The best deep cycle battery provides consistent power that's enough to sustain anything from a boat to a solar grid.

These high-power batteries boast many features that outperform traditional batteries. When searching for one, it's best to consider how durable it is. It's reserve capacity and cold cranking amps (this is how much power it can supply within a short period of time). The battery should have a high recharge efficiency and have a long life cycle.

Deep cycle batteries come in different models though some of the best tend to be those with AGM technology and are commonly referred to as AGM batteries. (absorbed glass batteries)

We picked the 5 best deep cycle batteries and outlined factors to consider when buying them.

Best Deep Cycle Batteries

1. Mighty Max Deep Cycle Battery

12V 55Ah Power Boat Pontoon Electric Trolling Motor Deep Cycle Battery - Mighty Max Battery brand...
  • ML55-12 SLA is a 12V 55AH Sealed Lead Acid (SLA) rechargeable maintenance free...
  • Dimensions: 9.02 inches x 5.43 inches x 9.13 inches. Listing is for the Battery...
  • SLA / AGM spill proof battery has a characteristic of high discharge rate, wide...
  • Rechargeable battery that can be mounted in any position, resists shocks and...
  • Backed by a 30 day refund policy and full 1 year warranty

What makes the best deep cycle battery is that it's a 12V 55AH Sealed Lead Acid (SLA) rechargeable, maintenance-free battery. Mighty Max battery will be a perfect choice if you want to power a small to medium trolling motor.

The SLA/AGM battery has a high discharge rate and long service life. The spill-proof battery has a 55Ah amp hour rating and is an environmentally conscious choice that can be stored at any angle in an unventilated battery box.

The Mighty Max battery features a wide operating temperature range, making it an ideal choice for all-year-round use. The deep cycle AGM battery is covered by a one-year warranty.

Pros

  • Long-lasting and durable.
  • Great for trolling motors.
  • Mighty Max battery holds a great charge.
  • Lead-acid battery.
  • Uses AGM Technology.
  • Sealed batteries.

Cons

  • Best suited for small boats.


2. Odyssey Batteries Dual Purpose Battery

Odyssey 31M-PC2150ST-M Trolling Thunder Marine Dual Purpose Battery
  • Cold Crank Amp (CCA)- 1150 Better warranty: Limited 3 and 4 year full...
  • Longer cycle life: 70 percentage longer cycle life compared to conventional deep...
  • Recharge: Highest recharge efficiency of any sealed lead battery on the market,...
  • Vibration resistance-design protects against high impact shock and mechanical...
  • This item is not for sale in Catalina Island

What makes the Odyssey Battery the best deep cycle battery is its dual-purpose nature. The marine battery fulfills both roles of a cranking and deep cycle battery efficiently.

The marine battery offers 1150 CCA, giving it immense cranking power capable of starting any recreational inboard or outboard motor, even in cold weather. The deep cycling capability is quite impressive, lasting for up to 400 cycles at 80 percent depth of discharge.

The deep cycle marine battery has the highest recharge efficiency of any sealed lead battery on the market and is capable of 100 percentage recharge in 4-6 hours. The battery model should ideally deliver 5 amps of current per hour for 20 hours, giving you plenty of time to troll your local lake or river without having to recharge.

The AGM batteries are more resistant to shock and vibration and have a lower self-discharge rate. Due to its AGM design, you don’t have to top it up with distilled water or worry about spilled battery acid as you would with a traditional wet-cell battery.

Pros

  • Has a 70% longer life cycle compared to conventional batteries.
  • Features cold-cranking amps of 1150.
  • Extreme temperature tolerant.
  • Dual-purpose battery.

Cons

  • Quite heavy.
  • The batteries feature a different design from what they had before.


3. Optima Batteries Deep Cycle Battery

Optima OPT8016-103 Batteries D34M BlueTop Starting and Deep Cycle Marine Battery
  • 12-Volt, 750 Cold Cranking Amps, Size: 10 inches x 6 7/8 inches x 7 13/16 inches...
  • Optimal starting power even in bad weather
  • Mountable in virtually any position. Works well as a boat battery or RV battery
  • Fifteen times more resistant to vibration for durability
  • Reserve capacity of 120 minutes for constant performance

The deep cycle battery features a lightweight design; hence it can be mounted in any position. It's durable and works well as a boat battery or RV battery.

The deep cycle marine battery has a reserve capacity of 120 minutes for constant performance. The battery model features 750 Cold Cranking Amps, and the voltage is 12 V.

The Optima battery is fifteen times more resistant to vibration, can withstand bumpy roads, and starts up even when the weather is bad.

Though on the smaller side of other marine batteries, what makes it the best deep cycle battery is its long-lasting, reliable charge. Optima batteries' power output is immense and will provide your RV with hours of electricity.

Pros

  • Affordable.
  • Lightweight battery.
  • Maintenance-free.
  • Vibration resistant.
  • It can be installed in any position.
  • Spill-proof.
  • Uses AGM technology.
  • 120 minutes reserve capacity.

Cons

  • Some reviews noted that they don't fully charge.


4. Trojan T-105 Deep Cycle Flooded Battery

If you use off-grid solar power systems like solar panels, then these RV batteries would be ideal. The deep cycle RV batteries are one of the most reliable choices on the market. The 6V battery requires being purchased as a set of two to charge your RV at 12 volts fully. It's the best deep cycle battery if you're looking for a replacement.

The deep cycle battery is perfect for solar energy storage in households with various large appliances like refrigerators, air conditioners, etc. The RV battery has a 225 Ah capacity, including 125 Ah of usable capacity. Each battery has a lifespan of approximately 1,200 cycles and an excellent durability rating due to the thicker lead plates.

The flooded batteries are covered by an 18-month warranty to cover any defects or immediate issues.

Pros

  • Ideal as a replacement battery.
  • Don't require regular maintenance.
  • The deep cycle batteries can operate in extreme weather.
  • They feature corrosion free terminals.

Cons

  • You need at least two batteries to use them.


5. VMaxTanks AGM Battery

The deep cycle AGM battery is perfect for trolling motors.

The trolling motor AGM battery is ideal for use by small boats and RVs. It has a capacity and can provide for up to 9 hours. The AGM battery uses AGM technology has great resistance against shocks and vibrations. It's also maintenance-free.

Pros

  • Its spill and leak proof.
  • Lightweight battery.
  • Has outstanding power for its size.

Cons

  • Replacement warranty is up to a year.


Factors To Consider When Buying Best Deep Cycle Batteries

a) The Type of Battery

There are three kinds of deep cycle batteries:

i) Flooded Lead Acid

This type of battery is quite popular, whether in Automotive (as starter batteries) or storage (as deep cycle batteries). Its referred to as flooded since the lead plate is submerged in electrolyte fluid (usually, Sulfuric Acid).

When charging, some water is decomposed from the electrolyte. Hence, you must regularly inspect it and check the levels of the electrolyte. If it's below the desired level, you can top-up with distilled water. Charging of the batteries tends to occur in stages; hence there's a possibility of overcharging or undercharging.

ii) AGM Batteries ( Absorbed Glass Mat)

This battery contains a special fiberglass mat that contains an electrolyte solution between batter plates. The electrolyte suspension system has the electrolyte in a dry state.

While the battery is working, the electrolyte moves from the glass mat to the battery plates. The mat contains sufficient electrolytes that are adequate for the cell to deliver its full capacity.

The batteries are also known as Sealed Lead-Acid batteries. No distilled water needs to be added hence they don't require any maintenance. They better vibration and shock resistance in comparison to wet or gel batteries. They also have a faster recharge rate than a lead-acid battery but are not as fast or efficient as lithium-ion batteries.

iii) Gel Batteries

A Gel battery uses a special type of gel made from Silica that holds the electrolyte. Thus, the electrolyte becomes a semi-solid gel-like quantity, making it spill-proof and maintenance-free.

Gel batteries do not release any gasses like flooded lead batteries and do not require any ventilation.

b) Weight and Size

It's key to consider the size and weight of deep cycle marine batteries vis a vis your RV or watercraft. This is because you'll need to run several different applications for extended periods of time.

A lithium-ion deep cycle battery will be lightweight and energy-dense compared to a lead-acid marine battery.

Choosing a lighter and smaller battery affords you more flexibility when considering your application’s total weight and balance.

However, though lithium-ion is smaller and lighter, its high energy efficiency means it performs better than lead-acid at a fraction of the size.

c) Power

To keep everything running, this depends on how much power the battery is putting out. This power is measured in amp-hours, referring to how many amps the battery discharges in a 20-hour period.

Reserve Capacity (RC), on the other hand, refers to how the number of minutes the battery lasts when providing amp output.

Ideally, you want the best marine batteries that can give you more amp hours and RC, allowing you to keep things powered longer. 

d) Depth of Discharge

The depth of discharge (DoD) is another key consideration when searching for the best marine batteries. It is the total amount of energy discharged from the battery and is also expressed as the percentage of the total power capacity of the battery.

When using a marine battery, the more often your discharge and charge it, the greater the chances of reducing its service life span. Hence, it is advisable not to discharge your batteries completely and only use the manufacturer's maximum recommended DOD.

e) Durability

When buying a new battery, durability is always a key concern, as no one wants to buy a replacement too soon. Hence, ensure that the battery model you select is highly durable.

Ideally, the best deep cycle battery should not be affected by repeated deep discharges and charges. Additionally, your battery should be capable of delivering greater performance for high-demand applications like marine, aircraft, and solar energy systems.

Most batteries are vulnerable to various factors like temperature, shock, vibrations, etc. Hence ensure that your marine can withstand these factors without compromising its performance and lifespan.

f) Shelf Life of a Battery

Your battery's shelf life is crucial and is dependent on three factors, the chemicals in the cell, its idle time, and the storage temperature.

Most deep-cycle batteries come with high self-discharge rates. Hence, it's key to note that your battery is at risk of losing its power when idle really fast with a high self-discharge rate.

This tends to be quite difficult, especially in extreme weather conditions, where high temperatures intensify the self-discharge rate, making it inevitable for all batteries.

The ideal shelf life offered by the best deep cycle batteries is around ten years before they start losing the maximum capacity. The shortest shelf is for about a year or two, and this tends to be for marine batteries that are not too great.

Frequently Asked Questions About Deep Cycle Batteries (FAQs)

a) How Long Do Marine Batteries Last?

Marine batteries can last anywhere between two to five years. This is, however, dependent on how well the batteries are maintained. You can extend the marine battery's life by connecting it to a charger when not in use.

b) What Is The Difference Between A Starting Battery and Deep Cycle Battery

A starting battery delivers a large burst of power for the period of time needed for the engine to start. The battery is later recharged by the alternator. They are not designed to withstand multiple discharge/recharge cycles, and draining them can significantly shorten their life.

Deep cycle batteries are generally designed to provide a steady amount of power over a long period of time. They can be repeatedly discharged and recharged without causing damage or shortening their life. These batteries are best suited to powering numerous electronics and plug-in accessories or other applications that place high demands on them, such as marine.

c) How Do You Charge A Marine Battery?

To give your marine batteries that extra boost of more power, it is possible to use battery chargers. It's advisable to start by switching the battery off and removing it from the box. Ensure that you have the right charger for your battery size and connect the charger clips to the battery terminals. Then, switch on the battery, and it should start charging.

Depending on the model, smart battery chargers with LED displays will let you know when your battery is fully charged. When it is, switch it off, disconnect the clips, and place the battery back in its box.

d) Is It Possible To Overcharge a Deep Cycle Marine Battery?

Yes, it's possible to overcharge a deep cycle battery. Overcharging reduces the lifespan and overall capacity of the battery. Hence, it's best to be careful and avoid doing that, especially if you want to prolong the battery's long life.

One way to avoid this is by getting the right charger. Most AGM batteries can usually be charged to a level of 2.4 volts per cell. Depending on your charger, you can lower it. If using a float charger, lower the level to 2.25 volts per cell. If it's hot outside, consider lowering the charging voltage further, as a high temperature allows fast charging of the batteries.

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