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What are SLA batteries?

SLA batteries, also known as Valve Regulated Lead Acid, (VRLA) batteries are rechargeable batteries composed of lead plates and sulfuric acid. They are designed to seal in electrolytes and provide electrical energy. SLA batteries offer secondary or backup power to a wide range of essential systems and equipment, from emergency lighting systems and video surveillance to fire alarm systems and access control.

SLA batteries have been around for over 160 years and carry numerous benefits including durability, cost-efficiency and longevity. Their vast range of availability, minimal maintenance requirements and safety features have made them a preferred choice for a power solution for many years.

Construction and features

SLA batteries are manufactured to be maintenance-free due to their sealed lead construction, which prevents acid and gases from leaking out. This eliminates the need to add electrolytes or water regularly – saving installation and maintenance time. However, it's worth noting that while SLA batteries are generally maintenance-free, regular monitoring of their condition is still recommended.

SLA batteries are usually bulkier and heavier than traditional batteries because of their lower energy density. You'll want to take their size into account when installing in areas where space is limited.

Although SLA batteries are known to be leak-proof, they do feature an emergency pressure release system. When gas buildup occurs due to extreme over-charging, and it reaches critical levels within the battery, a small pressure release valve is activated. This safety vent regulates and releases gas pressure, safeguarding against potential battery damage. All SLA batteries come with a small pressure release valve.

Different types of SLA batteries and applications

SLA batteries offer remarkable versatility, making them suitable for a wide range of projects, from small-scale residential installations to large commercial jobs. When selecting an SLA battery, it's essential to consider the different types of battery and its applications. There are three main types, each with distinct features.

General Purpose Batteries

General purpose SLA batteries are commonly used in a variety of applications due to their reliability. They are frequently used in emergency lighting systems, including exit signs and lights for critical emergencies. Additionally, they are utilized as a UPS battery backup for small businesses, residential sump pumps and security systems such as surveillance cameras, fire alarm control panels and access control systems. When the main power supply is interrupted in such areas, the SLA battery takes over, allowing users to still gain access to secured areas.

General purpose SLA batteries are affordable, easily rechargeable, have a wide temperature range and can be stored for extended periods, making them adaptable in both residential and commercial applications.

Deep Cycle Batteries

Deep cycle SLA batteries are specifically designed to provide consistent power over a longer period than general purpose SLA batteries. The term "Deep Cycle" means that they can handle deep discharges of 80 to 100%. The Depth of Discharge (DoD) can tell you how much of the battery capacity is being utilized. Their design is typically smaller in size than regular SLA batteries and has thicker lead plates to generate more electricity in the battery. This helps with handling deep discharges over time which keeps equipment running all day long.

Deep cycle SLA batteries are ideal for applications that require sustainable power output. Deep cycle SLA batteries are useful for remote monitoring systems in locations with limited access. Additionally, they provide uninterrupted service to UPS systems, ensuring continuous power for equipment like computers, servers and communication systems.

High-Rate UPS Batteries

Engineered with thinner cell plates than deep cycle batteries, high-rate UPS batteries deliver high bursts of power for short durations, making them suitable as starter batteries for emergency situations. High-rate UPS batteries serve as a quick solution in situations where sudden power disruptions occur, preventing data loss and preventing production downtime or safety hazards. These batteries provide backup power for applications including fire alarm systems, surveillance cameras, UPS systems for data centers, medical emergency equipment, data comm and networking devices such as network switches and routers.

This battery type can help your customers save time and money by preventing costly equipment damage and business disruption. High-rate UPS batteries also have a lifespan of up to ten years, which is longer compared to other SLA batteries.

Care and maintenance

With proper maintenance, SLA batteries can last for years. However, there are charging mistakes users can make that can leave the battery defective. As an installer, it is essential to follow good charging practices to prolong the battery's health. Here are a few tips to keep in mind:

• Always store the battery fully charged to avoid complete depletion over time.
• Avoid leaving the battery fully discharged for an extensive period, as this can result in capacity loss or damage for some SLA batteries. However, this rule does not apply to deep cycle SLA batteries, as they are designed to withstand multiple deep cycles.
• Avoid overcharging the battery, as it can lead to overheating and shorten the battery's life or damage it. 
• When charging your SLA battery, always make sure to match the correct battery charger's voltage and current to the voltage of the battery you are charging to avoid battery failure.

When to replace an SLA battery

Most SLA batteries have a lifespan of three to five years (300-500 cycles), which can vary depending on factors like charging methods, environment, applications and battery quality. Recognizing when to replace an SLA battery for your customers is crucial to prevent equipment service disruptions. Here are some common signs to watch for: 

• Inability to hold a charge for an extended period
• Rapid drop in voltage levels
• Physical damage, such as bloating or swelling, which indicates overcharging and will require immediate replacement

Once an SLA battery has reached the end of its lifespan, it is considered hazardous waste. So, what is the correct method for disposing of it? Because SLA batteries contain lead, it's best to recycle them in accordance with local guidelines and regulations to reduce their environmental impact.

Overall, SLA batteries provide reliable backup power for various applications, offering versatility, quality performance, durability and longevity. By understanding their types, construction and maintenance practices, you can successfully utilize SLA batteries in your projects and ensure uninterrupted service for your customers.