Cranking Marine Battery VS. Deep Cycle Marine Battery

As long as your boat's battery seems to be working, you might not give it much thought.

But boat owners who want to keep their vessels going as long as possible should consider buying high-quality batteries. It is helpful to make deep knowing how they work. In this blog, you will learn whether the marine starting battery can be used as a marine deep cycle battery.

When you are shopping or replacing batteries for a boat, it is important to know what kind of battery is right for your needs.

As technology advances, more and better battery options become available, like a 10-page menu, more options can make you more confusing. It can be harder to choose!

The marine battery has different chemistries, uses, and sizes. Before you make your pick, it is better to know what a deep cycle marine battery is, what a starting marine battery is, how does it work, and what type is the best?

Boat Battery Terms

Thinking of this basic terminology as an appetizer. Being familiar with boat battery vocab will help you understand the confusion on specs and jargon you might come across when it’s time to shop.

Amp Hour (AH)

This is referring to the amount of energy a marine battery can store. The higher the Ah numbers, the higher the capacity.

One cycle is the complete discharge and full recharge of a battery. A deep cycle battery typically has a cycle life, which is the number of cycles you can discharge and recharge a battery before its capacity reaches 80% -98% of what it once was. But, most batteries reached 80%-98%, and they need to be replaced. 

C rate (or Capacity Hour Rate)

This is a measurement of how quickly your battery charges and discharges. It's usually expressed as a ratio between current drawn, battery capacity, and time, with most deep cycle marine batteries having a standard 20-hour rate. The number twenty refers to a discharge over a twenty-hour period. For example,  a battery has a 100AH capacity with a C20 rating which has an output of five amps for twenty hours until it is discharged.

Depth of Discharge (DOD)

The DoD of your battery is the percentage of total capacity that you drain before recharging. For instance, if the battery has reached 60% DOD, it means that the battery has 40% capacity left. A battery with a 100 amp-hour capacity would have 60% DOD if you drained it to 40Ah.

Internal resistance

Internal resistance describes how much a battery resists energy while it is being charged. The lower the internal resistance, the more efficiently the battery will charge. If internal resistance is too high, the battery may get hot while charging because it converts some of this lost energy into heat. 

State of charge

This is how much charge the battery has. For example, a fully charged battery has a 100% state of charge.

The difference between starting marine battery and a deep cycle marine battery

First, I will discuss deep-cycle marine batteries.

With a deep-cycle marine battery, you can expect it to provide consistent power for a prolonged period. These batteries can also give out surges of power. However, this is not their main purpose. If you use them as starting batteries, they will probably give out lower cranking power than what you would get from using regular starting batteries. One thing to note when it comes to deep cycle batteries is that when they are discharged, the best thing to do is charge them at a lower amp rating but for a longer period. Don't expect them to be fully recharged quickly; if you charge them for a short amount of time only, it will shorten their lifespan.

Cranking batteries are designed to rapidly start your trolling motor. These batteries have thinner plates than other batteries, which means they can provide large amounts of energy, it is perfect for getting your motor going.

If you try using a cranking battery for a tortoise job, like your trolling motor and other electrical accessories, you will soon realize that you must get back to the battery store again. Because your battery is unable to withstand the rigorous, constant discharging, it is going to overheat and probably quit for good.

What is a Cranking Battery

A cranking battery allows a marine vessel to start, providing power to the engine when the ignition is activated. The cranking battery is also known as starting battery for that reason. To start a trolling motor, short and strong bursts of energy must be provided from the cranking battery. The more plate surface area exists in the battery, the easier it is for the battery to provide the necessary power. That is exactly why the cranking battery has many thin plates, to increase surface area and makes starting a marine vessel as smooth and reliable as possible. Of course, those elements make a starting battery ideal for cranking an engine but make them less than ideal for continuous use, which is why a deep cycle marine battery is another boating necessity.

Starter batteries are designed to provide a high current flow, which allows them to quickly start a vessel engine. Most starter batteries are rated in Cold Cranking Amps (CCA), which is defined as the number of amps a battery can deliver at 32 degrees F (0-degrees C) for 30 seconds and maintain at least 1.2-volts. It means that the higher the CCA rating, the higher its cracking ability (the opposite holds true). There is no direct correlation between a battery's CCA rating and amp-hour storage capacity. The starter battery is designed with thin plates to achieve low internal resistance and maximum surface area allowing for maximum current flow.

Starter batteries are designed to provide a large burst of current for a short period. This surge of current turns the engine over during the starting process and then the alternator takes over. The burst of energy only discharges the battery 1- 3% and then is topped off by the alternator. 

Cranking Battery Design Features

The more plate surface area inside of the battery, the easier it is for that battery to send the necessary power. Because a cranking battery has many thin plates, which is increased surface area and make starting a marine vessel as smooth and reliable as possible. That's why a deep-cycle marine battery is another necessity for boaters.

What is a Deep Cycle Marine Battery?

It is time for the main course: What is a deep cycle marine battery? This type of battery allows you to power multiple electronics including trolling motor, radio, GPS, fish finder, and other gadgets on your boat ( also RV stuff). It is different from a cranking or starting battery, which we’ll discuss more in depth below.

A deep cycle marine battery is designed for use in situations where the battery will be charged and discharged many times over a long period of time. This is why it has thick, heavy plates and can withstand rigorous charging and hundreds of cycles without losing its capacity.

Much like the tortoise in the fable The Tortoise and the Hare, the deep cycle battery is a slow-and-steady source of power. It has a limited amount of instant power. This is why you are unable to use them to start your motor. So you need a starting or cranking battery, which we will discuss below.

When the boat's engine has started, it no longer needs quick and powerful bursts of energy from a cranking battery. Instead, the boat's engine needs continuous and reliable power for trolling motors, which is where deep-cycle marine batteries come in. The deep-cycle marine battery consists of fewer internal plates, but those plates are thicker. So the deep cycle battery is able to provide continuous power output over long periods of time. It means that the deep cycle battery can be entirely drained and recharged many times over and over again. But the cranking battery can not, it only ensures a boat can easily start and get out on the water while a trolling battery lets it keep reliable power along in any conditions. Deep cycle marine batteries are also unable to overheat since their thicker plate construction can withstand high temperatures during heavy currents.

Deep Cycle Marine Battery Design Features

A deep cycle marine battery (trolling motor battery) is designed differently than a cranking battery. Deep cycle batteries have fewer and thicker plates that allow the battery to operate continuously with a power output over longer periods of time. The deep cycle battery is able to be entirely drained and recharged many times over. Cranking batteries are designed to provide power in short bursts, rather than continuously. A deep cycle marine battery is much less likely to overheat since its thicker plate construction can withstand high temperatures during heavy currents.

Is there has Dual Purpose battery?

Yes, there are. Dual-purpose batteries can serve as both starter and deep-cycle batteries.

While a dual-purpose battery has some characteristics of a cranking battery and deep cycle battery, they do not quite measure up to either one. Most batteries won’t have as much oomph for starting motors as a true cranking battery or withstand as many cycles as a deep cycle marine battery.

Dual Purpose Marine Batteries

Of course, every rule comes exceptions. There are dual-purpose batteries that can work for both cranking and trolling motors. However, the dual-purpose battery is not necessarily the right option for every boat. Although it means that one less battery to purchase and reduces the total weight on the boat, like many 2-in-1 options, it does not always allow a vessel to perform at the same level as two batteries would do. For example, a deep cycle battery is built to withstand many discharges and recharges while trolling motor battery is not. Therefore, a dual-purpose battery falls somewhere in between. Many batteries do not stand up well to total discharges. Dual-purpose batteries can more prone to overheating in harsh conditions, which is certainly not ideal while a boat is out to sea. Still, this type of battery might be working well for short trips if they are used and maintained properly.

Overall deep-cycle marine batteries and trolling motor batteries are both necessary components of a safe and reliable marine vessel, but knowing the differences between them is key.

Starting battery and deep-cycle battery primarily differ by the demands and discharge they can withstand.

A starter battery, also known as a cranking, lighting, and Ignition (SLI) battery is designed to send maximum power for a short duration of about 1-3 seconds. Despite, the starting battery having the ability to generate high current, it cannot handle deep discharges without permanent long-term effects. Conversely, a deep-cycle battery can provide continuous power instead of short surges of power. It is designed to handle the cyclic demands of deep discharge.

Why can you not use one battery for cranking & trolling the motor?

It can be tempting for any boater to prefer to minimize accessories and additions to their vessel, but the truth is that it is very difficult to combine the performance of a deep cycle battery and a cranking battery into one. The main reason is that a cranking battery is subjected to continuous use, such as during trolling, it is subject to overheating. By that same token, if a deep cycle battery is called upon to provide the bursts of energy necessary to start an engine, it won't be performed. To ensure the best performance, most marine vessels require two batteries.

Types of Deep Cycle Marine Batteries

Are you looking for a deep-cycle marine battery in the market? Which type should you choose? That depends on several key points:

How much are you willing to spend upfront?

How long do you want your battery to last before replacing

How much total weight you can allow on your boat?

Where/in what position you will install your battery

Whether you want to maintain your battery or spend less on maintenance-free.

Below, we’ll discuss the most popular deep cycle marine batteries on the market right now:

Lead Acid Deep Cycle Marine Batteries

The main components of lead-acid batteries are lead plates and acid. The kind you use in your boat is called flooded lead acid (FLA) batteries. This battery contains sulphuric acid and distilled water. You have to replenish the distilled water to maintain them from time to time.

Advantages: The Lead-acid battery is the cheapest upfront option. Since they are popular and easy to get. If you take care of them properly, they can last around 3-5 years (Keep in mind that the number of years varies based on how much use you give them.)

Disadvantages: a Lead acid deep cycle marine battery is very heavy– about 80 lbs of extra weight on your boat per 12v battery. Hauling them on and off can be quite a chore, not to mention the constant maintenance they require, and the increased cost of gas.

Gel Deep Cycle Marine Batteries

Like a lead-acid battery, a gel battery contains liquid electrolytes. However, this battery has silicates that gel these electrolytes together. The gel is able to eliminate the risk of damage from vibrations and rough seas. Gel battery is an improvement over FLA battery, but more advanced technology in marine batteries is available.

Advantages: The key advantage of gel batteries is that they can tolerate long periods without being charged. Also the gel battery has a self-discharge rate of 1% per month. You can install them in any position in your boat (except upside down).

Disadvantages: The gel batteries have twice as expensive as FLA batteries, and the gel battery has a lower capacity for the same amount of space. They also require a special type of charger and do not handle high discharge rates as well as other boat battery types.

AGM Deep Cycle Marine Batteries

AGM stands for Absorbed Glass Mat. This battery has thin fiberglass matting between its lead acid plates. These plates are saturated with acid. Because AGM batteries are so tightly packed, they are highly shock resistant.

Advantages: AGM battery is an improvement on the FLA battery. You do not need to be refilled with water and can recharge faster than traditional batteries. They self-discharge at a rate of about 3% per month, and they won’t spill acid. So you can install them sideways on your boat if need be.

Disadvantages: The AGM battery is susceptible to overcharging, which can ruin itself. They are more expensive than FLA batteries of similar capacity. Also, the AGM battery has a shorter lifetime for its cost among all boat battery types.

LiFePO4 Deep Cycle Marine Batteries

If you are looking for an all-around good investment in a deep-cycle marine battery, LifePO4 is the right battery for people. Instead of lead plates and acid, it is built from lithium iron phosphate.

The latest in boat battery tech, LiFePO4 offers a host of improvements in overall battery types.

Advantages: The LifePO4 battery is the lightest of all deep cycle marine battery types. You can reduce up to 70% of the weight in your boat by switching to a LifePO4 battery. They are recharging faster and are leak and maintenance-free. See more advantages of choosing a LifePO4 battery for your boat battery here.

Disadvantages: The lone disadvantage of a lithium iron phosphate (LiFePO4) boat battery is its higher upfront cost. But when you consider its lifespan (5-10x that of other batteries), you are saving money in the long run.

What Deep Cycle Marine Battery Should I Choose?

If you’re looking to buy a boat battery, lithium iron phosphate (LiFePO4) is the way to go. These batteries are already popular among fishing competition enthusiasts, and they have many advantages for avid boaters or even occasional fishermen. Their higher upfront cost levels out when you end up replacing your boat battery less often. So, if you have the dough to purchase the tastiest item on the menu, why wouldn’t you? Unless you find the price tag too steep, there is no reason not to choose a LifePO4 deep cycle marine battery over other types.

Can you run deep cycle batteries and start batteries in parallel?

I would not advise actually putting two battery banks in parallel over long distances. It's just not a good idea. If you try to make starting battery and deep cycle battery in parallel, you will get yourself in a dangerous position.

How long do marine cranking batteries last?

The common battery's life is around 3-5 years, although they can last up to 6 years in the right conditions. The LifePO4 battery's life is about 7-10 years.

What's the difference between marine batteries?

A marine battery is designed with sturdier and more elevated plates for electricity. The reasoning is that the battery doesn't short circuit while bouncing around with the boat during rough waters, which is, of course, much different from being in a car on the road. 

Should I wire boat batteries in series or parallels?

It depends on your needs. Running batteries in parallel provides common voltage, however, for large applications beyond 3000 watts of power, using higher voltage series connections might be best.

Do deep cycle batteries recharge themselves?

To keep your batteries in top condition and extend their life, you should use the battery charger to charge them.

What do marine cranking amps mean?

CCA is the cold cranking amps rating, which tells you how many amps will be sent to the engine in cold temperatures. MCA or marine cranking amps are conceptually the same ratings, however, the CCA rating is based on amps delivered at 0℉, and the MCA rating is done at 32℉.

Do marine batteries have cold cranking amps?

The important rating for choosing an engine starting battery is Cranking Amps (CA) and Cold Cranking Amps (CCA), most marine batteries are rated in cranking amps as cold weather starting is almost rarely a requirement in boat applications, and the higher the CA or CCA, the more available power the battery will have to start.

How many cranking amps do I need for my boat?

Usually, a boat needs to get a burst of power to start the engine, so a cranking battery needs to deliver a large current to the boat for a short amount of time--often 75-400 amps for anywhere between 5 and 20 seconds, depending on your boat's engine.

Is dual purpose the same as a deep cycle?

Bear in mind, however, that most dual-purpose batteries won't start an engine quite as well as a true cranking battery and won't endure as many deep discharge/recharge cycles as a dedicated deep-cycle model.

What does MCA mean on a marine battery?

Marine Cranking Amps (MCA)

The MCA rating method measures battery output at 32℉, not 0℉. A battery's MCA rating is one-third higher than its CCA rating would be. To compare two batteries when one has an MCA rating and the other has a CCA rating, you can multiply the CCA rating by 1.3 for the equivalent MCA rating when one has an MCA rating and the other has a CCA rating.

Do batteries last longer in series or parallel?

Batteries last longer in parallel because the voltage remains the same if it is in parallel, but the amps increase. If you connect two 12v 100Ah batteries in parallel, it will still be a 12-volt system, but the amps will double to 200Ah so that the batteries will last longer.

How many years can a deep cycle battery working?

The common battery's life is about 3 to 5 years, and the Enjoybot LiFePo4 battery's life is about 8 to 10 years. Most deep cycle batteries can be extended their life and last longer with proper care and charging (depending on the frequency of use). It depends on the level of care on them, and whether your battery is not being damaged by the charging routine.

How long will a deep cycle battery last if it is not used?

A deep cycle battery can last for a long time without charging when it is not in use. Also, it is possible to recharge a dead deep cycle battery fully. The experts claim that depending on the size, type, and usage of the battery, it can last up to 30 days without being charged.

How often should you replace the marine battery?

Most marine batteries last anywhere from 2-5 years depending on the level of care them. Most batteries come with a one-year warranty. However, the Enjoybot LiFePo4 battery has 10 years warranty.

Are LiFePo4 batteries better than deep-cycle batteries?

Discharge: a LiFePo4 battery reached almost 100% (80%-98%) charge and discharge, with even the worst, having 80% of efficiency. On the other hand, Deep-cycle lead acid batteries typically have less than 80% charge-discharge efficiency, and they range from about 50% to 80%.

Is LiFePo4 a deep-cycle?

Yes, it is. The LiFePo4 batteries are the battery of best choice for deep-cycle applications. Lithium-Iron Phosphate (LifePo4) batteries are less than half the weight of their lead acid competitors.

Can marine deep cycle batteries be used in a car?

No, the common batteries can not be used in a car.

Only LifePo4 batteries can be used in both marine and a car, even golf carts, motorized wheelchairs and etc.

Is LiFePO4 the same as lithium-ion?

Not at all! The LiFePo4 battery has a cycle life beyond 4x of lithium-ion polymer batteries.

How long do LiFePO4 batteries last?

Approximately 5-7 years, but Enjoybot LifePO4 battery is about 10 years lifespan.

Are LiFePo4 batteries safe on boats?

Yes, LiFePo4 batteries are safe for marine and boat applications. LiFePo4 batteries are sealed, which means that moisture and even a bit of water splashing on them will not cause harm. Additionally, Enjoybot LiFePo4 batteries have an internal battery management system (BMS), which the system is keeping the battery in a safe condition.

Are all LiFePo4 batteries the same?

Not all LiFePo4 batteries are the same.

They are different because they are built with different quality control checks.

 Do boats need deep cycle batteries?

Actually, boats need both of cranking battery and a deep cycle battery. Deep cycle boat batteries provide power continuously. The cranking battery provides the short, big surge of power required to start the boat.

Which is better LiFePO4 vs lithium-ion battery?

Of course, the LifePo4 is better than a lithium-ion battery. Because the LiFePO4 battery has the edge over the lithium battery, both in terms of cycle life (it lasts 4-5x longer), and safety. In addition, the key advantage is that lithium-ion batteries can overheat and even catch fire, while LiFePO4 does not.

Conclusion

Enjoybot LifePO4 battery specializes in creating high capacity deep cycle 12 Volt lithium batteries ranging 100 amperes hours for a variety of applications and devices that require a long steady charge. Enjoybot lithium iron phosphate (LiFePo4) battery is in the program, it will be launched out in a few months.

 

Enjoybot deep cycle batteries are built to withstand many discharges and recharge while cranking batteries are not. Dual purpose batteries, therefore, fall somewhere in between both cranking battery and deep cycle battery. Many do not stand up well to total discharges (discharge beyond 50% of usable capacity).

Dual-purpose batteries are also able to be more prone to overheating in harsh conditions, which is certainly not ideal while a boat is out to sea. Still, the dual-purpose batteries can work well for short trips if they are used and maintained properly.

 

Usually, people choose to buy the starter battery and the deep cycle battery separately. If you are planning to purchase deep cycle batteries for your boat, I highly recommended the Enjoybot LiFePo4 batteries. See more advantages of choosing an Enjoybot LiFePo4 battery for your boat battery here.