Sealed lead acid battery

sealed lead acid battery

Are you curious about sealed lead acid battery and their various types? If so, you’ve come to the right place. This comprehensive guide will delve into the world of sealed lead acid batteries, exploring their types, advantages, cycle life, temperature range, float voltage, and applications. This article will provide you with the knowledge you need to understand and appreciate sealed lead acid batteries.

What is a sealed lead acid battery?

A sealed lead acid battery, also known as a valve-regulated lead acid (VRLA) battery, is a type of rechargeable battery. Unlike flooded lead acid batteries, which are commonly found in their liquid form, sealed lead acid batteries are sealed with an immobilized electrolyte. This sealed design offers a range of benefits and advantages over traditional flooded batteries.

In a sealed lead acid battery, the hydrogen gas produced during the charging process is reabsorbed into the electrolyte, preventing excessive pressure buildup. This eliminates the need for regular top-ups of distilled water, as there is minimal electrolyte loss. However, it requires more precise charging controls to manage hydrogen production effectively.

Sealed lead acid batteries are widely used in various applications, including automotive, marine, RVs, and backup power systems. Now, let’s explore the different types of sealed lead acid batteries available in the market.

Types of sealed lead acid battery

There are two primary types of sealed lead acid batteries: Absorbed Glass Mat (AGM) batteries and Gel Cell batteries. Both types offer unique features and characteristics that cater to specific applications.

1. Absorbed Glass Mat (AGM) Battery

AGM batteries are a popular choice for a wide range of applications due to their superior performance and durability. In an AGM battery, the electrolyte is absorbed into fiberglass mat separators between the battery plates. This design provides several advantages, including:

  • Maintenance-Free: AGM batteries are maintenance-free, eliminating the need for regular electrolyte top-ups.
  • Leak-Proof: The sealed design of AGM batteries prevents electrolyte spillage, making them safe to use in various orientations.
  • Position Insensitive: AGM batteries can be installed in any position, offering greater flexibility compared to flooded batteries.
  • Low Self-Discharge Rate: AGM batteries have a low self-discharge rate, ensuring better charge retention over extended periods.

AGM batteries are commonly used in automotive applications, such as starter batteries and deep cycle batteries for marine vehicles, RVs, and golf carts.

2. Gel Cell Battery

Gel Cell batteries, also known as gel batteries, feature a unique electrolyte composition suspended in a silica gel. This gel-like substance allows electrons to flow between the battery plates while preventing leakage. Gel Cell batteries offer the following advantages:

  • Vibration Resistance: Gel batteries are highly resistant to vibrations, making them ideal for off-road and rough terrain vehicles.
  • Deep Discharge Tolerance: Gel batteries can withstand deep discharges without significant damage, making them suitable for deep cycle applications.
  • Longer Cycle Life: Gel batteries have a longer cycle life compared to AGM batteries, making them a reliable choice for continuous use.

However, it’s important to note that gel batteries are more sensitive to overcharging. Overcharging can irreversibly damage the gel and reduce the battery’s overall lifespan. Therefore, gel batteries are not as commonly used in automotive applications as AGM batteries.

Cycle life of the sealed lead acid battery

The cycle life of sealed lead acid (SLA) batteries is an important factor to consider when assessing their suitability for specific applications. It refers to the number of charge and discharge cycles a battery can undergo before its capacity significantly decreases. Understanding the cycle life helps determine the longevity and reliability of SLA batteries in various use cases.

On average, SLA batteries can provide anywhere from 200 to 600 cycles, depending on several factors. Here are some key factors that can affect the cycle life of sealed lead acid batteries:

  • Depth of Discharge (DOD): The depth has a significant impact on its cycle life. Generally, shallow discharges (discharging the battery partially) tend to prolong the battery’s life, compared to deep discharges (discharging the battery almost completely). It is recommended to avoid deep discharges whenever possible to extend the cycle life of SLA batteries.
  • Charge Voltage: Charging the battery at the correct voltage is crucial for maintaining its cycle life. Overcharging or undercharging can lead to premature capacity loss and reduce the number of cycles the battery can undergo. Follow the manufacturer’s recommended charging voltage.
  • Temperature: The operating temperature significantly affects the cycle life of SLA batteries. Extreme temperatures, both high and low, can accelerate capacity loss and reduce the overall cycle life. It is important to operate SLA batteries within the recommended temperature range, typically between -20°C (-4°F) and 50°C (122°F), to maximize their cycle life.
  • Maintenance: Proper maintenance practices can also impact the cycle life of sealed lead acid batteries. Regularly checking the battery’s electrolyte levels (for flooded lead acid batteries), ensuring proper ventilation, and keeping the battery clean can contribute to extending its cycle life. Additionally, following the manufacturer’s guidelines for maintenance can help optimize the battery’s performance and prolong its cycle life.
  • Battery Design and Quality: The design and build quality of SLA batteries can vary among manufacturers. Opting for batteries from reputable brands that adhere to quality standards can ensure better cycle life and overall performance. It is advisable to research and select batteries with a proven track record of reliability and longevity.

Temperature Range

SLA batteries have specific temperature limits that should be adhered to ensure optimal functioning. It can be categorized into the following key points:

  • Recommended temperature range: SLA batteries typically have a recommended temperature range of -20°C (-4°F) to 50°C (122°F). This range signifies the temperatures at which the batteries can function efficiently without significant performance issues
  • Impact of low temperatures: Operating SLA batteries below the lower limit of -20°C (-4°F) can have adverse effects. At extremely low temperatures, the chemical reactions within the battery slow down, leading to reduced capacity and decreased power output. The battery may struggle to provide the necessary energy, resulting in potential disruptions in performance.
  • Impact of high temperatures: Exceeding the upper limit of 50°C (122°F) can also be detrimental to SLA batteries. High temperatures accelerate chemical reactions and can cause increased self-discharge rates. This leads to decreased overall capacity and a shortened battery lifespan. Additionally, excessive heat can result in physical damage to the battery, such as deformation or electrolyte leakage, rendering it unusable.
  • Effect of temperature fluctuations: Temperature fluctuations within the recommended range can impact SLA batteries. Rapid temperature changes can subject the battery to thermal stress, affecting its performance and longevity. Minimizing temperature fluctuations and maintaining a stable operating environment are crucial for optimal battery function.

Float voltage 

The float voltage is a critical parameter for the proper charging and maintenance of sealed lead acid (SLA) batteries. It varies depending on the battery’s nominal voltage. It refers to the voltage at which the battery is maintained during standby or float charging periods. Here are sealed lead acid battery voltage charts for 6V, 12V, and 24V batteries.

Battery VoltageFloat Voltage RangeNominal Capacity (Ah)

Note: The nominal capacity (Ah) of SLA batteries can vary depending on the specific battery model or manufacturer. It is important to refer to the manufacturer’s specifications for the exact nominal capacity of the SLA battery you are using

Applications of sealed lead acid battery

sealed lead acid battery

Sealed lead acid batteries find applications in a wide range of industries and sectors due to their reliability, versatility, and cost-effectiveness. Let’s explore some of the common applications:

Automotive Applications:

  • Automotive Starting Batteries: Provide the initial power to start the engine
  • Backup Power for Automotive Accessories: Ensure continuous operation even when the engine is off
  • Electric Vehicles (Low-Power): such as golf carts, electric scooters, and electric wheelchairs

Home and Household Applications:

  • Uninterruptible Power Supply (UPS): Provide electricity during power outages to essential appliances and devices.
  • Emergency Lighting: Provide backup power for emergency lights and exit signs during power failures
  • Portable Power: such as camping equipment, portable lighting, portable tools, and portable electronics

Industrial and Commercial Applications:

  • Telecommunications: Include cell towers, base stations, and communication equipment, ensuring
  • Alarm and Security Systems: Ensure continuous operation even during power failures
  • Medical Equipment: Include portable medical devices, patient monitoring systems, and backup power for critical medical instruments
  • Solar Energy Storage: Store the energy generated by solar panels for use during non-sunlight hours
  • Marine and RV Applications: Power onboard electronics, lighting, and auxiliary equipment


Sealed lead acid batteries are a versatile and reliable power solution widely used in automotive, residential, and industrial applications. Whether you’re looking for a dependable starter battery for your vehicle or a backup power solution for your home, sealed lead-acid batteries are an excellent choice. By understanding the different types, applications, and benefits of sealed lead acid batteries, you can make informed decisions and ensure optimal performance and longevity.

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