Adding more electronic accessories like fish finders, GPS, and depth finders in your boat? You’ll need to have a deep cycle marine battery that can consistently provide a steady current. Here are our top choices for the best marine deep cycle batteries. One of which requires no maintenance, fast recharging, and a high amperage per hour.
What You Should Consider Before Buying a Deep Cycle Marine Battery
Aside from price, there are other deep cycle marine battery buying factors you should consider. These are the batter capacity, battery ratings, battery group, and battery technology.
Battery Capacity
A typical car battery is not meant to discharge most of its power and provides starting charge for your engine. On the other hand, a deep cycle marine battery should be able to provide most of its charging capacity over long periods. To calculate the battery capacity, you need to calculate:
- Estimated running time: This is a rough assumption of how much time your electrical appliances spend drawing power from the marine deep-cycle batteries. E.g., stereo (60 w) running time = 3 hours, electric fridge (60 w) running time = 10 hours, Cabin Light (15 w) running time = 4 hours, etc.
- Power consumption in watt-hours (Wh) for each appliance: This is done by multiplying your device’s watt-hour consumption rate by the duration of time. E.g., stereo (60 x 3) = 180 Wh, electric fridge (60 x 10) = 600 Wh, Cabin Light (15 x 4) = 60 Wh, etc.
- Total power consumed in Wh: Add the individual power consumption rates on all your electrical devices. E.g., 180 + 600 + 60 = 840 Wh.
- Convert the reading to ampere-hours (Ah): Battery capacity is usually measured in amp-hours (Ah). To know how much power will be consumed in Ah, take the rating in watt-hours (Wh) and divide it by the battery’s voltage and the depth of discharge, i.e., 840 Wh / 12 V/ 0.3 DOD = 2333.33 Ah. This value is an estimate of the amount of power that you need. However, we recommend sizing up for extra wiggle room.
Battery Ratings
The battery ratings on the marine deep cycle batteries describe the total amount of amps a new fully charged battery can deliver at 0 degrees Fahrenheit for 30 seconds. A good battery should have:
- Reserve Minutes: This is the amount of time in minutes that a fully charged battery can constantly sustain a load at 25 amperes and 77 degrees Fahrenheit before the voltage drops to 10.5 volts. The reserve minutes for a 12 V battery is 120/ 2 hrs. However, completely draining a battery is not a good idea hence the practical limit would be 60 minutes.
- Reserve Capacity: Reserved capacity is also called reserved minutes. It is used to determine how long a battery can last when connected to a specific load or electrical component.
- Amp-hours / Amperage Hour Rating: The amp-hour rating on a battery shows the amount of current it can continuously draw for 20 hours. A 12 V battery with a 100 Ah capacity will deliver about five amperes an hour for 20 hours.
Battery Group
A battery group is an industry standard used to record the dimensions of a battery in terms of height x width x length. You’ll find the battery group size info on the label of your battery or in the manufacturer’s manual. Before buying a new deep cycle marine battery for your boat, consult the old one for the specific dimensions that will actually fit.
The most commonly found battery groups are:
- Groups 24 and 24 F
- Group 25
- Group 34
- Group 35
- Groups 51 and 51 R
- Group 52
- Groups 58 and 58 R, etc.
Battery Technology
Batteries have improved in capacity and their ability to supply current over a long period of time. When shopping for a deep cycle battery, you’ll come across these three types:
Lead Acid Wet-Cell
A lead acid wet cell battery contains lead, lead oxide, plates, and an electrolyte solution. When all the parts are connected to make a complete closed circuit, a chemical reaction occurs between the plates, causing the charges in the electrolyte to move to the anode or cathode. This movement of charges brings about an electric current.
Lead-acid wet cells are mainly used in industries and other applications that thrive on large supplies of current. The lead-acid batteries are made to have an even number of plates, each supplying 2 volts. Some standard voltages include 2V, 6V, 12V, 24V, etc.
Pros
- Lead-acid wet cell batteries are almost four times cheaper than lithium-ion batteries
- They are more green. Since they are rechargeable, lead-acid wet cells contribute to less waste and intoxication to the environment.
- They are readily available and hence will continue to be a popular choice for deep cycle marine batteries.
Cons
- The contents in a lead-acid battery are easily spillable, which means the battery can only be operated in an upright position.
- It emits dangerously explosive gasses (hydrogen gas) during recharge and should be kept in the open areas during the process. It also emits corrosive gasses and should be kept away from sensitive equipment
- It requires constant maintenance practices.
AGM Batteries
Absorbed Glass Mat batteries have gained popularity because they require less maintenance and provide better vibration resistance unlike the lead-acid option. This makes them perfect for use as deep cycle marine batteries. The electrolyte solution in an AGM battery remains suspended in between the absorbent fiber mats made of glass instead of a freely flowing solution.
Pros
- No spills will occur even when the AGM battery is damaged or broken. This also makes the battery a non-hazardous material, especially for marine use.
- They are shock resistant. AGM batteries were initially made in the 1980s for military use. They were designed to withstand shock and vibrations from military planes, cars, etc.
- Unlike other wet cell batteries, AGMs are not damaged by extremely cold temperatures.
- Since they are spill-proof, they can be installed in any orientation.
- They require less maintenance, produce minimal gassing, and have a longer lifespan than most batteries.
Cons
- The high manufacturing cost makes AGM batteries more expensive to purchase.
- They have a lower energy output, making them best for moderate loads and short-distance uses.
- It offers half the life cycle during deep cycle applications.
- Its lifespan reduces every time you overcharge it, requiring supervision during recharging.
Lithium Batteries
Lithium-ion (Li-ion) batteries have grown in popularity over recent years because they have proven to overcome the problems brought about by other generations of batteries. A lithium battery consists of an anode, cathode, a separator between the two plates, and an electrolyte that fills the spaces. The movement of lithium ions within the battery brings about the flow of electrical current.
Pros
- Li-ion batteries have a high energy density when compared to AGMs, lead-acid, and other battery types. This means that they can provide more charge over a long period of time using a single cell.
- The rate of self-discharge in li-ion batteries is significantly lower than in other rechargeable batteries such as Nickel Cadmium and NiMH.
- Lithium batteries require no maintenance practices and have a longer lifespan than lead-acid batteries.
- Since they require less power for recharge and infrequent charging, they reduce the cost of energy consumption bills.
Cons
- Because of their high cost of manufacture, lithium batteries cost up to four times more than a lead-acid wet cell for the exact specifications.
- Most of the equipment available today are not designed for electrical connection to a lithium battery.
- They are fragile and require periodic inspection and a protection circuit to guarantee safe operations.
What Are the Best Deep Cycle Marine Batteries?
The best deep cycle marine batteries should be able to provide steady current to power up your boat’s electronic components and devices. After exhaustive research, test, and taking into account customer reviews, we’ve found the following deep cycle marine batteries to be the best in the market today.
1. Mighty Max Battery CB19-12 SLA AGM Deep Cycle Battery
The Mighty Max battery is one of the cheapest AGM batteries. Its low price doesn’t mean that Mighty Max Battery compromised on quality. It works just as well as any other AGM would.
The sealed lead-acid and absorbent glass mat technologies make the battery leak and spill-proof, protecting all your electrical components from corrosion. It also requires minimal to no maintenance and ventilation and can be installed at any angle.
However, the battery is sold without mounting accessories and can only be used for small boats. WE recommend buying two batteries and connecting them in series to get more amp-hours for a price less than a top brand battery.
3. Optima Batteries 8037-127 D27F YellowTop Deep Cycle Battery
Optima claimed that their batteries have the fastest starting time, are vibration resistant, and last twice as long as other wet cell or gelled batteries. The Optima YellowTop, in particular, is designed to supply large amounts of current, making it perfect when installing heavy loads.
It has enough power to work as a cranking battery and a deep cycle battery. This battery gives you peace of mind that your electrically demanding appliances will still run smoothly even when the engine is on.
4. Banshee LiFeP04 Deep Cycle Battery
Banshee’s Lithium-ion Deep Cycle battery model is lightweight, long-lasting, and has excellent money value. It weighs almost 60 percent less than other size 31 deep cycle marine batteries and has a lifespan of up to three times longer than any AGM or SLA model with the exact specifications.
Its state-of-the-art battery power management system protects the battery from overcharging, short circuits, and excessive discharge. Other impressive feature is its 70 percent more cold cranking power. But what made a long-lasting impression is its Emergency Start feature, which is pretty convenient to have when the battery fails to start your boat.
5. Ampere Time Lithium LiFePO4 Battery
The Ampere Time Lithium Battery is a great alternative to Banshee’s deep cycle battery. It uses the same lithium technology to provide you with a highly efficient battery for your fishing needs. So, what’s the difference?
Banshee can only provide 100Ah while Ampere Time offers twice more – 200Ah! And, unlike lead acid batteries, you will get over 4000 cycles and up to 10 years of service life. If you are worried about durability, don’t be. This Ampere Time deep cycle marine battery is IP65 waterproof and vibration resistant.
Odyssey 31M-PC2150ST-M Marine Dual Purpose Battery
If you want a versatile deep cycle marine battery, you should consider picking up this Odyssey battery. It’s a dual-purpose, meaning you can either use it as a starting battery or a deep cycle battery. Even as a trolling motor!
This versatility is due to the battery’s impressive 400 cycles at 80% discharge. It can efficiently power up your on-board electronics, use it for trolling, and provide you with 1000+ cold cranking amperes.
Recharge is impeccable too – you are looking at 100% recharge in just 6 hours. Since it has a non-spillable design, you can install this battery using any orientation that fits your needs. It is also tolerant to high vibrations and extreme temperatures (- 40 degrees F to 176 degrees F).
7. VMAX SLR125 AGM Sealed Deep Cycle Battery
Thanks to its 125Ah and a whopping 260 RC, the Vmax Sealed Deep Cycle Battery has no problem powering up your boat’s devices. It also has a lifespan of 10 years in float mode and a one-year warranty. It does not produce dangerous fumes or gases during use, making it safe for your family vacations.
But VMAX’s efficiency comes with a price – it’s heavy. Comparing to other deep cycle marine batteries, the size 31 VMAX SLR125 weighs 75 pounds. If you
Reviewer’s Note
And, there you have it – the best deep cycle marine motor batteries available right now. If you are still uncertain of what you should buy, start by computing the total power consumption of each electronic component, accounting the run time. From there, look for a battery that can sufficiently supply that power. Don’t forget to consider the recharging and discharging capacities and other features.
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