Top 10 Best Deep Cycle Marine Battery Reviews 2021

Don’t be fooled—not all batteries are created equal. At first glance, a deep cycle marine battery looks very similar to any battery you would use for your standard automotive vehicle, but it is far from it. The internal elements of a deep cycle marine battery are significantly different than their automotive counterparts.

While all batteries store energy, there are massive differences in how each type works. And, knowing every battery type is super useful in understanding which ones are most effective for each kind of device or application.

So, if you’re currently in the market for a deep cycle marine battery for your boat, you’ve come to the right place. This guide will list some of the best ones currently on the market, breakdown the different types available, and provide you with some information on setup, maintenance, and tips to get the most out of your marine battery once you purchase and install it.


Why It Is Important To Look For A Deep Cycle Battery

Let’s start with what distinguishes the deep cycle battery from a starting or dual-purpose battery.

The design of a starting battery (aka a cranking battery) makes it omit a lot of energy upon initial start-up and then run for shorter periods. It is best to use in automotive engines or outboard marine engines (engines affixed to the exterior of a boat).

In contrast to the starting battery, the deep cycle battery will discharge less energy upon initial start-up and then run a smaller amount of energy consistently over a more extended period. Because of its energy output design, the deep cycle battery is ideal for motors that require steady, consistent flows of energy rather than large bursts.

These batteries are mostly for use in appliances and motors that require this type of energy output. When it comes to marine vehicles, engines that require the operation of a propeller, or have more substantial and powerful trolling functions, work best with a deep cycle battery.

Lastly, there are dual purpose batteries. These are capable of combining the power of the two types. However, if you plan to use the battery exclusively for a specific kind of boat, then one designed for deep cycle is your best bet to get the most out of battery performance over time.

Our Top 10 Picks For Best Deep Cycle Marine Battery In 2020

Now that we’ve taken a look at what characterizes a deep cycle battery, let’s look at the best ones currently on the market for marine vehicles.

These are some of the top picks based on testing, user reviews, and overall performance:

Optima 8016-103 D34M BlueTop Starting And Deep Cycle Marine Battery

OPTIMA Batteries OPT8016-103 D34M BlueTop Starting and...
  • 12-Volt, 750 Cold Cranking Amps, Size: 10 inches x 6 7/8 inches x 7 13/16 inches tall, Weight: 43.5 pounds, Dual SAE & 5/16 inches Stainless Steel Stud Posts. 55 Ah C20 capacity
  • Optimal starting power even in bad weather
  • Mountable in virtually any position. Works well as a boat battery or RV battery

The Optima BlueTop is a high-performance absorbed glass matte (AGM) battery that is a genuine deep cycling battery with very high cranking power. It is ideal for trolling motors, marine vehicles, and RVs; vehicles where engine starting is the primary function of the battery. It is one of the most sophisticated lead-acid batteries and makes the top of this list because of its ability to outperform all other batteries in its class.

The Optima BlueTop offers users up to three times more recharges and up to 15 times the vibration resistance power when compared to its top competitors. It can be mounted in any position, making it easy to install.


  • High power density
  • Rapid rechargeability
  • Little or no maintenance to get a healthy lifespan out of it
  • Consistent voltage under load
  • Increased vibration resistance for better lifespan



  • Lightweight, great for removal and installation on seasonal vehicles
  • Excellent starting power, even in severe weather conditions
  • Variety of possible mounting positions
  • 15 times more resistant to vibration for enhanced durability
  • 24-month replacement warranty


  • Limited to up to four hours of continuous trolling with standard 12V boat engines

VMAX V35-857 Marine Deep Cycle Battery

VMAX857 AGM Battery 12 Volt 35AH Marine Deep Cycle HI...
  • Dimensions: L=7.7 inch W=5 inch H=6.1 inch
  • Heavy Duty Grids: VMAX heavy duty lead tin alloys provide an extra margin of performance and service life in either float or cyclic applications, even after repeated over discharges.
  • Maintenance Free Operation: There is no need to check specific gravity of the electrolyte or add water to VMAX tanks during float service life. In fact, there is no provision for this type of maintenance.

The VMAX V35-857 is a quality option at a lower price point compared to many of its competitors. It is an AGM battery that is controlled by a smart microprocessor and is ideal for use on vehicles that have trolling motors. At just 25 pounds, the VMAX857 is on the small side for a marine deep cycle battery, making it easy to install, remove, and transport as needed.


  • 12V with 35AH rating
  • Lightweight, great for removal and installation on seasonal vehicles
  • 75-minute reserve capacity
  • Plates are custom-built military alloys
  • Resistant to high vibration, heat, and weather conditions


  • Heavy-duty grids provide extra performance and service life
  • Low-maintenance; checking gravity of electrolyte and adding water are not required
  • Four to five hours of running time with 50%-60% depth of discharge on trolling vehicles
  • Weatherproof, no operating temperature limit
  • Eight- to ten-year lifespan with proper maintenance


  • Only suitable for 18- to 35-pound trolling motors—anything more significant causes it to lose power

Mighty Max Battery For Light Trolling Motors

Mighty Max Battery 12V 35AH Replacement Battery...
  • ML35-12 SLA is a 12V 35AH Sealed Lead Acid (SLA) rechargeable maintenance free battery - UL Certified
  • Dimensions: 7.76 inches x 5.12 inches x 7.01 inches. Listing is for the Battery and Screws only. No wire harness or mounting accessories included.
  • SLA / AGM spill proof battery has a characteristic of high discharge rate, wide operating temperatures, long service life and deep discharge recover.

Explicitly designed for 30H trolling motors, the Mighty Max MLS 100-12 SLA is a compact AGM battery that has screw-in terminals, which means there is no need for mounting accessories. The glass matt technology design means no regular maintenance is required. It is spill-proof, it charges at a high rate, and mounting positions are flexible. It operates smoothly in all temperatures and usually has a lifespan on the higher end for a battery in its class.


  • Absorbed glass matt technology means no maintenance
  • Mountable in any position without worry of spillage
  • Long service life


  • Full one-year warranty
  • Operates well in all temperatures
  • Excellent performance in float and cyclic application


  • Heavy compared to other batteries in its class

Universal Power Group 12V 100Ah Battery

Universal Power Group UB121000 45978 12V 100Ah Sealed...
  • This is an AJC Brand Replacement for a Universal Power Group UB121000 45978 12V 100Ah Sealed Lead Acid Battery
  • Voltage: 12V (12 Volts)
  • Capacity: 100Ah

The Universal Power Group 12V 100Ah is an AGM deep cycle battery than provides a consistent energy source to trolling motors. It is highly efficient, discharging only around three percent of its full capacity every month. The AGM technology also keeps this battery low-maintenance by eliminating the necessity of adding water. The Universal Power Group deep cycle battery has a large storage capacity and boasts an excellent lifespan when compared to others in its class.


  • Charges to 10 amps in 12 hours
  • The wide, acid resistant plastic body makes it leakproof
  • Operates well in standard weather conditions
  • Battery discharges less than three percent of total charge monthly


  • Full one-year warranty
  • AGM technology eliminates the need for regular maintenance
  • Faster charge time than many competitors; more extended usage periods for each charge


  • Heavier than other batteries in its class (64 pounds)
  • Built for average weather conditions (extreme weather can impact operation)

ExpertPower Rechargeable Deep Cycle Battery

ExpertPower 12v 33ah Rechargeable Deep Cycle Battery...
  • Genuine ExpertPower Battery - The Most Trusted And Highest Reviewed Sealed Lead Acid Batteries On Amazon
  • Battery Type - 12 Volt 33Amp/10 Hour Sealed Lead Acid Battery
  • Quality Assurance - Crafted Wtih A Rugged Construction, Our SLA Batteries Are Ultra Durable And Utilize Absorbed Glass Mat (AGM) Technology Which Provides A Wide Temperature Range.

ExpertPower is a brand known for its lead-acid batteries. Their rechargeable deep cycle battery is ideal for use in trolling motors and uses AGM technology, which makes it maintenance-free and allows it to operate well under pretty much any weather conditions.


  • 12V 33Ah high-quality deep cycle
  • Meets ISO standards for quality and safety
  • Lightweight (23.2 pounds)
  • AGM technology allows for functioning in all weather conditions


  • 90-day money-back guarantee; one-year replacement warranty
  • Lightweight, great for removal and install on seasonal vehicles
  • Great brand, known for quality products


  • Usually comes sold in packs of two; most customers generally only need one unit

UpStart Wilderness Tarpon 100 12V 35Ah Battery

Replacement for Wilderness Tarpon 100 Kayak Electric...
  • Replacement Wilderness Tarpon 100 Kayak Electric Trolling Motor Battery
  • Replacement for UB12350 Universal Sealed Lead Acid Batteries
  • One Year Warranty

The UpStart Wilderness Tarpon 100 is a lightweight AGM deep cycle battery that is compact and ideal for use on trolling motors. There are conflicting sources online, which state that the warranty on this model is either one- or two-year. You may want to contact the manufacturer on this if you’re considering this battery. However, a two-year warranty would make it a good buy for anyone looking for the added coverage.


  • AGM technology makes it leak-free and ensures that it holds up in all weather conditions
  • Stable power delivery
  • L1 terminal for screwing to your trolling motor
  • Maintenance-free design


  • Two-year warranty
  • AGM design for leak-free usage
  • Easy installation
  • Lightweight (under 30 pounds)
  • Lasts up to four hours per ride


  • Not enough user information available; still a relatively new product

PowerStar Deep Cycle 12V 55Ah Battery

12V 55Ah Power Boat Pontoon Electric Trolling Motor...
  • AGM12-55 SLA is a 12V 55AH Sealed Lead Acid AGM/SLA rechargeable True Deep Cycle - UL Certified - 2 Year Free Replacement Warranty
  • Dimensions: 8.98 inches x 5.43 inches x 8.98 inches. Listing is for the Battery and Screws only. No wire harness or mounting accessories included
  • Replaces: CA12550, GH12480, EDS12500, NP55R12HD, BAT-12550, PS-12550, PS-12600, ALA1160, RB12550, DM5512, 22NFSLDG, WCG22, PRB1255, PC1200, PC12620, PS12550NB, PC12620, PS12550NB, SLA55-12, S12500, 0889566000, a212/55A, M84001A5120550A, 22NF, TR50-12A, TR55-12, 6GFM55, UB12500, UB12550, EXP12500, NP12-55, ML55-12INT, TL1255/FP12550, SP12-55, Elite HD, PSV 12550, WKDC12-55P

Boasting a three-year warranty when used on float devices; and a two-year warranty on all other devices, the PowerStar Deep Cycle battery is an excellent choice for anyone looking for the added peace of mind. It does, however, come with a price-tag that reflects this. This battery also weighs in on the heavier side at 38 pounds (many of its lighter-weight competitors are under 30 pounds). Like other options on this list, the PowerStar Deep Cycle battery has an AGM design, making it a no-maintenance battery, which provides extra protection against leaks.


  • AGM technology; no leaks, no maintenance
  • 38 pounds
  • Designed specifically for marine use
  • 12V 55Ah marine battery


  • Three-year warranty on float devices; two-year on all other motors
  • PowerStar’s unique sealing technique protects against terminal leakage
  • Close to double the power of a standard 30Ah battery


  • Heavy (38 pounds)
  • Minimal user reviews
  • Can be challenging to install and use
  • Short service life

Interstate Sealed Lead Acid Deep Cycle Battery

Interstate Batteries 12V 35AH Sealed Lead Acid (SLA)...
  • DEEP CYCLE MOBILITY BATTERY: Interstate Batteries DCM0035 professional-grade, high-quality battery developed specifically for electric wheelchair's, electric scooter's and more. Longer life & more cycles for deep discharge usage – Interstate’s DCM batteries rated as the best performer for heavy-demand deep-cycle batteries, making them Outrageously Dependable
  • RECHARGEABLE, MAINTENANCE-FREE, SPILL-PROOF: Rechargeable, maintenance-free, & spill-proof because of the AGM & VRLA technology (valve regulated) that eliminates spills & overpressure. 12 Volt, 35 Amp hours. 7.68” x 5.16” x 6.42” (LxWxH). Industry size Group U1 or GT9L. Insert terminal with bolt, replaces FLAG TY. This battery is not a replacement for Golf Cart batteries

This battery is a good option for use on small trolling motors. The Interstate sealed lead-acid deep cycle battery is compact and offers quality performance for smaller marine vehicles with trolling engines. It is lightweight and super easy to mount in any boat. Because of the AGM design, dealing with maintenance or leakage is not an issue.

At a much lower price point than some of the bigger deep cycle variants, the Interstate is a good bet for anyone looking for a compact option to power a smaller motor.


  • Lighter than most other batteries (23 pounds)
  • AGM technology; no leaks, no maintenance
  • A plastic casing that is strong against any external elements


  • Portable and compact
  • Comes with carrying strap for easy transport
  • An inexpensive option for anyone who doesn’t need a ton of capacity


  • Only suitable for smaller vessels
  • If overcharged, lasting damage can occur to the battery

Carmanah CMH AGM 100 Amp Deep Cycle Battery

Go Power! CMH-AGM-100 12V 100 Amp AGM Deep Cycle...
  • Great for Marine, RV, Fleet, Off Grid applications
  • 110 Amp Hour At 100 Hour Rate
  • Maintenance Free and Spill Proof

The Carmanah CMH model comes equipped with an AGM design ensuring it is maintenance-free and spill-proof. A built-in handle makes it easy to transport, and it is the ideal choice for trolling motors that require higher power demands. It is an easy-to-install battery and a great option for marine vessels. It can withstand extreme weather conditions, and its design gives it the ability to hold up to substantial power requirements.


  • 6 pounds; heavyweight for heavy-duty demands
  • 100 amp/hr at 100 hr rate
  • Built-in carrying handle
  • AGM technology; no leaks, no maintenance


  • Two-year warranty
  • Great for bigger trolling engines that require more power
  • Easy to install


  • It is one of the heaviest options at 67.6 pounds
  • Price is high, but you pay for the power

Odyssey 31M-PC2150ST Trolling Thunder Marine Dual-Purpose Battery

Odyssey 31M-PC2150ST-M Trolling Thunder Marine Dual...
  • Cold Crank Amp (CCA)- 1150. Better warranty: Limited 3 and 4 year full replacement warranty: not pro rata; Longer service life: 3-10 years of service life: save consumers time, money and aggravation
  • Longer cycle life: 70 percentage longer cycle life compared to conventional deep cycle batteries, up to 400 cycles at 80 percentage depth of discharge- high stable voltage for longer periods of time
  • Recharge: Highest recharge efficiency of any sealed lead battery on the market, capable of 100 percentage recharge in 4-6 hours; Mounting flexibility: Non-spillable design

The final battery on this list is a dual-purpose option. Although we highly recommend using only deep cycle batteries for your trolling motors in marine vehicles, dual purpose batteries will do the trick as well. And, if dual purpose is your preference, the Odyssey is consistently a top pick among users.

With a long service life and a three- to four-year replacement warranty, the Odyssey allows buyers who want a dual purpose battery access to a high-quality product. It offers high stable voltage for a more extended period of time than many other deep cycle units and operates well under any weather condition.


  • Three to 10 years of service use (dependant on the frequency of usage)
  • 70% life cycle compared to exclusively deep cycle counterparts
  • 100% recharge within four to six hours
  • Vibration resistant, meaning it can withstand massive shock and impact


  • Three- and four-year full replacement warranty options
  • High stable voltage for more extended periods
  • AGM technology; no leaks, no maintenance
  • Operates at optimal levels in all weather conditions


  • Dual purpose is not optimal for exclusive deep cycle performance

Types of Deep Cycle Marine Batteries

When looking for deep cycle marine batteries, you are going to come across three main types:

  1. Flooded batteries
  2. Absorbed glass matte batteries
  3. Gel batteries

Their different energy outputs can differentiate these types. Energy output measurement is in amperes, so you can easily distinguish type based on the numbers listed for each product. You will also see a variance in price between products—this is usually a reflection of combined output level and lifespan of the battery.

Finding the right marine life battery for you is going to depend on how you are using it. Things to consider are the size of your boat, how frequently you use it, and what your budget is.

In order to determine which deep cycle marine battery is right for you, here is a quick breakdown of each of the types listed above:

Flooded Batteries

Also known as “wet cell” batteries, these are the most common type of batteries available on the market. Flooded batteries come in a variety of shapes and sizes and have several different uses.

Despite the use of lead plates and plate separators, flooded batteries are not sealed. Their gases are not recombined internally. Instead, they are vented externally. Any internal gases that are produced inside of flooded batteries are released into the environment around them.

Flooded batteries require maintenance with water to regularly replenish electrolytes that get out through the vents. They have high charge rates but do require more work to maintain.

Absorbed Glass Matte

Absorbed glass matte batteries are the newest in battery technology. They are lead-acid batteries that use fiberglass as separators between plates and wrappers to hold electrolytes in place. This allows all internal components of the battery to remain in place, making it impact resistant and the battery type that offers the least internal resistance. This lower internal resistance allows the battery to maintain internal heat during use; it also decreases charge time and increases voltage power compared to other battery types.

The elements inside AGM batteries form a “physical bond” vis a vis capillary action, which acts as a barrier to hold liquid inside of the glass matting. This makes the design spill-proof should the internal elements ever be exposed. AGM batteries boast a maintenance-free design that keeps you from worrying about potential acid leaks, messes while charging, or possible corrosion. They have all the power to do what flooded batteries and gel batteries can, but better.

Gel Batteries

Like AGM batteries, gel batteries are sealed. That’s pretty much all they have in common, though. A gel battery uses silica to transform sulfuric acid into a jelly-like consistency. This jelly is used as an electrolyte to power the battery. These batteries need to be stored upright to prevent leakage.

You also need to take care not to expose gel batteries to high amperage conditions. When this happens, the gel inside of the battery can scar, creating pockets that ultimately lead to the corrosion of the battery unit. Gel batteries boast a more reliable internal construction compared to flooded batteries but don’t even compare to the quality of structure found in an AGM unit.

Additional Tips And Tricks For Deep Cycle Marine Batteries

The deep cycle marine battery powers everything on your boat, so it is truly the heart of the vessel. As such, it’s essential to get the right one for the specific needs of your boat. So, consider what you will be powering; lights, GPS, the anchor, radio, and/or stereo systems; these will all be running on your battery, so get the one that makes sense for your boat.

In terms of maintenance, taking proper care of your battery will extend the life of it and ensure you get the most out of its performance.

Here are a few tips for maintaining your deep cycle marine battery:

  • Get the right one for your vessel. Figure out the power needs of your marine vessel before beginning your search. This information will give you an idea of the level of power required to operate it properly. To get optimal performance out of your vehicle, you need a battery designed to support its current power output.
  • Charge less frequently at the start. Charging 20% below the full capacity until the plate formation is complete is usually going to get a longer lifespan out of your battery. So, in the early days, make sure you’re not plugging it in on the regular.
  • Allow for cool off time. The operation of the battery, from discharge to recharge, requires a cycle that can heat the internal components of the unit. So, when not in operational use or hooked up to a changer, give the battery some downtime to cool off. This time is vital to extending the lifespan of the unit.
  • Use a voltmeter. Routinely checking the state of the battery will ensure you keep it in good health. A voltmeter will allow you to take volt readings to keep track of the battery’s performance.
  • Don’t charge when wet. Do not wet charge your battery with a sealed battery charger, or it will not fully charge. Ultimately, doing this will cause corrosion.

What Makes A Good Deep Cycle Marine Battery?

There are a lot of options out there for marine batteries—they come in a variety of sizes, types, and prices, and all possess very different features. Just keep in mind your needs. If you have a low-powered boat, then opting for one of the more lightweight deep cycle batteries is your best bet. Higher-powered, heavier vessels will require bigger, more robust options. Just ensure that you’re sticking with batteries that offer deep cycle power output. Otherwise, you won’t have your boat to reach its top performance potential in the long run.

How To Setup, Use, And Maintain Tour Deep Cycle Marine Battery


Similar to setting up a car battery, your deep cycle marine battery should fit into place with ease and a few connectors. The process is essentially the same as automotive battery installation, so you can install it and have your boat up and running in no time!

Safety is the first thing to keep in mind before beginning any battery installation. Every electrical system is going to require additional precautions to avoid any possible risks. With batteries, ensuring that the connections are correct is critical.

One of the other things that you need to consider with any electrical element installation on a marine device is ensuring it gets encased in a waterproof shell. A good one will protect the battery from the elements, keeping it operating at its intended capacity.


Compared to a car battery, which is designed to never fully discharge, a deep cycle unit requires regular discharge and recharge cycles. And, while deep cycle batteries can be discharged up to 80%, it is highly recommended that the user never allows them to go below 45%. This precaution will provide a much longer lifespan for the battery.

Generally, deep cycle batteries require little or no maintenance, but with any component of a vehicle, you should keep an eye out for certain things and do check-ins, wipe downs, and charges when needed.

Maintenance Tips

  • Recharge dead batteries as soon as possible. If they stay dead for too long, the ability to charge fully may start to deteriorate.
  • Check the electrolyte levels. If they are below the split ring’s splash barrel, you will need to refill with water (IMPORTANT: use deionized or distilled water ONLY). Refilling water is not applicable for AGM batteries, so you likely won’t encounter it if you opt for any of the ones on our list.
  • Clean all connectors regularly, including terminals and cable connectors.
  • Keep the top of the battery moisture-free.

Benefits Of Using A Deep Cycle Marine Battery

Deep cycle batteries are lighter and smaller than lead-acid batteries and offer a similar capacity. They often don’t require regular maintenance, such as top-ups on water and electrolyte measurements. The low internal resistance design offers users fast charging units with less energy loss.


Simply put, deep cycle batteries will last longer than regular or starter batteries. Their function is what sets them apart. They provide a stable energy source for motors that require a consistent flow of lower-power energy for longer periods. This is in contrast to their starter counterparts, which are designed to provide huge bursts of energy for the start-up and then charge in conjunction with the alternators while operating.


Deep cycle batteries require little to no maintenance. AGM technology keeps all internal components in check. Unlike gel batteries that have specific storage requirements or flooded batteries that need electrolyte monitoring and water top-ups, deep cycle batteries can be mounted whichever way necessary and do not require tracking of internal fluids.


Consistent energy is the name of the game with deep cycle batteries. Because of this, they are highly efficient and can last up to 10 years with proper care. Deep cycle batteries are seen as a great energy alternative as of late and are possibly a longer-term solution to our extensive reliance on fossil fuels.

When it comes to charging your battery, consider its design. You should choose a charger that makes sense for the construction of your existing unit. And, not all chargers are created equal. Just like different batteries are designed for different devices, different chargers are designed for different battery types.

There are three types of chargers available for a deep cycle unit. These are absorbed glass matte, valve regulated lead-acid wet cell, and gel cell. The wet cell is the most common kind used for this type of battery.

Why A Marine-Specific Battery Is Your Best Bet

When you go to your local automotive shop and ask for a battery for your boat, the associate is likely going to tell you that any battery will do—but they will be wrong. If you know nothing about boat-specific batteries and you’re only paying attention to cost (and possibly size), then you’ll likely listen to that sales associate and be very disappointed once you install your battery.

Here are some reasons to look for marine-specific batteries:

  • A marine battery has a specific design. It is uniquely created for use on a boat, offering users optimal performance for their motorized marine vehicles. These batteries can withstand a plethora of weather conditions and have internal components that will remain secure under pressure from waves and rough waters.
  • The discharge ability will enhance all devices on board. If you opt for a regular car battery, your start-up will be great! However, the consistent power needed to keep all of the devices on your boat operating smoothly, including your radio, GPS, lighting, pump, appliances, and motor, require a consistent energy source more akin to household batteries.
  • They are sturdy. Generally, cars don’t deal with immense upheavals of water, and when they do, it’s few and far between. Deep cycle marine batteries can handle these conditions regularly while protecting the internal components from getting destroyed.

How To Get The Most Out Of Your Marine Battery

A good marine battery isn’t cheap, so once you’ve got it installed, you’ll want to ensure that you get the most out of your battery by taking proper measures to extend its lifespan for as long as possible. It is common for marine batteries to fail early on, and this is almost always due to improper care.

So, here are some of the measures that you can take to make sure that you get the most out of that new battery:

Avoid Extreme Temperatures

Deep cycle marine batteries are known to be well-built. Theoretically, they can withstand almost anything the weather can throw at them. But, like anything, if you protect your battery from extremes, you will likely be rewarded a longer time with it. Extremely high temperatures will cause the battery to expand, pushing out power faster and forcing it beyond its normal limits.

Extremely cold temperatures will cause the battery to discharge at a lower rate, forcing it to exert more effort than it usually needs to.

Tip: Batteries do tend to last longer in warm environments than in cold ones. Keep this in mind when storing your boat over the winter. If you live in a climate where the temperatures drop significantly, you may want to consider removing the battery for the off-season and storing it in a warm indoor space.

Charge Properly

You’ll see a lot of customer reviews that note challenges with charging their deep cycle marine batteries. These reviews are usually due to incorrect charging methods. People get impatient and want to charge their batteries quickly, but this doesn’t work with marine batteries and will ultimately leave customers with a dead or unusable battery.

The issue with a fast charge lies in sulfation, which is a process that displaces internal components that give the battery its power. The high voltage charging causes these components to corrode, leaving the battery destroyed and useless.

Stick To Your Battery’s Intended Uses

Just like you shouldn’t use a car battery for a marine device, the opposite is also true. So, if you’re stuck with a dead car battery, pulling out your deep cycle marine battery to jumpstart it isn’t a great option for the lifespan of your boat battery.

Now, that’s not to say that you can’t use them for starting your car—a deep cycle unit can absolutely start a vehicle. So, in an emergency situation, if no other options are available, it’s a battery that you can definitely rely on for just about anything you need. However, keep in mind that you will likely be shaving time off of your battery’s overall lifespan when you do this.

Follow Installation Instructions

Just like a car battery, a marine battery needs to be installed correctly. Although it’s a simple process, double- and triple-checking that the connections are correct will ultimately save you from destroying your battery’s chances at a long life early on. If it does get installed incorrectly and is left that way, you run the risk of accidental fires, acid leaks, and possible explosions as well. Not just bad for your battery, but also the safety of you and your passengers.

Tip: Ensure you install inside of an appropriately sized battery box with cables and screws (as needed) to ensure the added protection of the battery.

Life Expectancy Of A Deep Cycle Marine Battery

The lifespan of your battery will depend on how much you use it. If you use your boat regularly all year, then you are probably looking at a lifespan of six to eight years. Boats used less frequently (seasonally, for example) can usually expect to have a battery that will last around ten years. These estimates are based on proper battery care and maintenance.

It’s also important to pay attention to the lifespan for different battery types. For instance, an AGM deep cycle unit can last up to eight years, whereas a flooded or cell battery will usually only last around five years.

Again, this is all about proper care and maintenance. If you follow manufacturer guidelines for your product, you should be able to make the most of its lifespan, which will get you many seasons of boating with a single battery.

Lifespan Versus Cycles

You may also want to note that lifespan and cycles are very different things when it comes to deep cycle marine batteries. Lifespan refers to the overall life of the battery, i.e., it is usable for x amount of years, whereas its cycle refers to how long it lasts between charges. This difference is a crucial detail to note when looking at specs for different products.

Additional Tips

Before we get to the final thoughts, here are some additional tips to make the most of your deep cycle marine battery:

  • Use the correct charger. You will find a manufacturer recommendation for a charger that best suits your battery when you purchase it. It cannot be stressed enough how important it is to utilize this recommendation and get the best charger for your specific unit.
  • Always recharge when your battery is dead. A marine battery is like a car battery: if it sits long enough, it will die permanently.
  • Remove corrosion. Although most deep cycle marine batteries require little to no maintenance, common sense comes into play here if you see corrosion forming on the terminals. A towel with a mixture of baking soda and water will remove this easily.


It’s necessary to mention again not to let the sales associate at your local auto store fool you; not all batteries are created equal. At first glance, car and marine batteries appear to be very similar, but this is not the case. The internal elements of a deep cycle marine battery are significantly different than their automotive counterparts. And, when it comes to marine vehicles, you want to ensure you buy the best fit for your own needs.

While all batteries store energy, you now know the differences between the three types that are out there. Also, you know that there are massive differences in how each battery type works. Understanding each type of battery is going to be very useful in knowing which ones are most effective for any kind of device or application.

So, if you are currently in the market for a deep cycle marine battery for your boat, we hope we have given you all the information that you need to get started along with a few great options to kick off your shopping shortlist. Good luck and happy boating!

Leave a Comment