A car battery is not as straight-forward 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 very common, and dangerous, issue of spillage found in conventional batteries. As the battery ages, the sulphuric acid, water solution inside can seep out and spill over the garage floor, in your engine compartment, or onto you. None of those are ideal. But is an AGM battery right for you?

Understanding the difference between AGM batteries and conventional lead-acid batteries goes beyond spill-proofing and voltage, though. 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” and an AGM battery is a 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.

AGM Batteries vs. Conventional Car Batteries

The biggest difference between conventional car batteries and AGM batteries is how each treats the electrolyte solution. Your average lead-acid car battery has an unobstructed, free-flowing fluid. As described above, AGM batteries suspend the solution within the glass material.

What is an AGM Battery?

AGM Batteries vs. Gel Batteries

There are also differences in AGM vs. gel batteries. Whereas the AGM battery suspends the electrolyte solution with the 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 either hurting the user or contaminating the ground.

Are There Any Downsides to AGM Batteries?

There are a couple downsides to AGM batteries one must consider, including diminished charging over time and sensitivity to over/under-charging.

Are AGM Batteries More Expensive Than Conventional Batteries?

They are. AGM batteries typically cost about twice that of conventional lead-acid batteries. However, they last longer than conventional batteries.

How Many Years Do AGM Batteries Last?

Conventional batteries are designed to last between 3-5 years. AGM battery manufacturers such as Optima and Interstate, however, say AGM batteries could last between 2-3 times longer, or 6-15 years.

Does an AGM Battery Require a Special Charger?

Yes, AGM batteries are designed differently than conventional batteries and thus have special charging requirements. 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.


  1. AGM Battery – Battery University
  2. AGM Battery – Interstate Batteries