Case Studies

Car Batteries – Facts About Lead Acid Or AGM Types

Why AGM Batteries?
Absorbent Glass Mat batteries (AGM) have been a market favorite for the past decade for reasons of capacity and durability. These batteries are becoming much more common in European and imported autos like Audi, BMW, Mercedes, Mini Cooper, Volvo.

How They Work
In principle, the AGM batteries work like any other lead battery. However, the AGM batteries, compared to flooded batteries, have several significant improvements that make them more efficient. Additionally, just like other types of batteries in the market, they have their advantages and disadvantages.

Choose The Right Type
The right battery for your car will give good service from 3 to 5 years, maybe longer if well cared for. The #1 reason for battery failure after battery replacement, is the use of the incorrect battery type. Most late model cars are very dependent on a stable and properly operating electrical system, generic battery replacements, jump starting, or even weak batteries can wreak all kinds of havoc with your auto. If you car came with a AGM battery, it must be replaced with the same for reliability, and durability. Switching from the AGM battery types trying to save money will only cost more in the end, with damaged electronics, short battery life, dead batteries, no starts, and towing. Don’t take the chance.

Be Sure To Program If Needed
For some cars, like BMW and Mini Cooper, the other reason for battery failure after battery replacement, other than the use of the incorrect battery type, is the failure to properly program the car, these cars require the engine computer, known as a DME (Digital Motor Electronics) must be programed to know a new battery has been installed.

Otherwise the battery can under or overcharge, and cause premature battery failure. Older batteries become sulfated with time and require a higher charging rate. So unless the DME is notified a new battery is installed, it will often overcharge, and damage the new battery in short order.

Advantages of the AGM Battery
1. They are spill proof – Unlike the traditional lead-acid batteries that freely flood their electrodes, AGM batteries have glass mats that prevent this. Additionally, it is the function of these glass mats to avoid spillage. Rather than absorbing the electrolyte, the glass mats work by holding the electrolyte in place, preventing it from spilling over, even when the battery is placed in odd positions.

2. They have a high-power output – Because of the way that they are designed, the AGM batteries have minimal internal resistance. This, therefore, enables them to provide sufficient bursts of power when necessary, such as when one needs to start a battery. Due to this feature, these batteries respond better to loading than any other battery on the market.

3. They have a short charging time – AGM batteries, compared to flooded batteries, charge quickly. When compared to flooded batteries of a similar capacity, the charging rate can reach five times faster with the same power source.

4. They have a longer lifespan – AGM batteries have a longer lifespan than traditional flooded batteries. Moreover, not only do they serve for a more extended period when they perform the same tasks, but they also last longer when they are not in active use. This is because self-discharging is minimized in these batteries, unlike other types of batteries, which is a huge problem. This ensures that one does not have to keep charging them after an extended period of inactivity.

5. They are durable – These AGM batteries were originally designed to serve the aircraft industry. This means that they have a sturdy design, one that can handle conditions of intense vibrations, just like those in military and commercial aircraft. Because of this property, they are a favorite for high-end motorcycle riders and race car drivers. The sandwich construction method adopted in their design ensures that their internal components do not fall apart. Moreover, they are invulnerable to the subsequent wear and tear that may result from frequent and continuous vibrations. Furthermore, they can withstand extreme temperature variations.

6. They are unlikely to build up sulfation – Sulfation is the property of lead-acid batteries, where there is a gradual accumulation of lead sulfate crystals in the cells. In most cases, it is the cause of failure in lead-acid batteries. Sulfation mostly occurs when the battery is not fully charged, and thus the crystals continuously build up on the plates. When this process goes out of hand, it prevents the efficient conversion of chemical to electrical energy. Therefore, for other types of lead-acid batteries, it is essential to charge them every six months to prevent sulfation. However, in AGM batteries, sulfation is significantly reduced. Therefore, they can be stored for extended periods without needing a recharge.

Have Questions?
For more information on AGM batteries and other types of batteries, please call one of our Service Advisors, they can offer valuable information on various types of batteries and which battery works for you.

At Atlantic Motorcar, we’re all about providing our customers not only Great Service but also Value. We understand that “An ounce of prevention is worth a pound of cure.” (my mom would be proud I remembered that.), in other words, preventing, or catching problems like these brake lines early, can save you more than just money.

Questions, or if we can be of help in any way with service on your Audi, BMW, Mercedes, Mini Cooper or other European (and now Japanese) import, please contact us. Our team of Service Specialists is here to help, for even the newest autos! (207) 882-9969.

Knowing, not just “doing”, that’s the Atlantic Motorcar Center way.

The Atlantic Motorcar Center Service Team


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