5/51 rating

A standalone source of electricity onboard a boat or car is always a great idea. If you are looking for the best deep cycle marine battery, I hope this review will help you with your choice.

Our pick
Best Deep Cycle Marine Battery
Universal Power Group UB 121000
The Best Deep Cycle Marine Battery
You’ll be amazed at the wide range of products and appliances that you can power with this battery.

It is important to understand that deep cycle marine batteries are deep-discharge batteries ideal for supplying power to electronics and devices. Plus, by using them, you avoid the risk of overheating your electronics. This kind of problem has often been encountered when using a marine starting battery that will not provide a stable, constant flow of energy, but rather for a short period, these devices give you a large discharge of power to start your engine.

You should also know that all batteries that are described in this review are divided into 2 types: SLA and AGM. SLM means Sealed Lead Acid and, accordingly, AGM stands for Absorbent Glass Mat. The main difference between a deep cycle marine battery and other similar products is that the “components” of the battery are solid lead plates, not a sponge, with “absorbed glass mats” in between.

Battery Type Voltage Capacity, Ah Group size
Universal Power Group UB 121000 best overall SLA/AGM 12 100 27
VMAX V35-857 best for trolling motor SLA/AGM 12 35 U1
Interstate Batteries DCM0035 best small SLA/AGM 12 35 U1

Best deep cycle marine battery reviews

Universal Power Group UB 121000 – best overall

Universal Power Group UB 121000

If you have already been confronted with the choice of batteries, you probably know that Universal is very responsible for creating their batteries. Buying the best deep cycle marine battery is a very smart move because it is more versatile and practical than the same conventional AGM battery. This 100Ah capacity and 12-volt battery is equipped with an individual stainless steel cell that can be installed as well as reinforced. That is why, the flexibility of use is a big advantage.

By the way, just like other AGM batteries, Universal Power Group UB 121000 uses a very small amount of sulfuric acid as compared with flooded batteries. What’s more, this battery is absorbed by a fine fiberglass mat.

Another undoubted advantage is that this battery is absolutely spill-proof, so you can move it as you like without fear of harm or damage to the battery case. If we are talking about nice features, it is also worth mentioning that the Universal Power Group UB 121000 is designed in such a way that it prevents all mechanical vibrations. I think so many pleasant factors make this product irreplaceable as the best AGM marine battery on the market.

Key specs

  • Type: SLA/AGM (Sealed Lead Acid, Absorbent Glass Mat)
  • Nominal voltage : 12
  • Capacity, Ah: 100
  • BCI group size: 27
  • Float use charge voltage, V: 13.6-13.8
  • Cycle use charge voltage, V: 14.5-14.9
  • Self discharge, % : 3
  • Dimensions (L x W x H), cm/inch: 30.4 x 15.2 x 20.3/12.2 x 6.6 x 8.3
  • Weight, kg/lbs: 28.5/63.9

Pros

  • The battery comes with a totally spill and acid-proof body
  • Very solid and durable but still portable enough

Cons

  • Pretty heavy for transportation

Renogy RNG-BATT-AGM12-100

Renogy RNG-BATT-AGM12-100

Renogy RNG-BATT-AGM12-100 is a very reliable choice among all known products on the market. As the manufacturer himself means, the battery is specially designed for storing solar energy. In addition, I believe it is the greatest choice for both daily use and backup power.

Renogy Deep Cycle AGM batteries protect you from acid leakage and are maintenance-free. Patented five-piece alloy plates and specially treated plate grids provide low internal resistance and high discharge currents, up to 10 times the rated battery capacity. In combination with the 12 volt AGM12-100 system, it becomes, if not the most, then definitely one of the most reliable batteries on the market.

On account of the battery, the improved electrolyte formula ensures a stable 100Ah battery capacity and excellent discharge characteristics at low temperatures below 32 ℉ (0 ℃). Thus, the developers tried to minimize the deterioration in quality due to weather conditions.

Key specs

  • Type: SLA/AGM (Sealed Lead Acid, Absorbent Glass Mat)
  • Nominal voltage : 12
  • Capacity, Ah: 100
  • BCI group size: 31
  • Float use charge voltage, V: 13.5-13.8
  • Cycle use charge voltage, V: 14.4-14.5
  • Self discharge, % : 3
  • Dimensions (L x W x H), cm/inch: 33 x 17.2 x 22.8/13 x 6.8 x 9
  • Weight, kg/lbs: 30/66

Pros

  • Extremely versatile due to the fact that it can be used for different purposes
  • The greatest combination of quite a nice price and excellent quality

Cons

  • No actual cons found

VMAX V35-857 – best for trolling motor

VMAX V35-857

VMAX V35-857 is another good solution for those who are looking for sufficiently high quality and at the same time powerful battery. The design is beautifully done, although it needs some improvements. The battery has absorbed glass matt, which absorbs shock and prevents spillage. Thus, the V35-857 features good protection for your trolling motor and battery.

The best deep cycle marine battery for trolling a motor must include not only good protection but also power. To me, the V35-857 with a nominal voltage of 12 does its job perfectly. The maintenance-free operation of this battery is the most convenient feature as one does not need to check the gravity of the electrolytes and thus save a sufficient amount of time and effort doing that.

This battery boasts a 35 Ah battery capacity. Moreover, this device has a reserve capacity of 75 minutes with a discharge capacity of 25AH.

Key specs

  • Type: SLA/AGM (Sealed Lead Acid, Absorbent Glass Mat)
  • Nominal voltage : 12
  • Capacity, Ah: 35
  • BCI group size: U1
  • Float use charge voltage, V: 13.5-13.8
  • Cycle use charge voltage, V: 14.4-14.9
  • Self discharge, % : 1-2
  • Dimensions (L x W x H), cm/inch: 17.7 x 15.2 x 12.7/7.7 x 5 x 6.1
  • Weight, kg/lbs: 11.3/25

Pros

  • The battery is very convenient and fully maintenance-free
  • The battery comes with a special carrier that makes this product very portable

Cons

  • This device is absolutely non-waterproof and doesn’t have any vibration prevention
  • Screws and bolts are not very durable and not qualitative enough

Interstate Batteries DCM0035 – best small

Interstate Batteries DCM0035

The article describes several batteries, but they have one thing in common – they are approximately the same size. Therefore, if you are looking for a decent battery but smaller, I advise you to pay attention to this small deep cycle marine battery. This AGM battery Made up of a very strong exterior of tough plastic guarantees you decent power and at the same time good portability and versatility.

This small battery supplies 12 volts of current, power of 35AH, making it an excellent purchase for small needs. Absorbent Glass Material technology allows absolutely no worries about maintenance. This means the battery is also waterproof, which expands its range of applications. I use it for the needs of an undemanding boat, you can not be afraid of either water or overheating of the battery in the sun, and 35 Ah the battery volume will allow you to use it for a long time without additional recharging.

Key specs

  • Type: SLA/AGM (Sealed Lead Acid, Absorbent Glass Mat)
  • Nominal voltage : 12
  • Capacity, Ah: 35
  • BCI group size: U1
  • Float use charge voltage, V: 13.6-13.8
  • Cycle use charge voltage, V: 14.5-14.9
  • Self discharge, % : 3
  • Dimensions (L x W x H), cm/inch: 17.7 x 12.7 x 15.2/7.6 x 5.1 x 6.4
  • Weight, kg/lbs: 10/22.9

Pros

  • Very comfortable to move around and easy to set up and use
  • Due to the small size, charge takes much less time and works longer as well

Cons

  • Suitable only for limited goals and doesn’t suite for golf cars and small boats

Mighty Max ML55-12

Mighty Max ML55-12

Mighty Max ML55-12 is an excellent AGM and SLA battery for those who need a powerful battery for a golf car, electric vehicle or even a car. For these purposes, this product is the best marine deep cycle battery.

Mighty Max ML55-12 features 100% vibration resistance and fully waterproof housing. The last feature, by the way, allows you to use the battery in any position, due to the fact that the insides will not spill. Mighty Max ML55-12 is made out of tough ABS plastic, using calcium-tin alloy plates, with fiberglass mat separator and sulfuric acid as electrolyte.

Also, this 12V deep cycle marine battery boast a good battery capacity of 55 Ah and a comparatively low weight of 17 kg. The design of the Mighty Max ML55-12 adds portability with integrated handles on the body.

Key specs

  • Type: SLA/AGM (Sealed Lead Acid, Absorbent Glass Mat)
  • Nominal voltage : 12
  • Capacity, Ah: 55
  • BCI group size: 22NF
  • Float use charge voltage, V: 13.6-13.8
  • Cycle use charge voltage, V: 14.4-14.7
  • Self discharge, % : 3
  • Dimensions (L x W x H), cm/inch: 22.8 x 12.7 x 22.8/9 x 5.4 x 9.1
  • Weight, kg/lbs: 16.7/36.9

Pros

  • Very portable due to the relatively small weight and in-built handles
  • Safe and very secure build quality made of tough ABS plastic

Cons

  • No cons found except for relatively high price in comparison with similar batteries

Best deep cycle battery charger reviews

As you already know, when using a deep cycle marine battery, which, as we said earlier, have hard and thick plates, you will not get by with regular charges. For this purpose, you will need special chargers.
It is incredibly important not to neglect this, as quality chargers will increase battery life and provide mobility for your travels. It is on this basis that this article has selected several good options for these purposes.

NOCO GENIUS10 – best deep cycle battery charger

NOCO GENIUS10

If you are looking for a good and reliable charger for your battery, HOCO is worth checking out. These guys supply the best deep cycle marine battery charger to the market.

First of all, it is worth noting the coolest design and cool eco-friendly packaging of this charger. It is made in black and red colors and therefore looks very beautiful. The plug and socket have a rubber port cover to protect the contacts from dust and water, which is also an undoubted advantage. This charger supports 6 or 12 volts at 10 amps.

The battery clamps are very, very well built and have sturdy, massive metal clamps with a plastic cover around them. The cables are attached to the clamps with a screw. If you don’t need to use the battery clips, you can detach the cable and screw it directly onto the battery like a normal eyelet cable. There is a fuse on the positive cable.

Key specs

  • Voltage: 6/12
  • Amperage: 10

Pros

  • Built-in thermal sensor ensures trouble-free charging and prevents your battery from overheating or overcharging
  • Features both 6 and 12 voltage
  • Extremely well built with waterproof technology

Cons

  • Requires constant supervision while charging because it can overheat easily

Battery Tender Plus

Battery Tender Plus

When buying, many users expect to receive simple yet multifunctional chargers for their AGM marine deep cycle battery. This is exactly what Battery Tender Plus is. Due to its compactness and versatility, this charger has become a very desirable acquisition for charging a deep cycle battery for a boat or for a car.

Battery Tender Plus is a device with 1.2 A and a voltage of 12. Speaking of pleasant features, I would like to mention that this device automatically switches between charging modes and selects the one that is more suitable for your battery. Moreover, it is quite easy to use.

Key specs

  • Voltage: 12
  • Amperage: 1.2

Pros

  • Extremely easy to use and doesn’t require any additional maintenance
  • Нas a special indicator that after charging the battery will glow green and keep it in a fully charged state without overloading

Cons

  • Alligator clips are on the small side, making it difficult to clamp them onto larger posts

Buyers Guide

Benefits and drawbacks of using a deep cycle marine battery

Each product has both undoubted advantages and some disadvantages. Even 12V deep cycle marine batteries, no matter how cool they are, have some disadvantages. Let’s focus on the pros.
Firstly, you can not be afraid of discharge, because even if 10-20% of the charge remains, the battery itself will not suffer in any way. In addition to this, all such batteries are protected from overheating and have solid lead plates inside which only help in this matter. In addition, they have a wide range of applications for cars, golf carts and boats, etc.

Speaking of the obvious disadvantages, it is worth mentioning their significant weight, which makes transportation much more difficult. In addition, these batteries require careful maintenance. This is a very important point, because improper care can ruin your expensive battery very quickly.

Battery composition types

Deep Cycle Marine Batteries fall into two main categories: FLA (Flooded) and VRLA (Valve Regulated Lead Acid). This difference is very important to understand if you want to choose a really worthwhile product.

Flooded Batteries are electrolytic liquid inside. It is needed to completely immerse the internal lead plates. Thanks to this technology, although batteries require regular maintenance and water replenishment, they cost an order of magnitude less and are therefore a very popular solution on the market. In addition, they do not tolerate vibrations well, so they cannot be installed everywhere.

Gel batteries are also very popular. They do not have internal electrolytes, therefore they are much more resistant to vibration and not demanding on the location. Moreover, they are very durable and practically do not discharge themselves offline. Besides the pros, there are also downsides. For example, a gel battery requires a special charger that will charge it at a lower voltage.

In turn, the Absorbed Glass Mat (AGM) is the most popular battery on the market. Thanks to a special technology, they use electrolyte-absorbing mats that allow hydrogen and oxygen to combine in such a way that their own water is formed. Based on this, it is logical that they can be placed anywhere and in any way without problems. Most of all, AGM batteries are afraid of overcharging. It is due to improper maintenance that the battery can fail very quickly.

Marine battery capacity explained

As you already know, battery capacity is measured in ampere hours or Ah. The higher the capacity of the battery, the longer you can work with your devices, which is important for deep discharge batteries. It is also important to understand that you usually do not completely discharge the battery in order to extend its life, but only go to a value called the depth of discharge. The typical DOD is around 60%.

Even if you imagine a situation with regular use you will only waste 40-50% of the capacity of a deep cycle battery, you should think carefully and design a multi-battery power supply if you have high energy requirements.

What is the difference between cycle use and standby use?

In fact, it is important to know that there are 2 options for using batteries – float use and cyclic use. If you plan to use the battery in “float” mode, it will serve as an alternative power source. This is most needed during emergencies when the main power source is out of order. Many experts recommend charging it fully so that it is always ready for use at any time. Moreover, the charge voltage for this battery is much lower.

Unlike float use, cyclic usage type means that the battery can be repeatedly discharged and recharged . However, overcharging should not be allowed, otherwise 90% damage may occur and the battery will deteriorate.

BCI battery group size

Understanding the BSI group size battery is also very important for several reasons. Knowing the exact size of a BCI battery string helps you find a new replacement battery. Moreover, when replacing an old battery, you should make sure that the new battery suits your purpose, it has the same chemical composition, has the same components and specifications.

Many BCI battery groups differ by only a fraction of an inch and can be used interchangeably. Personally, I advise you to be sure to consult with a professional. You need to know for sure if replacing the battery with another group is a safe option. Otherwise, using a new battery may cause damage.

Can you use deep cycle battery as a starting battery

You can definitely use a deep cycle battery as a starting battery, but it’s about power. The point is, it should be oversized about 20% compared to the existing or recommended starting battery group size to get the same cranking amps. But be that as it may, deep cycle batteries are better suited for other purposes. Surely on board there is a bunch of electronics, kitchen or, for example, sounding stereos. For these purposes, the deep cycle battery is best suited.
You can use this battery as a starting battery. The battery will not be affected in any way. However, mostly the power will not be enough.

How to take care of your marine deep cycle batteries

You don’t need to be a professor to understand this. It’s easy enough: don’t neglect the elementary rules and everything will be cool. First of all, use a quality charger. Choose it wisely to make it the perfect match for your battery type. You should not arrange a derby for your battery in the form of a voltage drop, it will only spoil it.

Also keep in mind that there is a sulfation process. It occurs when the sulfuric acid in lead acid batteries reacts to form lead sulfate on the negative plates of the battery. The surface area of ​​the acid on the plates is reduced, making it difficult for the battery to hold charge. The best way to prevent sulfation is to charge the battery before storing.

Well, by the way, at the expense of storage. Always, I repeat, always, as far as possible, store the battery in a cool place that has ventilation. This is a must, because if you neglect this, the process of sulfation described above takes place.

How to сharge a deep cycle battery properly

First of all, it is no secret that you need to use the correct charger. You should determine between 5, 10 and 15 amps of charging. Remember that this is very important and you need to use quality products that are not worn out so that everything works without interruption.

For a good charging process, start charging the deep cycle battery components at 50% or higher capacity. Based on this, remember that you can never lower the charge level to a critically low level, because this way you put a very heavy load on the device.

Using a voltmeter or smart charger, you need to calculate in advance how much your battery should be charged. Next, it’s best to set a timer. This way you can avoid the silly mistake of overcharging your battery. It is also important to understand that temperatures and weather conditions also have an impact. Do not charge your device under the scorching sun, this will wear out the battery. Based on this, room temperature is ideal.

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