When it’s time to replace your battery, the type you choose can significantly impact your vehicle’s performance. The two most common batteries for cars and trucks are the traditional flooded lead acid and Absorbed Glass Mat (AGM). Either kind can be installed in your vehicle, but which one is the right choice for you?
FLOODED LEAD ACID
The traditional flooded lead acid battery dates back to 1859. They became widely used in the 1920s as cars became equipped with electric starter motors. This tried-and-true technology is still the most common battery used in cars and trucks today.
Inside the black box of a traditional 12-volt flooded lead acid battery are six cells, each with a set of positive and negative lead plates. The plates are immersed (or “flooded”) in a sulfuric acid solution, known as electrolyte, which triggers a chemical reaction and produces electrical energy. Sometimes you may notice a powdery white, green, or blue substance around the battery terminals. This corrosion build-up, caused by gasses from the chemical reactions inside the battery, can shorten battery life. Some flooded batteries require venting to allow these gasses to escape.
Depending on driving and climate conditions, flooded lead acid batteries last three to five years. However, road vibration and exposure to extreme heat or cold can reduce the lifespan. Also, when a vehicle is driven, the alternator maintains the battery so it can continue powering the electrical components (e.g., lights, radio, power seats, backup camera, etc.). Therefore, cars and trucks must be driven regularly for the battery to maintain its charge. Most flooded lead acid batteries in good condition will remain charged for at least two weeks without needing the vehicle to be driven.
Pros
• 3-5 year lifespan
• More affordable than AGM
• Mature, reliable, well-understood technology
• High output power capability
Cons
• Adversely affected by extreme temperatures and vibration
• Electrolyte can spill out if the battery case is damaged
• Corrosion build-up that reduces battery life
ABSORBED GLASS MAT (AGM)
AGM batteries were invented in 1980 and were originally used to power military vehicles and aircraft. Today, they are a popular choice for personal cars and trucks.
The interior of the AGM battery is slightly different than its flooded counterpart. It uses a separator made of fiberglass between the positive and negative plates, which absorbs all the electrolyte solution. This design allows the battery to store the electrolyte in a dry state rather than a liquid form. Therefore, if the battery case is ever damaged or tipped on its side, the electrolyte will not spill. In addition, AGMs do not require venting like traditional flooded batteries, so they are less likely to have corrosion build-up on the terminals.
AGM batteries last approximately three to six years and have a slow discharge rate, so they can last up to two months without the vehicle being driven. They are resistant to vibration, charge up to five times faster than flooded lead acid batteries, and provide the ideal solution for the high-power demands of Start-Stop vehicles. In addition, AGMs stand up against extreme temperatures, making them an excellent choice for regions with high heat or freezing conditions.
Pros
• 3-6 year lifespan
• Leakproof
• Designed for harsh climates
• Vibration resistant
• Charges 5 times faster
• Low self-discharge rate
• Maintenance free
Cons
• Pricey: AGMs cost 25% - 50% more than traditional flooded lead acid batteries
Choosing between a traditional flooded lead acid battery or an AGM comes down to price and what your vehicle requires. AGM batteries typically offer greater safety benefits and better performance. Plus, they are required for vehicles with high energy demands. For most cars and trucks, traditional flooded lead acid batteries can perform the same job at a considerably reduced cost but won’t last as long. If you are comfortable making the up-front investment, an AGM is an excellent choice for the long term.
AAA provides Members with the highest quality traditional flooded lead acid and AGM car batteries, delivered and installed wherever you are. Call 1-800-AAA-HELP to schedule a visit from a trained Battery Service Technician for a free battery inspection.
