How Do Start-Stop AGM Batteries Work? Beginner Breakdown

Did you know that a start-stop system can improve the fuel consumption of your car engine by up to 15%? As fuel prices continue to rise, using this technology can mean a significant saving on how much you spend on your monthly fuel bill.

An integral part of the start-stop technology is the use of AGM batteries. These special batteries are designed to withstand the demands of starting your engine multiple times every time you drive your car.

Are you curious as to how these batteries work or how they are different from other types of batteries? You may be wondering what is an AGM car battery?

In this article, we explore everything you need to know about AGM batteries in a simple way that is easy to understand.

How Does a Start-Stop System Work?

As we move towards reducing our global CO2 emissions many new cars have started to incorporate start-stop technology. This system is designed to automatically turn your car engine off whenever you take your foot off the accelerator.

In most cars there is a 1.5 second delay between the moment you stop pressing the accelerator and when the engine cuts out. This prevents your engine from stopping for brief pauses like stopping at a stop street.

As soon as you put pressure on the accelerator again the car will automatically start again. Turning your engine off every time your car is stationary is a great way to reduce your fuel consumption and contribute to protecting the environment.

This constant restarting of your engine puts a lot of strain on your battery. Each time you start your battery needs to supply a large amount of current to turn the engine over. AGM batteries are considerably better at providing this power than any other type of battery.

What Is Different About an AGM Battery?

AGM stands for absorbent glass mat and these mats are the main difference between this type of battery and other lead-acid batteries. The electrolyte that holds the charge is stored in these fibreglass mats, rather than an acidic liquid solution.

This means that AGM batteries are much safer to use as there is no chance of acid spilling out of the battery in the event of an accident that damages the casing. It also means there is no need to ever top up these batteries or do any other maintenance.

AGM batteries are suitable for hybrid electric vehicles that use the energy created by braking to charge the car battery. This technology is called regenerative braking and uses the electric motor to divert power to your battery every time you stop your car.

Why You Need an AGM Battery for Start-Stop Systems

Conventional lead-acid batteries charge much slower than AGM batteries. This makes them unsuitable for start-stop applications as they do not store enough charge over short distances. In contrast, AGM batteries can charge up to five times faster and can reliably deliver the high power output needed to repeatedly start your engine.

This is due to AGM batteries having a much lower internal resistance than other types of battery. Internal resistance is the ability of the battery to consistently deliver a high current without the voltage of the battery dropping.

Another reason why AGM batteries are used with automatic start-stop cars is the depth of discharge (DoD). This refers to how much of the battery charge can be used before damaging the battery.

Regular batteries have a depth of discharge of around 15%. In comparison, AGM batteries can discharge up to 50% without harming the battery.

Advantages of Using an AGM Battery

One of the main benefits of using AGM batteries is that they have a much longer lifespan than regular lead-acid batteries. Even if you don’t use your AGM battery frequently they will still last longer and hold their charge better than other lead-acid battery types. This is due to the minimal self-discharge rate that they have.

The normal service life of an AGM battery is between 3 to 5 years in tropical weather and can be much longer in temperate areas. This is due to the ambient temperature of where the battery is stored. The hotter the average temperature is the shorter the useful service life will be.

Another advantage of AGM batteries is how durable they are. Due to the lack of liquid, they can withstand shocks and vibration without any problems. The fibreglass mats that make up an AGM battery are much stronger than regular battery components.

AGM batteries can also withstand large fluctuations in temperature without any damage. They function far better than regular batteries in cold temperatures.

Are There Any Disadvantages to AGM Batteries?

With so many great benefits to AGM batteries, you may be wondering if there are any drawbacks? The biggest disadvantage over regular lead-acid batteries is the up-front cost.

Although this is only to be expected when you consider that the lifespan is significantly longer. AGM batteries can easily last three times longer than flooded batteries and so it makes sense that they cost more.

The only other potential issue with AGM batteries is that they can be damaged by overcharging. This will never be a problem in your car as the charge controller will carefully regulate the battery charge.

Do You Need an AGM Battery? Contact RB Battery

The best choice for any automatic start-stop car is to use an AGM battery. These batteries can consistently deliver the power that your engine needs to repeatedly startup.

At RB Battery, we have 25 years of experience in manufacturing and supplying the best value AGM car batteries. With our extensive range of different types of batteries, you are sure to find the perfect battery to suit your needs.

Download our catalogue for a full technical description of all our different batteries.

When you are ready to place an order contact us and our sales team will help you through the process.