What is the difference between a solar battery and a deep cycle battery

What is the difference between a solar battery and a deep cycle battery

So you're a solar enthusiast and you've finally decided to buy a solar panel kit. What you may not have considered is what deep cycle batteries you need for your installation.

If you travel by van or truck, you'll need a way to store the power generated by the panels. If you use solar power at home, you may want to go off-grid or use a hybrid system with battery storage. There are many things to consider when deciding on a solar storage solution. Let's take a look at everything you need to know about solar energy storage with deep-cycle batteries.

What is a deep-cycle battery?

Deep-cycle batteries look like car batteries, but they are very different from them. Unlike car batteries, which only provide power for a short period of time, deep-cycle batteries are designed to provide power for a longer period of time. Deep-cycle batteries can be discharged to 80%, but most manufacturers recommend not discharging them below 45%. If this level is regularly exceeded, the life of the battery will be shortened.

What is the difference between a deep cycle battery and a normal battery?

We are often asked if deep-cycle solar cells are different from normal batteries. Ordinary batteries, such as those used in cars, produce shorter current pulses. On the other hand, deep-cycle batteries can provide a smaller but continuous amount of energy.

Deep-cycle batteries are popular in hybrid or off-grid solar systems because they can be fully discharged and do not fail as quickly as ordinary batteries. For example, a lead-acid battery can be discharged to a maximum of 50% to extend its life.

If you use solar panel batteries as part of a solar home system, you can store excess electricity generated by the panels instead of feeding it into the grid. When the batteries are fully charged and the panels are still generating electricity, the energy is fed into the grid.

Do I have to store my batteries?

Not all solar power configurations require battery storage. If you are grid-tied, you do not need to add batteries; however, hybrid solar solutions are becoming increasingly popular. However, if you have an off-grid lifestyle, or want to live and travel in off-grid areas, you will need a solar battery. Here are some situations in which you may need a deep-cycle battery

If you live in a caravan, van or motorhome.

Yes, if you live in a caravan, van or motorhome you will need a solar cell.

We strongly recommend the use of a battery such as the Renogy deep cycle battery in your caravan. If you add solar storage to your caravan's solar system, the solar panels and batteries can replace a gas generator. This allows you to run even when your panels are not producing electricity.

If you need solar power for your boat.

Yes, if you intend to power your boat with solar energy, you must purchase the right solar cells for your system.

While it is often tempting to buy just any marine battery, you should not assume it is safe. In fact, many marine batteries are not suitable for use in solar systems. Deep-cycle solar cells, on the other hand, are more reliable, so you'll have power even if you're in the water.

If you live in a house with grid access.

If you have access to the grid, solar storage is not essential, but it is useful in the event of a power outage.

Battery storage is very beneficial for homeowners, but it is not mandatory. However, hybrid solar systems, which can connect to both the grid and solar cells, are becoming increasingly popular. If you want to be off-grid or run your solar panels even during a power outage, battery storage is a good way to ensure a continuous supply of power.

What are the different types of batteries?

There are many options for deep-cycle batteries. The most common types used in solar installations are flooded lead-acid batteries, sealed lead-acid batteries, and lithium-iron batteries. Flooded lead-acid batteries are the cheapest option and can be purchased in most stores and workshops. Sealed lead-acid batteries store 10-15% more energy than lead-acid batteries and charge up to four times faster. Lithium-iron batteries are the most popular choice.Up to four times faster. Lithium-iron batteries are the most expensive option, but they also last up to four times longer than lead-acid batteries and weigh considerably less.

Flooded lead-acid batteries

Flooded lead-acid batteries are widely used and are the cheapest option. These batteries can be obtained from most major car dealers and distributors.

In a flooded lead-acid battery, the lead plates are immersed in an electrolytic mixture of water and sulfuric acid. During the charging and discharging process, a chemical reaction takes place that results in the formation of gases that are released from the battery. This outgassing process causes the electrolyte content to decrease and must be replenished regularly. This means that the useful capacity of a lead-acid solar battery (the amount of energy the battery can use before it needs to be recharged) is reduced by 30-50%.

Batteries are inexpensive, reliable and relatively tolerant to overcharging. However, they must be adequately ventilated to allow gases to escape and should always be stored in an upright position. Vertical storage is necessary to prevent electrolyte leakage, which makes storage of these batteries impractical in certain environments. This type of battery also requires more maintenance and has a shorter service life than other types of batteries.

Sealed lead-acid batteries

Valve-regulated lead-acid batteries (VRLA) are often referred to as sealed lead-acid batteries (SLA). Lead-acid batteries are subdivided into water-filled and sealed lead-acid batteries. Sealed lead-acid batteries store 10-15% more energy than lead-acid batteries and can be charged four times faster.

One of the advantages of lead-acid batteries is that they are much cheaper than other types of batteries. However, the disadvantage is that they have a shorter life span and require more regular maintenance to function properly.

Lithium-ion batteries

Lithium-ion batteries are the most expensive of the solar battery options, but they last four times longer than lead-acid batteries and are much lighter. Owners of boats, trucks or RVs often use them because of their light weight.

Lithium batteries are a relatively new option compared to lead-acid batteries. The latest type of lithium battery is known as lithium iron phosphate (LiFePO4). These lithium-iron-phosphate batteries are often used in deep-cycle battery applications, such as emergency power systems and solar power banks.

These batteries are 30% lighter than flooded batteries and have a good usage efficiency of 80-100%. Lithium-ion batteries also offer the fastest recharge rate and extremely long life of the three deep-cycle options.

Lithium-ion batteries also provide better and more stable voltages at each discharge rate. This means that a lithium-ion-powered lamp will not slowly dim as the battery discharges. Instead, these lights will simply turn off when no more power is available.

Many consider the deep-cycle lithium battery to be the best choice because it is lightweight, small and maintenance-free. It also has excellent usability, fast charge times and a stable, reliable voltage. Despite their many advantages, deep-cycle lithium batteries have the disadvantage that they tend to be much more expensive than other options, such as lead-acid batteries. They also typically require a battery maintenance system (BMS) to monitor the safety and condition of the battery.

What to consider when choosing a battery for a solar array

There are several factors to consider when purchasing a deep cycle battery for a solar system: price, capacity, voltage and lifetime.

Price: Batteries range in price from $100 for the cheapest lead-acid batteries to $1,500 for lithium-iron batteries. Look at the lifespan, not just the initial cost, as lead-acid batteries are more likely to need replacement than lithium-iron batteries. Also, with lead-acid batteries you will have to do more maintenance and we all know that time means money.

Capacity: The capacity of a battery is important because it measures the amount of energy it can store. If you need to power certain devices for a longer period of time, you will need more battery capacity to support a larger load. Capacity is measured in total ampere hours.

Voltage: Check the voltage of the battery pack to make sure it is compatible with the panels and the rest of the system, especially the solar panels. Battery panels are usually available in 12V and 24V versions. Most caravans and boats use 12V battery packs, so people tend to use 12V panels. The advantage of a higher voltage battery pack is that you save money in the long run, as you need fewer charge controllers and can use thinner cables to get the same amount of power. If your power needs are greater than 3KW, opt for a 48V system. Large off-grid homes typically use 48V.

Cycle time: indicates the number of charge and discharge cycles a battery can complete before its capacity drops below its rated capacity. This varies considerably between technologies and is measured in terms of number of cycles.

Which deep cycle battery is best for me?

Flooded lead acid - cheap but high

Maintenance costs: approx. 100 USD

Flooded lead-acid batteries are the cheapest, but they also require the most maintenance. The water level should be checked with a hydrometer and topped up every month to replenish the water level. Lead-acid batteries should be stored in a ventilated room, as they emit gases. This is not necessary for lithium-ion batteries.

Sealed lead-acid (frosted glass and absorbent gel). Low maintenance, low rates.

Cost: $239 - $449.

AGM and gel batteries from Renogy stores.

Unlike flooded lead-acid batteries, sealed lead-acid batteries require little maintenance and are hermetically sealed. They are more expensive than water-filled lead-acid batteries, but also have a longer service life. Within the family of sealed lead-acid batteries there are two types: AGM (Absorbent Glass Mat) and gel batteries.

Gel batteries, which use silica to harden the electrolyte solution, tend to have lower charge and power ratings than absorbed glass batteries. They also cannot absorb as much current, which means they take longer to recharge. However, gel batteries have a longer life than AGM batteries and can be installed in any orientation. Absorption ground glass batteries offer a better temperature range and are slightly less expensive than colloidal batteries.

Lithium iron phosphate: expensive, but maintenance-free and long-lasting.

Cost: $499 to $1499.

Buy from Renogy

Lithium iron phosphate batteries are the most expensive option, but have extremely long life, high discharge and recharge rates, and are very compact and lightweight. They also require very little maintenance.

Lithium batteries typically have a life of at least 10 years. Lithium-iron batteries also lose less capacity when left idle. This is especially useful if solar power is only used occasionally. They also have the best service life in deep-cycle batteries, providing about 2000 cycles at 100% DoD (depth of discharge).

Do lithium batteries charge faster than lead-acid batteries?

Yes, as mentioned above, LiFePO4 batteries are more efficient and have faster recharge times. This is because they can typically handle higher currents, which means they can charge faster than sealed lead-acid batteries. Lead-acid batteries can only handle a limited amount of charging current, mainly because they can overheat if they are charged too quickly.

How many deep cycle batteries do I need?

The number of batteries you need depends on the amount of electricity you consume. Electricity consumption is measured in kilowatt hours. For example, if you need 1,000 watts of power per day for 8 hours per day, your power consumption is 8 kWh. Between 4 and 8 kWh of battery capacity is usually sufficient to meet the average needs of a family of four.

To determine the system size that best suits your needs, we recommend that you make a list of all the devices you want to support. Find out the performance data, i.e. the amperage and voltage values of your products and indicate the average run time of each device. Renogy's solar panel calculator is a great tool that will allow you to quickly and easily determine your specific needs.

Can I connect different types and sizes of deep cycle batteries?

We recommend connecting batteries of the same type and amp-hour capacity, i.e. if you are using absorbent fiberglass cells, all cells in your battery bank should be AGM cells. This will reduce the loss of performance caused by different cells.

Are solar cells safe?

Yes, in general, solar cells are very safe. Problems can arise if they are not installed correctly or if the cells are of poor quality. Therefore, it is important to install the batteries correctly and to buy them from a reputable manufacturer.

Lithium-iron phosphate batteries have a slightly higher risk of overheating than other batteries if they are not installed correctly or are supplied by an unreliable manufacturer. However, in most cases, lithium-iron batteries pose little risk to vehicle owners.Renogy's deep cycle solar batteries are equipped with a BMS, which stands for Battery Management System.The BMS safely protects the battery from being used/charged under improper conditions. In addition, a 12V battery charger improves the safety and performance of the solar cell. 

How long does it take to charge a deep cycle battery?

The total charging time depends on weather conditions as well as the condition and type of battery. When the battery is fully discharged, the panel can be charged in five to eight hours.

The total charging time depends on the condition of the battery. When the batteries are fully discharged, the solar panels can power them within five to eight hours. The position of the sun in the sky affects the rate at which the panels charge. If the sun falls directly on the panel in midsummer, the charging speed will be faster. On cloudy days, the charging cycle will be slower.

What is the life expectancy of a deep cycle battery?

Battery life varies depending on the technology. For example, many colloidal cells typically last 1,100 cycles, absorber glass 600 cycles, and lithium iron phosphate 7,000 cycles. The total lifetime of a solar cell can be assumed to be between 5 and 15 years. Therefore, the battery should be replaced at least once during the lifetime of the solar system.

Although many people focus on the performance of the solar panels when planning a solar installation, it is important to remember to spend time considering the different battery options. After all, a faulty or underperforming battery can affect the overall performance of your solar system, costing you thousands of dollars in the long run.

Summary

With so many deep-cycle battery options available, deciding on the right solar storage solution can be a challenge. Flooded lead-acid, sealed lead-acid and lithium-iron batteries all have their advantages, from maintenance requirements to longevity and recharge time. There is no one-size-fits-all solution, but by weighing these costs and benefits, you can create the battery pack that best suits your needs.