Gel, AGM (Absorbent Glass Mat), and Lead Acid batteries are all types of rechargeable batteries commonly used in a variety of applications. While they all store electrical energy, there are significant differences in their construction and performance. In this post, we will explain the key differences between Gel, AGM, and Lead Acid batteries.

Lead Acid Batteries:

Lead Acid batteries are the oldest and most widely used type of rechargeable battery. They have a liquid electrolyte and are constructed with lead plates and lead oxide. Lead Acid batteries come in two main types: flooded lead-acid batteries and sealed lead-acid batteries.

Flooded Lead Acid batteries have a liquid electrolyte that is free to move around the cell. They require regular maintenance, including water top-ups, and must be used in a well-ventilated area. 

Sealed Lead Acid batteries are maintenance-free and have a valve-regulated design that prevents the electrolyte from escaping. They come in two types: AGM and Gel batteries.

AGM Batteries:

AGM batteries are a type of sealed lead acid battery that uses a fiberglass mat separator between the lead plates to hold the electrolyte. The mat is saturated with electrolytes and is designed to hold it in place during use. AGM batteries are maintenance-free and sealed, making them ideal for use in remote locations or in sensitive areas such as hospitals.

Gel Batteries:

Gel batteries use silica gel to immobilize the electrolyte, which is then absorbed by the lead plates. The gel is denser than the liquid in AGM batteries, providing a more stable electrolyte environment. Gel batteries are highly resistant to shock and vibration, making them ideal for use in high-impact environments such as off-road vehicles.

What are the main differences between these batteries?

Gel batteries are the most robust, with a longer lifespan and the ability to withstand high temperatures and rough environments. AGM batteries are lighter and more compact, making them ideal for use in portable devices and small vehicles. Lead Acid batteries are the most widely used and have a lower upfront cost, but require regular maintenance and have a shorter lifespan.

How long do these different batteries last?

To best answer this question, please read our article “Typical cycle life: Gel vs AGM vs Lead Acid vs Lithium 

On average, AGM batteries can last between 3 to 5 years. To ensure the optimal lifespan of an AGM battery, it’s important to perform regular maintenance, such as ensuring the battery is kept clean and dry, checking the voltage regularly, and avoiding overcharging or over-discharging the battery. It’s also important to store the battery in a cool, dry place when not in use to prevent degradation.

AGM batteries are most commonly used in applications where they experience shallow discharges and frequent recharges, such as backup power systems and solar power systems.

Deep cycling an AGM battery can cause several issues, including sulfation, which occurs when lead sulfate crystals build up on the battery plates and reduce the battery’s capacity. Over time, sulfation can become permanent and reduce the battery’s ability to hold a charge. Additionally, deep cycling can cause the battery’s internal resistance to increase, which can lead to reduced capacity and a shorter lifespan.

To avoid damaging an AGM battery through deep cycling, it’s important to monitor the battery’s state of charge and avoid discharging it below a certain level, typically around 50% to 60% of its total capacity. It’s also important to use a battery charger that’s designed to charge AGM batteries and avoid overcharging or undercharging the battery.