Deep Cycle Solar Batteries (The Best Option For Solar)

When it comes to solar, you’ll need solar batteries that can deliver consistent power in all sorts of circumstances. The batteries should have a large capacity, fast discharge rates, and excellent round-trip efficiency. They should also be able to be re-charged quickly.

All of these characteristics are especially significant for those who live off the grid or in RVs (RVs). Deep cycle batteries are the greatest choice for these living circumstances.

This article is your guide to learn the following regarding deep cycle solar batteries:

  • What a Deep Cycle Solar Battery is.
  • Types of Solar Batteries.
  • Its durability.
Battery showing internal materials

What Are Deep Cycle Batteries?

A solar battery is simply a deep cycle battery, which is designed to store and distribute energy supplied by intermittent renewable sources such as solar panels over lengthy, repetitive, and deep charging/discharging cycles.

Unless you wish to retain power during utility grid disruptions, On-Grid systems do not require batteries however, they are required for off-grid systems and will likely provide a hundred percent of your electricity.

Recreational vehicles (RVs), maritime applications, and golf carts are examples of their variety of uses.

Deep cycle batteries are ideal for power-hungry equipment in RVs, such as air conditioners, refrigerators, induction cooktops, and microwave ovens.

How is A Deep Cycle Battery Different from a Regular Battery?

A normal battery should not be confused with a deep cycle battery. The latter is designed to provide brief bursts of power to start engines, but not for long-term deep discharge and recharge.

A deep cycle battery contains larger plates and denser active material to survive multiple charges and discharge cycles and may be used as both a starter and a long-term power source.

As a result, it’s also known as a dual-purpose battery.

See also: How Does a Solar Battery Work? An Ultimate Guide to Understanding Solar Energy Storage

What Are The Different Types of Deep Cycle Solar Batteries?

There are two different capacity ranges: 6 volts and 12 volts. There are three primary types of deep cycle solar batteries that are used:

1. A lead-acid battery that has been flooded

It is made out of lead plates or grids in a container filled with a liquid electrolyte, generally concentrated sulfuric acid.

It is also known as lead-acid, FLA, or wet-cell.

When comparing the weight of the battery to the quantity of energy it supplies, the FLA is rather hefty. As a result, this sort of battery is becoming less common.

It has been popular among budget-conscious and off-grid lifestyle practitioners since it is the cheapest and oldest battery technology. The disadvantage is that they require routine care like watering, charging equalization, and keeping the terminals clean.

These cells are commonly referred to as “wet” cells, and they are available in two types: serviceable and maintenance-free (which means they are designed to die as soon as the warranty runs out).

The serviceable wet cells, which have detachable caps and allow you to monitor their state using a hydrometer, are the better option.

2. Gel and AGM batteries with valve-regulated lead-acid (VRLA)

This battery is the next generation following flooded lead-acid batteries, and it was developed to address FLA problems.

The VRLA uses a thicker electrolyte rather than a free-flowing liquid electrolyte. It’s also sealed, which is why it’s also known as a sealed lead-acid battery.

VRLA comes in two varieties: gel and absorbed glass matt (AGM). A gelled electrolyte is used in gel batteries.

An electrolyte in a glass mat is used in AGM deep cycle batteries. There’s no need to add water because these aren’t free-flowing liquids.

The increased lead purity utilized in AGM cells is another aspect that boosts their effectiveness. Each plate no longer has to sustain its own weight due to the sandwich structure.

They can be charged and discharged considerably faster than other varieties because of their low internal resistance.

AGM cells are resistant to vibration and work well in low temperatures.

Although there are several benefits to utilizing a deep cycle AGM battery, they are generally twice as expensive as their flooded-cell cousin.

Due to their greater power density, these cells can carry about 1.5 times the amp-hour capacity of a similar size flooded battery.

3. The lithium-ion battery

It is a type of rechargeable battery. It comprises cathode and anode plates or cylinders immersed in a solution of lithium salts and is sometimes referred to as a lithium battery. It comes in a variety of chemistries and is the safest to use in an RV.

Lithium batteries are the most costly of the deep cycle battery types, although they last far longer than lead-acid batteries.

For a given capacity, they are physically smaller and lighter. They have improved performance features, such as a deeper discharge depth and reduced self-discharge, and can endure longer charge cycles if properly scaled and maintained (i.e., can have a greater lifespan).

On top of all this, these batteries require minimal user upkeep/ maintenance.

The most important factor considered to be a disadvantage for these batteries is them not being economical.

Lead-acid batteries are widely used for backup power in homes and are produced by a variety of companies however, lithium-ion batteries don’t currently have the same market as lead-acid batteries and are therefore more costly.

What Type of Deep Cycle Solar Battery is Considered The Most Suitable?

Each type of deep cycle battery has advantages and disadvantages. Because lithium deep cycle batteries are the most powerful, lightest, and smallest, they are the best choice for solar systems in RVs.

However, for those on a tighter budget, their price tag may be a hindrance.

What is The Life of a Deep Cycle Solar Battery?

It is dependent on a few parameters, although they are less than in the case of a lead-acid battery. They are as follows:

  • Appropriate upkeep
  • Properly draining and charging
  • When it’s below freezing outside, be sure you’re using the right equipment.
  • Temperature in the storage room for batteries

The charging cycle is a more accurate means of determining how long it lasts.

Depending on the manufacturer, type, and other considerations, lithium deep cycle batteries can last anywhere from 3,000 to 5,000 charging cycles. It might last anything from 3 to 20 years in terms of years.

When properly maintained, flooded lead-acid batteries can last up to 6 years. AGM batteries are the same way. Gel batteries have a somewhat longer life span, ranging from 10 to 20 years.

Can Different Solar Batteries Be Connected Together?

No. Only batteries of the same kind, model, capacity, and age can be connected. The wiring used to link them must be the same size and length as well. They should be grouped together as well.

The battery bank can be connected to the RV engine starter battery, but the battery bank can be located elsewhere in the RV.

To charge the house bank through the alternator or the engine battery via solar, you’ll need a battery isolator, battery combiner, or charging relay.

Why Do You Connect Deep Cycle Batteries In Parallel?

Deep cycle batteries can be linked in parallel to improve a battery bank’s current capacity. The battery bank provides DC power to an inverter, which converts it to AC power for use in appliances.

The inverter’s input, the type of battery you choose, and the quantity of energy storage you want will all influence whether you choose a 12 volt, 24 volts, 36 volts, or 48-volt battery bank.

How Can A Deep Cycle Solar Battery Be Efficiently Maintained?

Internal resistance causes heat and damage while recharging deep cycle batteries, thus they should never be discharged to less than twenty percent of their full capacity.

To prevent the sort of damage that may decrease the battery’s life, renewable energy systems typically utilize a low-charge or low-voltage warning light or a low-voltage cut-off switch.

The shelf life of the batteries will be extended if sorted at lower temperatures because the chemical processes in the batteries are slower at lower temperatures.

While traditional deep cycle battery systems need a high level of supervision, the next generation of energy storage (lithium-ion) has highly automated management systems.

There is hardly little maintenance or monitoring required for these batteries.

How Can You Charge A Deep Cycle Battery?

Recharging deep cycle batteries can be done in a variety of ways. An external charging unit linked to a source of electrical power, such as a wall socket, is the most frequent way.

The batteries are charged by solar panels using a battery charge controller in an alternative energy system, which guarantees that the maximum output from the solar panels or array is directed to charge the batteries without overcharging them.

In general, a deep cycle lead-acid battery can be charged at any rate that does not result in excessive gassing, overcharging or high temperatures.

The battery takes a lot of current in the early stages of charging when its state of charge is the lowest, but the safe current reaches a limit when the battery is completely charged.


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Elliot has 20+ years of experience in renewable technology, from conservation to efficient living. His passion is to help others achieve independent off-grid living.

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