Deep cycle battery vs. AGM – which between the two similar options is better?

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The technology that is used to make batteries has definitely come a long way, and it is no longer what it used to be – especially when you see that the first ones heavily featured wooden encasements and glass cells. Today, there is plenty of specialized technology, as we will see in this deep cycle battery vs. AGM.

The rise of different technology in making batteries leads to the rise of different types, and this means that there is plenty of confusion among users as to what type is best for something.

Many users will also assume that the types are the same, yet further research into this misconception reveals that these types are very different from each other.

What are the differences between the deep cycle and AGM batteries?

 
Deep cycle
AGM batteries
Approx. battery weight range (lbs.)
27 to 40
30
Reserve capacity range (in minutes)
140
100

 

Deep cycle vs. AGM – how these two compare

People that own RVs or boats might be familiar with deep cycle batteries, as they require their use much more than another type of battery. These types are also common for golf carts, as well as solar systems.

Both are also lead-acid (except for some cases of deep cycle batteries), and they have a similar approach to their working mechanism. All batteries will have these two slopes, which will then determine the other battery specs:

  • CCA, or cold cranking amps – these are the number of amps the battery can produce at 0OC or 32OF at a voltage of 10.5V.
  • RC or Reserve Capacity – the number of minutes that the battery can give out 25A, at a voltage of 10.5V.

When examining these two battery types, you will notice that they do not have many differences, since AGM batteries can be considered a type of deep cycle battery in many cases. However, when looking at their differences, the following observations come through:

Capacity for discharge

AGM batteries are great at handling spillage issues, just like deep cycle discharge ones. However, the capacity of discharge is slightly different for each case, as not all AGM batteries can handle deep discharge in the same way.

Deep cycle batteries have thick plates, which will allow for deeper discharge without the risk of damage.

The usual case is that the CCAs of a deep cycle battery, especially the LiFePO4 options, will be higher than typical AGM batteries, though the difference is not as great.

In addition to this, a deep cycle battery can handle several total or nearly total discharges without suffering damage – but this is something you will need to see whether the AGM battery can handle before doing it.

Discharge rates

As a general rule, deep cycle batteries will have lower discharge rates (especially for the Lithium-ion and gel types), at least when compared to a typical AGM battery. To know the discharge rate, the manufacturer will indicate the cold cranking amps of the batteries on the sheets containing the battery specs.

The CCA rating gives you plenty of information to work with, as the higher ones will allow for powering high-energy motors when starting engines. However, having a battery for solar and UPS use will require those with a lower CCA and higher discharge rate, which is where AGM batteries may possibly fall in.

Note that surge loads are not necessarily as important when choosing the specific battery though, as the loads are very similar for both AGM and deep cycle types.

Operation

Both batteries will take on different ways of optimizing their working mechanism. For AGM batteries, the aim is to allow you to give a large current supply, but for a shorter period compared to the deep cycle battery that spreads out its current delivery over a long time.

Deep cycle vs. AGM – a comparison review

Deep cycle battery – Overview and key features

Deep cycle batteries are primarily meant for nearly complete or full discharge on a regular basis, without the extent of suffering damage, unlike the traditional batteries. They use the same form factor as an auto battery, but deliver greater current amounts over a longer period of time.

There are many types of GAM batteries, and what probably adds to the confusion is that AGM batteries are normally classified as deep cycle types, but not all deep cycle types are AGM batteries. The different types are:

Calcium

This type uses calcium in place of antimony for the battery plates. Because of this, it has a number of advantages, which include increased corrosion resistance, prevention of gassing problems, lower self-discharge rates, and less water usage in topping up the battery.

It works best for under-bonnet dual battery systems. Note that if you are using it for situations that require you to discharge it deeply, it is always best to have a charger that has a charging mode comprised of calcium, in order to make the most from the battery.

AGM

This is the most common when it comes to auxiliary battery systems. As we will explain in the section of AGM batteries, this uses a fiberglass mat that is sandwiched between the internal plates, and acts as a sponge to prevent acid spillage.

Lead crystal

These are probably the most recent form of the deep cycle battery, having come to the scene in 2009. They are very unique, as the technology they use is patented and advanced.

Instead of the traditional lead acid that a conventional battery uses, they use a composite electrolyte comprised of silica (SiO2).

Lithium-ion

This is probably the lightest battery solution in terms of its weight, and is the safest form of Lithium batteries as it uses LiFePO4 (lithium-iron-phosphate).

These battery types can have a greater useable power by up to 60% more than the conventional battery, and they also are 30% more compact and 50% lighter than other batteries, making it a great option if you want to save space and weight.

You can explore some great options for deep cycle batteries, and they include:

Lifeline marine battery

Lifeline Marine AGM Battery -...
  • Voltage: 6 Volts
  • Amp. Hrs. 20 Hr Rate: 220
  • Minutes of Discharge @ 25 Amps - 492

If you want a reliable option of deep cycle battery that supports your marine operations duringtimes of low amperage, this is the choice to go for. You can be assured of its quality, as it meets the strict specifications of the U.S. Coast Guard and Military.

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Battle Born LiFePO4 battery

Battle Born LiFePO4 Deep Cycle...
  • BUILT-IN BMS: BMS stands for "Battery Management System" -...
  • LITHIUM ION TECHNOLOGY: Unlike Lead Acid batteries, Battle...
  • GREEN ENERGY BATTERIES: Made from 100% safe, nontoxic,...

This is a great AGM choice to have around. Its cycle life is also impressive, having between 3000 and 5000 cycles, and a full replacement warranty of3 years.

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What we like

  • They have a high depth of discharge and a steady power supply
  • Recharge quite fast compared to the traditional battery
  • Durable and reliable build

What we do not like

  • More expensive than other battery options
  • Less output of specific energy

What can you see with deep cycle batteries?

  • You will not see many issues with electrolyte spills
  • Come in different types, and choice depends on various factors
  • Maintenance free, except in certain types
  • Deep discharge is not an issue for them

AGM battery – Overview and key features

AGM technology stands for the Absorbent Glass Mat, which might sound very strange when you first hear the term, but actually makes sense when you look into its structure.

Instead of taking the traditional battery approach that uses lead plates to react with the acid, this one will use a mat made of fiberglass plates that absorb the sulfuric acid instead of letting it spill out. This results in them becoming spill-proof.

These batteries are also referred to as SLA (Sealed Lead Acid) or VRLA (Valve Regulated Lead Acid) types. The technology used to make them is fairly recent, having first come up in the mid-1980s.

They quickly became popular because of their lighter weight compared to most battery types, as well as the less hazards involved when handling them, which proved to be very useful for both aircraft and cars alike.

They allowed more users to transport the batteries easily without the dangers of leaking, and the fiberglass mat also allowed for changes in the battery design to take on a cylindrical form instead of the rectangular design.

Another difference worth noting is the smaller acid amounts compared to traditional batteries, which the fiberglass mat will absorb even when the battery breaks.

Varieties of AGM brands

There are some varieties of AGM brands in the market, which include the following:

XS Series Power D3400 AGM battery

XS Power D3400 XS Series 12V...
  • 12 Volt battery with CA: 1000, Ah: 65
  • Absorbed Glass Mat (electrolyte is suspended in fiberglass)
  • Spill proof, sealed, valve regulated and vibration resistant

This will work for you if you happen to own a racing car, as the electrical resistance levels are quite low and it is easy to mount in a variety of positions as it is resistant to vibration and spillage.

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Optima RedTop 8020-164 35

Sale
Optima Batteries 8020-164 35...
  • 12-Volt, 720 Cold Cranking Amps, Size: 9.38 x 7.69 x...
  • Reserve capacity of 90 minutes for constant performance
  • Optimal starting power even in bad weather. Case material is...

If you want a tough riding battery, this is probably the first place you will turn to. Its structure allows for it to deliver serious power to the battery when you need to. The interesting thing is that it continues to grow more powerful as you use it, so it will perform well even after an intense task. This makes it a great option for heavier equipment, automobiles, stock cars, and diesel cars.

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ACDelco 94RAGM battery

Bosch Automotive 6031C 6031C...
  • High Efficiency Particulate Cabin Air Filters are designed...
  • Without adding formulated chemical odor neutralizer, Bosch...
  • Melt-blown electrostatic layer and very dense media provides...

This is highly appealing both in weight and design. The battery is made of a calcium-silver alloy, and the vent cap will repel any leaks and improve the long term performance.

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Universal deep cycle battery 

Bosch Automotive 6031C 6031C...
  • High Efficiency Particulate Cabin Air Filters are designed...
  • Without adding formulated chemical odor neutralizer, Bosch...
  • Melt-blown electrostatic layer and very dense media provides...

This is probably the best compromise for those that want AGM batteries but without forking out as much as you would when you are buying an Optima. The only problem that comes with it is the size – it is quite big, so you need to make sure it fits in your car.

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Odyssey LTV 65-PC1750T

Bosch Automotive 6031C 6031C...
  • High Efficiency Particulate Cabin Air Filters are designed...
  • Without adding formulated chemical odor neutralizer, Bosch...
  • Melt-blown electrostatic layer and very dense media provides...

Among the best AGM batteries for their battery performance, this ranks among them. The manufacturer behind the product even claims that the battery life supersedes other batteries by as much as 70%, with a relatively shorter charge time of 4 to 6 hours.

View Price on Amazon

What we like

  • These batteries are spill proof
  • Durable and high-quality build
  • Easy to mount
  • Have a high power output
  • Reliable use and safe
  • Longer lifespan

What we do not like

  • Can have issues with overcharging
  • High cost of manufacturing
  • Have issues with declining capacity as they age

What can you see with the AGM battery?

  • Lower internal resistance compared to other batteries
  • Fiberglass structure makes them spill proof
  • Easy to recharge and use
  • They perform very well in lower temperatures

Verdict: So which is the winner? The deep cycle or the AGM battery?

Since these two are very similar to each other, it can be difficult to say which one is better than the other. However, from a general use standpoint, it is a better option to go for the deep cycle battery, as it has many more applications for you and an ability to discharge deeply, which you might not always find with the AGM battery.

Keep in mind though, that your choice will depend on several factors, such as what you want to use the battery for, as well as the purpose you want to accomplish.

Frequently asked questions

What is the battery type I should use for an RV?

The answer to this, especially when comparing AGM and deep cycle ones, will lie in the power consumption you are using, the space in your engine, and the battery you can afford. The only thing to note is to avoid using regular batteries because of their short operation life and the safety concerns, since you will need to deep discharge the battery at times.

Can I use a deep cycle battery to start an engine?

In theoretical terms, it is possible to do so. The only exception to this is when you use a deep cycle marine battery, and in that case you are better off buying a dual purpose model.

When I buy a car, why can’t I have an AGM or deep cycle battery supplied with it?

The reason behind this is the high production cost that AGM and deep cycle batteries in general have, which results in their price being more expensive compared to a regular battery.

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