What is an AGM Battery and How Does It Work?
Driving in the present day is vastly different from how it was back in 1973.
● Dashboards now feature touch screens.
● Seat belts that tighten automatically.
● The ability to start a car remotely.
● Starting your vehicle via your smartphone.
● Backup cameras and collision warning sensors.
● Connections for satellite radio, Wi-Fi, and Bluetooth.
● Seat warmers are wonderful.
● Auto start - stop engines that enhance fuel efficiency to over 30 - 40 mpg by shutting off the engine instead of letting it idle, and can restart it whenever you're ready to move.
All these technologies depend on electricity. Some even need electricity when the engine is not running.
This demand is an enormous burden that a standard car battery cannot manage. They used to be suitable for cars because they could supply a large amount of electricity to a starter in a short burst. Since the lead-acid battery was invented in 1859, its design has undergone only minor adjustments and the use of a durable plastic case to protect the lead plates and hold the sulfuric acid and water.
A battery design from the 1800s can't fully meet the needs of today's vehicles.
A new generation of car batteries is needed.
Here comes the absorbed glass-mat (AGM) battery. AGM batteries are car batteries made to provide a high amperage even when the engine is turned off. They are also rapidly becoming one of the most prevalent types of batteries on the roads.
Due to their electrical power requirements, more than half of the new vehicles sold after 2019 need an AGM battery. As of 2022, there are more than 50 million vehicles on the road that require an AGM battery.
What is an AGM battery, and what sets it so apart from a regular flooded car battery?
What is an AGM Battery?
An AGM battery is a type of sealed lead-acid battery where the electrolyte (the liquid that helps conduct electricity) is absorbed into a fiberglass mat separator rather than being stored in free liquid form. This mat holds the electrolyte in place, which significantly reduces the risk of spillage or leaks, making AGM batteries much safer than traditional flooded batteries.
The AGM technology was first developed for military and aviation applications due to the need for batteries that could withstand vibrations and extreme conditions. Today, AGM batteries are commonly found in automotive applications, particularly in vehicles with advanced electrical systems, including start-stop systems, hybrid vehicles, and high-performance cars.
How Does an AGM Battery Work?
AGM batteries function much like traditional lead-acid batteries but with some key differences. Here’s how they work:
1. Electrolyte Absorption: In a typical lead-acid battery, the electrolyte is a liquid solution of sulfuric acid and water. In an AGM battery, the electrolyte is absorbed into a fiberglass mat, which is placed between the positive and negative plates. This mat holds the electrolyte in place, preventing it from sloshing around and causing leakage.
2. Sealed Design: AGM batteries are sealed, meaning they do not require water topping up like flooded lead-acid batteries. The sealed design also makes AGM batteries maintenance-free, unlike traditional flooded batteries, which require periodic checks and refills.
3. Valve-Regulated: AGM batteries are valve-regulated, meaning they are designed to release any gas build-up through a vent valve. This design prevents overcharging and helps maintain a stable internal pressure, which makes AGM batteries safer and more efficient.
4. Recombination of Gases: AGM batteries can recombine hydrogen and oxygen gas that is produced during charging, making them "closed-loop" batteries. This process helps prevent the loss of water, ensuring that the battery remains sealed and maintenance-free.
5. Faster Charging: AGM batteries typically charge faster than flooded batteries. The tightly packed internal components and the high surface area of the plates allow for efficient charging, which is especially beneficial for modern vehicles with advanced electrical systems.
Advantages of AGM Batteries
AGM batteries offer several key benefits that make them a popular choice for automotive and other applications:
● Improved Durability: AGM batteries are designed to withstand vibrations, making them more durable than traditional flooded batteries. This makes them ideal for vehicles with rough handling or constant vibrations, such as trucks, boats, and off-road vehicles.
● Longer Lifespan: AGM batteries generally have a longer lifespan than flooded lead-acid batteries. Their sealed design prevents the electrolyte from evaporating, which can lead to premature battery failure in flooded batteries.
● Better Performance in Extreme Conditions: AGM batteries can perform better in extreme temperatures compared to traditional batteries. They are less likely to freeze in cold weather and can handle high heat conditions, which makes them a great choice for both cold and hot climates.
● Faster Charging and Higher Efficiency: AGM batteries charge more quickly than flooded batteries, making them ideal for vehicles with high electrical demands. The faster charging times can be particularly beneficial in vehicles with start-stop systems or those with advanced technology.
● Maintenance-Free: One of the biggest advantages of AGM batteries is that they are maintenance-free. Unlike flooded batteries, they do not require periodic water refilling or checking the electrolyte levels, making them much easier to maintain.
Applications of AGM Batteries
AGM batteries are used in a wide range of applications, from cars to boats and beyond. Some common uses include:
● Automotive Applications: AGM batteries are commonly used in modern vehicles, especially those with start-stop systems, hybrid vehicles, and high-performance cars. They are designed to handle the increased power demands of these vehicles' electrical systems.
● Marine and RV Use: AGM batteries are well-suited for use in boats and RVs due to their ability to withstand vibrations and their sealed design, which makes them more reliable in wet and harsh conditions.
● Solar Power Storage: AGM batteries are used in solar energy systems to store power generated by solar panels. Their deep-cycle capabilities and ability to handle regular charging and discharging make them ideal for off-grid solar systems.
● UPS Systems (Uninterruptible Power Supply): AGM batteries are used in backup power systems for homes and businesses to provide emergency power during outages.
VDIAGTOOL BT500: Your Solution for Checking AGM Batteries
While AGM batteries are low-maintenance, they still need regular checks to avoid unexpected failures—especially since a dead battery can leave you stranded. To accurately assess your AGM battery's condition (and that of your vehicle's electrical system), you need a reliable testing tool.
That's where the VDIAGTOOL BT500 Battery Tester comes in. Designed specifically to handle AGM batteries (and other common types like VRLA, GEL, and EFB), this tool takes the guesswork out of battery maintenance—whether you're a DIY driver or a professional mechanic.
Key Features of the VDIAGTOOL BT500
● Wide Compatibility: Works with 6V-32V batteries, including AGM, VRLA, GEL, and EFB models. It's suitable for cars, trucks, and motorcycles, covering nearly all vehicles that use AGM batteries.
● Battery testing: covers battery capacity testing, starting test, and power generation testing, which can accurately understand the capacity, starting performance and power generation of AGM batteries.
●Convenient data storage: The waveform can be printed and replayed, allowing the AGM battery test data to be better preserved for subsequent analysis and viewing.
● Safe & User-Friendly: Equipped with reverse polarity protection, spark-proof clips, and over-temperature/over-voltage safeguards, the BT500 is safe to use even for beginners. Results display directly on the screen, so you don’t need technical expertise to understand them.
FAQs About AGM Batteries
1. Does my car have an AGM battery? Do I need one?
Most modern cars (2015 or newer) come with AGM batteries—especially if they have start-stop systems, hybrid powertrains, or advanced electrical features (like built-in navigation or multiple USB ports). If your car is older (pre-2015) or has a basic electrical system, it may use a traditional flooded battery.
You need an AGM battery if your vehicle's manual specifies it—using a traditional battery in an AGM-designed system can cause electrical damage (e.g., overcharging) or shorten battery life. If you're unsure, check your owner's manual or look for labels on your current battery (terms like "AGM" or "Absorbent Glass Mat" will be printed clearly).
2. How do I confirm if my car has an AGM battery?
There are 3 easy ways to check:
● Check the battery label: Look for AGM, Absorbent Glass Mat, Sealed, or Maintenance-Free printed on the battery case (usually on the top or side).
● Consult your owner's manual: The "Battery" section will specify the type required for your vehicle.
● Use a compatible tester: Tools like the VDIAGTOOL BT500 can detect battery type automatically during testing—just connect it to your battery, and it will identify if it's AGM.
