and appliances.
  • Low risk of overheating.
  • They have solid lead plates.
  • Long lifespan.
  • There is a wide range of applications:

–    Cathodic protection (might include marine usage)

–    Other underwater usages, especially on sailboats that lack power. (generally smaller vessels)

–    Fishing boats with trolling motors

–    Industrial machinery that is electrically-propelled

–    Energy storage schemes for wind or polar power

–    Power for equipment and instruments, and more.

Drawbacks of Using a Deep Cycle Marine Battery

When you choose a product it is essential to know its weak sides as well, so let’s have a look:

  • Heavier than Starting Marine Batteries.
  • Deep Cycle Marine Batteries require regular maintenance and depending on the type of battery you choose you will need to do different things. For example, if you decide on a flooded battery, you will need to provide distilled water every time you refill it.
  • Many of the batteries can be permanently damaged by incorrect charging, so there is no place for mistakes with such devices.

Battery Composition Types

Generally, deep-cycle marine batteries fall into two major categories: FLA (flooded) and VRLA (valve-regulated lead-acid). However, the VRLA category is further subdivided into two types- Gel batteries and AGM (Absorbed Glass Mat batteries).

  • Flooded Batteries

It is not that hard to understand what a flooded battery is and how exactly it works. These batteries contain a quantity of electrolyte fluid that makes sure that the plates are entirely submerged. That’s also why their name is ‘flooded’ batteries. The electrolyte level has to be above the tops of plates. That means that such cells require regular addition of water and inspection of the electrolyte level.

Flooded batteries are really popular as their lifespan could extend beyond 1,000 deep cycles, with the proper maintenance, of course. Of all composition types, their up-front cost is also the least prohibitive. However, as we already said, the interior of the battery is accessible to the elements, and therefore such cells require constant upkeep.

Another disadvantage of using flooded batteries is the fact that they do not handle vibrations well. That restricts the places they can be used since leakage of the acid cell is really dangerous. Such units also require a proper ventilation for they emit hydrogen gas.

Keep in mind that although flooded batteries are the most cost-efficient option at the outset, they will undoubtedly increase the overall investment required for operations, as each time you refill them you need to provide distilled water.

  • Gelled Batteries

Gelled batteries have a lot in common with the flooded ones. However, as they are not filled with liquid, they have far fewer restrictions. When composed properly, a gel battery offers exceptional resistance to vibration.

Such batteries are also very durable. They can be saved away for long periods without being charged since they have a self-discharge rate of roughly 1% per month. Their most significant pro is that they are sealed and maintenance-free.

However, as with any other thing in our life, gelled batteries also have some disadvantages. They are indeed very few. One of them is the fact that you can’t investigate the inside of the cell and therefore you can never know if the liquid gels properly. This can be really dangerous, especially if we talk about lower-quality Gelled batteries.

The second drawback that is worth mentioning is the special charger many Gelled Marine Batteries require. This means that even if you already have a marine battery charger to die for, you may need to buy a new one – so check out our article about it. The reason for this is that they need to be charged at a much lower voltage than the average marine battery. In addition to the fact, the unit itself costs more, gelled batteries are definitely not for everyone.

  • Absorbed Glass Mat (AGM)

Many people believe that AGMs are the future of Marine Batteries. Absorbed Glass Mat Batteries are also called Sealed Lead Acid (SLA) Batteries. They boast a unique technological backbone as they use electrolyte absorbed mats which allow hydrogen and oxygen to combine in a manner that creates its own water. The result is a battery that can be placed pretty much anywhere, regardless of mounting angle and vibrations.

AGMs are also convenient when it comes to maintenance. However, they might not be a good option when weight restrictions are a consideration as they are much more massive than their counterparts. These batteries have a self-discharge rate of about 3% per month, so their lifespan is not as long as the one of Gelled Marine Batteries.

Their most significant disadvantage is the fact that they are vulnerable to being rendered completely defective should they accidentally be overcharged. Still, despite the risk these units carry, most of the popular batteries on the market nowadays are of the Absorbed Glass Mat variety.

Important Battery Ratings to Look For

Deep Cycle Marine Battery ReviewsTo understand the different ways deep cycle marine batteries can be rated and compared, we have gathered the four most common indicators:

  • Amp-hours

This is the first number most people look for. Amp-hours (Ah) expresses the total amount of chemical energy your battery will be able to store and release as electricity. Simply put, Amp-hours show the length of time your battery will operate before recharging is required. The formula by which Amp-hours work is 20 x (amps per hour). So, for example, if your battery has a 150 Ah, that means it will be able to generate 7.5 amps per hour.

Our advice to you is always to overestimate the Amp Hour rating requirement. This is because a battery is never guaranteed to discharge its entire amperage each cycle.

  • Voltage

The Voltage indicates the electromotive power/ force of the current that is supplied by the battery.  When replacing batteries, it is essential to ensure the voltage is correct.

Marine Batteries can be found in 12, 18, or 24 volts. 12-volt batteries are perfect for small vessels with lightweight outboard motors and these products have also been covered by our team in a separate piece. Larger boats that have plenty of space might be better suited for 18 or 24-volt batteries. However, they can also be operated with a bank of 12V units.

  • Marine Cranking Amps

This is the crucial metric for cranking batteries. MCA is the amount of amperage that is generated when starting the engine, in 32 degrees Fahrenheit conditions.

It is essential that before you buy a battery, you go check the recommended MCA of the engine with which you plan to use the battery. Then, choose a battery with a higher MCA rating as it is better to have a bit more amperage than you actually need. However, be careful! If you are starting a small engine, you don’t need a battery strong enough for a freighter.

  • Cold Cranking Amps

The climate in which you plan to use your battery is an essential factor. If you live in a tropical environment or somewhere that is rarely too cold, CCA, or Cold Cranking Amps, is not so outstanding. However, when it comes to more freezing temperatures, you have to look for a battery that has a CCA rating of at least 500.

The CCA rating is defined as the amount of amperage your battery will provide to maintain around 7.2 volts for 30 seconds at 0 degrees Fahrenheit. CCA rating of 500 would be good enough to sustain 10 volts over these 30 seconds.

  • Reserve Capacity

When shopping for a Deep Cycle Marine Battery, this is the most significant metric. RC is defined as the number of minutes your battery requires to discharge 10.5 volts by 25 amps. Therefore, the higher the RC of the cell, the longer it will be able to charge your appliances and electronics.

We recommend that you look for a Deep Cycle Marine Battery that has an RC in the range of 60-120 minutes. The most reliable Deep Cycle Marine Batteries, however, will have a rating of 180+.

Factors to Consider When Choosing a Deep Cycle Marine Battery

  • Battery Ratings

As this is something we already discussed, we won’t get into details again. Just remember that when shopping for a Deep Cycle Marine Battery the two most essential battery ratings are reserve capacity and ampere-hour rating.

  • Size

It is essential to be sure that your battery can fit in the available space. There are different battery sizes, such as 27, 31, 6D, and more. The size of the cell is also closely connected to the output and the power holding capacity.

  • Weight

Now we all know that weight is a byproduct of how large the battery is. However, it is still something you need to consider because if you want, for example, to minimize weight for efficiency and speed, you will have to get a single battery, and not one of the Absorbed Glass Mat kind. 

  • Date of Manufacture

Now, this is essential, especially if you decide to get yourself a second-hand battery. Over time, cells start to lose their effectiveness and are no longer able to maintain the same charge as they once could. Even if your battery is unused and new, if it is one-year-old, for example, it will not perform as well as one that has just been delivered from the factory.

Therefore, it is imperative to check the manufacturing date of the battery. Units which are less than six months old would offer reliable performance, with little or even no loss of starting power or reserve capacity.

  • Maintenance and Design

The design you choose will determine the maintenance of your product. Older lead-acid batteries are a nuisance to own as they require regular maintenance. Newer cells, such as absorbed glass matt ones require zero maintenance, and many people prefer them.

  • Special Functions

Some batteries can be installed in any position. Others are water-proof or can be inverted upside down. These are all features that could be very useful for the marine field. Many deep cycle batteries come with thicker plates so that they could tolerate deeper cycles. When choosing a product, always look for these particular functions as they could really make your life so much easier.

Battery Maintenance

Maintaining your deep cycle marine battery the right way is essential. Here are some simple tips you can follow to extend the life of your battery to its maximum:

  • You must not discharge your battery to below 20% capacity too often, as recharging a flat battery generates accelerated sulfation and heat and therefore, damages the electrodes. Nowadays, many cells have automatic cut-off switches to prevent excessive discharging.
  • Remember that batteries left in storage will slowly self-discharge. If you want to prevent them from going completely flat and get damaged, you will need to give them an occasional top-up. Some batteries have a low self-discharge rate, which means that they could be safely stored up for a more extended period without charging. However, most of the cells will need topping-up more often.
  • You need to charge your lead-acid batteries correctly. Overcharging or charging too quickly might cause an acid leak, hydrogen fire, short-circuit, and even a battery-case explosion. Using a smart digital float charger that has an electric current and temperature regulation is always a good idea.
  • Keep your battery and cable connections clean. Dirty connections are the main reason for many battery problems.
  • The fact that the gases from the battery that condense on metal parts are the main reason for most corrosion is unknown to many people. To prevent cable corrosion on top-post batteries, follow these steps:
  1. At the base of the post, use a little silicone sealer.
  2. Place a battery washer over the sealer.
  3. Use high-temperature oil or even Vaseline (petroleum jelly) to coat the washer.
  4. Having done that, place the cable on the post and fasten it.
  5. The last step is to smear the cable visible end with some grease.

 Safety Tips:

  • Do not add new electrolyte.
  • Do not use an unregulated high output battery charger.
  • Do not detach the battery cables when the engine is operational.
  • Do not put off recharging your battery.
  • Do not add tap water.
  • You should not discharge a battery any more profound than you actually have to.
  • If your battery is way too hot while charging- something is not okay.
  • Regular maintenance and inspection is a must, especially in hot weather.
  • A good rule of thumb is to recharge your battery immediately after discharge.
  • Look for batteries with the highest RC and Ah measures to fit your configuration.
  • If you purchase a used boat, always change the battery!

Installing Your Deep Cycle Marine Battery

If you don’t know how to install your battery just follow these simple steps:

  • Switch your old marine battery switch to ‘off.’ Disconnect the cables, starting with the negative one. Gently lift the battery and remove it.
  • Make sure that the terminals of your new battery are lined up with the cables. Put your new battery into the battery compartment or box.
  • Before attaching the cables, apply a small amount of Vaseline to each terminal. This way you will ensure a robust and reliable connection.
  • Reconnect the cables, starting with the positive terminal. Use a wrench to make sure that the wires are firmly attached to the terminals.
  • Place the lid back on the battery box.

When Should You Replace Your Battery?

Your battery will not last forever, even with the proper maintenance. Therefore, it is essential to know when it’s time for a replacement. If you see any of the signs below, then it may be time to go shopping.

  • You have to jumpstart your battery.
  • Your battery finds it really difficult to turn the starter over.
  • The electronics and lighting dim or go out while starting.
  • Your battery finds it hard to hold a charge.
  • Your battery is submerged.
  • Your battery discharges too often between uses.

Wrap Up

Well done! You have successfully finished our buying guide on finding the best deep cycle marine battery. Having read our reviews on the best deep cycle marine batteries and our additional information and tips, you now realize that finding a reliable product can be a bit hard.

We hope that with this article, we have stirred you in the right direction and you have found a product that will fully satisfy your needs. If that is indeed true, don’t forget to show this piece to others because they might also find it helpful. If there is anything, you would like to tell us, feel free to pop us an email or just write down a comment in the comment section.

If you enjoyed this article, you would be pleased to know that we have many other pieces devoted to finding the most reliable product. Go check them out! Thanks for reading, and as always- stay put!

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