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A 12-volt car battery is not as straightforward as one might think. Yes, all car batteries power your car, but not all car batteries are the same. There are conventional lead-acid batteries, gel batteries, and the newest kid on the block, AGM batteries.

AGM batteries are designed to prevent the common danger of spillage that is possible with conventional batteries. As the battery ages, the sulphuric acid and water solution inside can seep out and spill over the garage floor, in your engine compartment, or onto you, and that’s not ideal. AGM batteries fix that in a number of ways, but how do they compare with conventional lead-acid batteries? How do they work, and is an AGM battery right for you? 

Understanding the difference between AGM batteries and conventional lead-acid batteries goes beyond spill-proofing and voltage. And picking the right AGM battery for your particular use, whether it’s warranted for your ride or not, can be somewhat challenging if you don’t know the ins and outs of battery chemistry. So stick with Car Bibles as we decode the language of AGM batteries. 

What Is an AGM Battery and How Does It Work?

AGM stands for “absorbent glass material.” It’s a type of car battery that uses minuscule glass fibers to suspend the battery’s electrolyte mixture of sulphuric acid and water. This allows the solution to be more evenly distributed across the battery’s active lead plates and prevents sloshing, which is a common issue among conventional lead-acid batteries. 

What’s the Difference between AGM Batteries and Conventional Car Batteries

The biggest difference between a conventional car battery and AGM battery is how each treats the electrolyte solution. Your average lead-acid car battery has an unobstructed, free-flowing fluid that makes them very easy to maintain and to produce. And as described above, AGM batteries suspend the solution within the glass material. This manufacturing makes it more stable and power-dense but more expensive to purchase and maintain. 

What’s the Difference between AGM Batteries and Gel Batteries

As you might expect, there are also differences between AGM and gel batteries. Whereas the AGM battery suspends the electrolyte solution with a glass material, gel batteries use silica to form a gel-like substance. Both battery’s respected compositions are aimed at preventing the sulphuric acid and water solution from spilling out and hurting the user, destroying the area around it, or contaminating the ground.

Are There Any Downsides to AGM Batteries?

There are a couple of downsides to AGM batteries one must consider. As with other batteries, AGM batteries are susceptible to diminished charging over time. It’s less than other battery chemistries, but the physical laws of the natural world cannot be changed. Furthermore, these batteries are sensitive to both over/under-charging, which can reduce the battery’s lifespan. The biggest downside for the customer might be the high price. 

Are AGM Batteries More Expensive Than Conventional Batteries?

Yeah, they are. AGM batteries typically cost about twice that of conventional lead-acid batteries. However, they’ll hold a charge longer than conventional batteries and, as mentioned previously, are designed to reduce the chances of spillage and sloshing. So you get what you pay for if you do decide to make the switch. 

How Many Years Do AGM Batteries Last?

The common wisdom behind conventional battery life says that they’ll last about three to five years. Of course, there are exceptions, plus your continued maintenance and how you treat your battery will play factors in longevity. AGM battery manufacturers such as Optima and Interstate, however, state that AGM batteries are designed to last two to three times longer, or six to 15 years, again, depending on your maintenance and how you use it. 

TL;DR: Your mileage will vary, and you play an important factor in your battery’s life and longevity.

Does an AGM Battery Require a Special Charger?

You betcha. As AGM batteries are designed differently than conventional batteries, have different workloads, different chemistries, and uses, they do have special charging requirements. As such, you’ll need a different charger because you can actually damage an AMG battery with a non-AGM battery charger. In other words, we absolutely recommend you purchase an AGM-specific battery charger

What Should I Consider When Buying a Replacement Battery?

Your vehicle comes with very specific battery needs. Keeping it charged and able to turn the engine over in cold weather, or in hot, is obviously important, and you should follow the guidelines set out by the vehicle’s manufacturer in your dusty manual stuffed in the back of your glovebox. 

If you don’t do that, you run the risk of stranding yourself in the middle of nowhere with Deliverance playing in the background. Likewise, you can also visit your local auto parts store and look up the exact make and model of battery your car used, as well as other batteries that share performance stats. You can also call the dealership to find out which battery your car takes, though they might try to upsell you on something you don’t need.

FAQs About AGM Batteries

Car Bibles answers all your burning questions.

Q. How can you tell if a battery is an AGM battery?

A. It’ll say “AGM” or “Absorbed Glass Mat battery” on the side of the battery. You can also search online for your make and model. 

Q. Are AGM batteries deep cycle?

A. Yes, AGM batteries file into a class of deep-cycle batteries. A deep-cycle battery is a battery that’s designed to continue providing electricity even when it’s almost fully depleted, around 80-percent of its capabilities. 

Q. Do AGM batteries work with solar panels?

A. AGM batteries are actually better for solar panels than standard batteries as they’re better for storing electricity for longer periods of time and have the aforementioned deep-cycle capabilities. 

Q. Can you jump-start an AGM battery?

A. You absolutely can. Most jumpstarters are actually AGM batteries themselves while using a conventional battery with the same voltage won’t do any damage to the AGM battery.

Learn More About AGM Batteries From This Helpful Video

Car Bibles’ editors understand that not everyone is a text-based learner. For those kinesthetic people out there, we have your back with a video showing you exactly what an AGM battery is. We pulled it from one of our favorite, and most trusted, sources and it’s a great additional resource.

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