AGM Vs. Standard Battery: Which is Better?

As of 2022, there are 1.4 billion vehicles globally – 606 million in Africa, Asia, and the Middle East alone. And each one of them has a battery. Early cars didn’t have electrical systems and didn’t need batteries. But once the electric starter became common, cars needed re-chargeable batteries to turn over the starter.

Enter the Hudson Car Company. In 1918, Hudson began incorporating batteries into its vehicles. Since then, the flooded battery has been the dominant car battery. But times, and technology, have changed. Today, car owners have a choice in batteries: AGM vs standard battery. Let’s take a look at the pros and cons of each.

Overview: AGM vs Standard Battery

An AGM – which stands for Absorbed Glass Mat – battery and a standard lead-acid, flooded battery share several similarities. Both batteries use the same basic chemistry. Submerging lead plates into an electrolyte solution – water and sulfuric acid – produces free electrons that can be captured and used.

That same chemical reaction also produces hydrogen and oxygen. So far, so good. But when the batteries are being charged, they produce hydrogen sulfide – a dangerous gas.

Two major differences between AGM and flooded batteries are safety issues. How is the electrolyte – battery acid – contained? And how are the gasses the battery produces controlled?

Other differences are life span, starting power, maintenance, and shock resistance. And in both these and safety, AGM batteries come out on top.

Let’s take a deeper dive into the comparisons between AGM and flooded automotive batteries.

Standard Flooded Battery Design

Flooded batteries literally have a reservoir containing electrolyte – sulfuric acid. And battery acid is caustic. It burns skin, ruins clothes, and can cause blindness. And since the electrolyte needs topping off with distilled water periodically, flooded batteries have caps over the cells.

Needless to say, the caps can leak. For that reason, flooded batteries have to be installed – and kept – upright.

Because lead-acid batteries vent directly to the atmosphere, they emit explosive gasses when charging. Therefore, installation only in well-ventilated areas is essential.

If left unused, lead-acid batteries self-discharge at six to seven percent of capacity per month. Finally, because of their design, flooded batteries don’t tolerate vibration or impact as well as other batteries.

AGM Battery Design

AGM batteries use porous microfibre glass mats (the absorbed glass mat) to separate the battery’s negative and positive plates.

AGM batteries don’t have a reservoir of battery acid. Instead, the mats are saturated with enough electrolytes to stimulate the chemical process and activate the battery. The mats’ fibers are also embedded into the negative and positive plates. That gives added structural strength, making AGM batteries far less resistant to vibration and impact damage.

When your AGM battery is charging, and oxygen is produced, pressure release valves recombine the oxygen with the hydrogen internally. And that replenishes the electrolyte, making AGMs maintenance-free.

AGMs also self-discharge at much lower rates – roughly three percent a month.

Why AGM Batteries are a Better Choice

The design differences between AGM and standard flooded batteries are at the heart of why AGMs are a better choice. So let’s run through all of the pros and cons of AGM batteries. Then, you’ll see why replacing your standard battery with an AGM makes a lot of sense.

Zero Maintenance

Because AGMs are sealed and never require the electrolyte to be topped off, you can install an AGM and never worry about it. That also means more flexibility in where AGMs can be mounted. Combine zero maintenance with no fumes, and AGMs can be installed in less ventilated areas.

AGMs are Safer

AGMs are far safer than flooded batteries because they are sealed and don’t emit dangerous fumes. Remember the caustic battery acid and the explosive fumes lead-acid batteries produce? Switching to AGM batteries eliminates those dangers.

Far Less Risk of Spillage

No, you can’t install AGMs upside down. But you also don’t have to keep AGMs perfectly upright either. Because AGMs are sealed, there’s no worrying about battery acid spilling out every time you move or tip one.

Higher Power and Lower Resistance

AGMs’ lower internal resistance – under three percent – means the battery produces more power. Compare that to 10 –  15% internal resistance in a standard battery.

The lower resistance also means not as much heat is produced. And lower resistance has another benefit. It makes AGMs perform better under heavy loads than flooded batteries.

Less Sensitive to Vibration and Impact

The nature of AGM construction means that the sensitive lead plates are far better protected. As a result, vibration and impacts that would damage a standard battery are far less likely to damage an AGM. That adds up to a broader range of applications, including construction and off-road vehicles, motorcycles, and race cars.

Faster Charging

Remember AGMs’ lower internal resistance? Apart from the other benefits, lower resistance means charging AGMs is almost five times as fast as standard batteries.

Longer Life Span

Under similar conditions, an AGM battery will have nearly twice the life span of a flooded battery. A well-maintained standard battery should last between one and two years. An AGM? three years and more.

AGM Batteries: the Cons

There are two. The first is that AGMs are more sensitive to overcharging. And that means using a regulated – smart – charger. The second is that AGMs cost more on paper.

In reality, AGMs’ longer life span – plus all the other benefits – make them the cost-effective choice when it’s time to replace your car’s battery.

Bottom Line: AGMs are the Right Choice

Now that you know the differences between an AGM vs a standard battery, the choice is clear. With an AGM, you’ll be getting a much longer battery life span and a maintenance-free battery. In addition, the construction is more rugged, and AGMs produce more power. And they are safer, too—no dangerous fumes; no caustic acid to spill.

Make the right choice. Contact RB Battery to determine which AGM battery is best for your application. Their headquarters staff – located in Bangkok, Thailand – will be happy to answer all of your questions.