AGM Batteries: The Smarter Choice for Modern Cars
Automotive technology has advanced at a rapid pace, yet the 12-volt battery under the hoods of our gas-powered cars remains relatively stagnant. This isn’t the battery pack in an electric vehicle, but the lead-acid battery that starts your combustion engine and powers basic electronics when the engine is off. While newer lithium-ion batteries offer performance advantages, they are expensive and can struggle in cold temperatures. The best solution in the interim is what’s called an Absorbed-Glass Mat Battery (AGM). It enjoys the reliability of a lead-acid battery while presenting impressive performance at a reasonable price.
How AGM Batteries Work
Lead-acid batteries, invented in 1859, are still in use today but have undergone various changes over the years, and the Absorbed Glass Mat (AGM) battery is one such evolution. These batteries function using lead plates submerged into diluted sulphuric acid to sustain a controlled chemical reaction. This creates a negative charge at the negative terminal and the opposite for the positive terminal. When the battery isn’t in use, the electrons inherently want to move back to the positive side. They can only flow through a completed circuit, which allows them to move where they want to go when connected to a device that needs power.
The Difference Between Wet-Cell and AGM Batteries
All car batteries use lead-acid chemistry, but there are different varieties. The “legacy” batteries are called wet-cell batteries. Newer vehicles with sophisticated electrical systems have higher electrical demands, making AGM batteries almost a necessity.
Conventional wet-cell batteries use lead plates submerged in an electrolyte solution, or battery acid. Each battery has six cells that produce 2.1 volts each. AGM batteries are a more modern take on the lead-acid battery. They use ultra-thin fiberglass mats to absorb the battery acid instead of submerged plates, making the batteries spill-proof. The thinner mats allow more acid to contact the lead plates, and manufacturers can pack more plates into the same space, making AGMs more energy-dense than wet-cell batteries. This is particularly beneficial in newer vehicles with features such as start-stop systems and more onboard screens.
AGM vs. Lithium-Ion Batteries
Lithium-ion batteries have often been discussed as an option for automotive applications, but they have yet to gain widespread adoption. They’re incredibly expensive and offer only marginal benefits over AGM batteries. For example, let’s compare two batteries for a Volkswagen GTI:
- Interstate Batteries 12V H6 AGM Battery: Around $275 to $380, and can supply 950 cranking amps.
- Antigravity H5 Lithium Car Battery: Around $720, and can supply 1500 cranking amps.
The Advantages of AGM Batteries
Here are some key benefits of AGM batteries:
- Deep Cycle Applications: AGM batteries can be drained to 50% capacity before requiring recharging. This is particularly useful in winter, when cars sit idle. They maintain similar performance levels despite deeper discharge.
- Recyclable: Almost all components can be recycled, with recycling centers sorting batteries by type and chemistry, shredding and melting the solids for reuse, while safely disposing of the remaining liquids and other toxic materials.
- Durability: Initially designed for military aircraft, AGM batteries are built to last. They’re spill-proof and vibration-resistant and are a popular choice for race cars and boats.
The Disadvantages of AGM Batteries
- Expense: AGMs are more costly than wet-cell batteries, though they are still a less expensive option than lithium-ion.
- Overcharging Resistance: Although AGMs are excellent, their overall performance is noticeably lessened when subjected to overcharging.
Which Battery Should You Choose?
Given the above advantages, the best course of action is to buy a like-for-like replacement for the battery that your car came with. Thankfully, it is pretty easy to verify what kind of battery you have. The label on an AGM battery will typically say “AGM.” You can also examine the model number on the manufacturer’s website. Ultimately, if you’re looking for enhanced performance and longer life in your car battery, an AGM is a great option.
