How to Choose a Deep Cycle Battery for Your PV System

Providing power on the go has been something that we’ve done for a long time now, and batteries are the one component that has allowed us to do so efficiently. For a device to be able to have access to electric power, it needs to either have a direct source of it or have it stored somewhere. Batteries are known for the latter and they have been implemented in all kinds of devices and systems. One of these systems is the household solar panel system. There are plenty of reasons to use solar power and once converted and collected it needs to be stored somewhere if you want to use it at a later time.

solar panels energy storage

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Well, this is where deep cycle batteries come into play. These batteries are the marathon runners of the battery world. If you want to have continuous power output available to all of your appliances and devices, then deep cycle batteries are the ones to go for as they provide just that. They discharge slowly at a constant voltage, meaning whatever you have hooked up to your PV system will work the way it’s intended to. But which type of deep cycle battery should you get?

What Is the Best Deep Cycle Battery?

AGM

The most popular solar deep cycle batteries are absorbed glass mat batteries. These are, in fact, lead batteries that contain a special type of fibreglass mat. An AGM 100ah deep cycle battery is a low maintenance option that can handle vibration and shocks quite well. Furthermore, a 100Ah AGM battery has a faster recharge rate than a typical lead-acid battery, as well as a longer lifespan. Also known as dry batteries, AGM batteries don’t have an electrolyte fluid in them to spill making it easy to install them virtually anywhere. You can even install one upside down if there’s not enough space for it to be installed how you normally would.

Agm flooded gel batteries compared in a table

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Flooded (Lead Acid)

The typical lead-acid batteries that I just mentioned are known as flooded batteries. This is the oldest type of 100ah deep cycle battery. Lead-acid batteries are inexpensive but also not that great at providing a constant charge for a long period of time. While they can do that, they are not as durable nor do they offer as high of a discharge rate. Flooded deep cycle batteries can withstand overcharging but they require more maintenance despite being a reliable option.

Lithium-ion

The newest advancements in battery technology are built on lithium cell technology. Lithium-ion deep cycle batteries feature a unique approach when it comes to their core technology. They have high discharge rates, but they also have a high charge rate with little to no maintenance required to keep them running smoothly. Lithium-ion deep cycle batteries are lightweight and compact whilst having a high number of cycles, usually around 2,000 and 5,000. This means you can charge and discharge a Lithium-ion battery at least 2,000 times with some allowing you to do so up to 5,000 times.

Gel

Back to lead-acid batteries, we have gel deep cycle batteries that are valve-regulated. Although these batteries are spill-proof, they require special regulators. Gel batteries have a long lifespan and they are also robust and versatile with no off-gassing. Unlike flooded batteries, gel deep cycle batteries do not require maintenance.

What Makes a Deep Cycle Battery Suitable

Voltage Rating

The voltage of the battery is determined by the amount of power it needs to provide and the number of devices or appliances it needs to be provided to. The higher the voltage rating of a deep cycle 100Ah solar battery the more appliances it can supply.

agm versus gel batteries

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Discharge

The DoD or what is also known as the depth of discharge is a fundamental property of every battery. The DoD represents the total amount of energy being discharged from the battery. It is determined by how often you charge and discharge the battery. The more you use it the more you’ll charge and discharge. In this case, you’ll need a deep cycle battery with a higher DoD.

Shelf Life

The lifespan of any deep cycle battery depends on the chemical composition in it, its idle time and the temperature of the room you’re storing it in. What you should be looking for here is a battery with a low self-discharge rate and one that has a high number of charging cycles. When it comes to its operating temperature, well, that’s on you to keep an eye on.

battery bank storage

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Amp Hours

A key parameter you need to consider is the hours of use your devices have during the day. This will determine the amp hours of the battery needed to provide the necessary power to all the appliances and devices during the day. This specification is calculated by multiplying the wattage of the device by the hours it needs to run and then divide that with the battery’s voltage. This number is expressed in Ah and 100Ah solar batteries are the most commonly used ones.