The Top 3 Types of Car Battery and What You Need to Know?
Every car has a battery that helps them start the engine and powers the electric system. There are many types of car batteries, and if you have ever wondered about the kind that is in your car, this article covers the top car battery types; lead-acid, AGM, and EFB. However, we will start with what the 3 types of car batteries have in common.
What do lead-acid, AGM, and EFB batteries have in common?
Regardless of the type of car battery, you can expect high performance. Compared to about a decade ago, these batteries have vastly improved. They do not require as much maintenance and are more reliable even in varied operating conditions.
With a modern car battery, water loss has been reduced to the level that you no longer need to top up during the entire battery lifetime.
Lead-acid is the most common car battery type and was invented by French physicist Gaston Planté. Thanks to decades of development, they have evolved to be well-established.
A lead-acid battery has a negative electrode made from porous lead, hence the name. The positive electrode is made from lead oxide. Both electrodes are dipped into an electrolyte, a liquid mixture of sulphuric acid and water.
To prevent the two electrodes from coming into contact, there is an electrically insulating membrane between them. A chemical reaction occurs when you charge, which reverses during discharge.
During discharge, the lead and lead dioxide react with the sulphuric acid, forming lead sulfate in a finely divided amorphous state. The components return to lead, lead oxide, and sulphuric acid when you charge the battery.
The two electrodes contain the same material when fully discharged, but a lead-acid battery is prevented from getting to that point, known as the cutoff voltage.
Lead-acid batteries require maintenance because if left at a low battery state for an extended period, the capacity may be permanently reduced due to large lead sulfate crystals build-up. These crystals are difficult to convert back to lead.
The performance of lead-acid batteries is affected by the surrounding temperature. For example, below 20 degrees Celsius, you may lose about one percent capacity for every degree loss of temperature. On the other hand, high temperatures accelerate ageing, self-discharge, and electrolyte usage.
AGM stands for Absorbent Glass Mat. This type of car battery is an advanced form of the popular lead-acid. As a result of the improvements, it provides superior performance, making it useful for the increased electrical demands of modern vehicles, including the start-stop features.
For cars with many secondary electronic features, including powerful speakers, heated seats, GPS, etc., AGM batteries offer the deep-cycle capabilities needed to power them.
AGM batteries are made by introducing an absorbent glass. The glass separates the positive and negative plates, preventing the acid from flowing freely. The plates are held tightly in each cell, which prevents them from shedding materials due to cycling. This prolongs the car battery lifespan more, and it can last more than twice standard flooded batteries.
The compression also reduces the internal resistance, which maximizes the output. AGM batteries incorporate a relief venting mechanism to allow gases produced during charging to escape. The valve remains open at low pressures but will automatically lock to prevent air from entering the battery.
AGM batteries are less susceptible to vibrations, have greater mounting flexibility, and require less maintenance. They can also function under harsher operating conditions or climates. However, AGM batteries are more expensive.
EFB stands for Enhanced Flooded Batteries. In this sense, ‘flooded’ means wet or containing a combination of acid and water. To put this in context, a dry cell battery like that in your smartphone does not use battery acid. Instead, it contains a type of alkali in powder or gel forms.
When a battery is termed EFB, it is a standard lead-acid battery but with the internal structure improved upon. The improvements include lining each vertical lead plate with a special material known as polyfleece.
Polyfleece helps to slow down the effects of ageing on the battery. In a standard lead-acid battery, electricity is produced when the battery acid interacts with the lead plates, leading to a chemical reaction. However, the lead plates steadily degrade with more use and become ‘sulfated’ or covered with crusts. The battery then loses efficiency.
A coating of poly fleece on the lead plates prolongs the battery’s useful life. By keeping newly converted electrons closer to the lead plates, the coating ensures a more reliable electricity output from the battery.
EFB batteries are suitable for situations where the car engine shuts off to conserve fuel, and all the systems in the car, including the AC, stereo, navigation, etc., depends on the battery. Many modern vehicles use a start-stop technology to achieve this.
EFB batteries can provide approximately 85,000 engine starts, compared to about 30,000 from standard flooded batteries.
The lead plates in EFB are thicker. This modification allows deeper discharges than lead-acid batteries. They are fit for use in more demanding applications like motor homes, boats, etc.
If your car uses an EFB battery and requires a car battery replacement, you should install an EFB battery to maintain your car’s performance.
Electric car batteries serve an essential purpose in automobiles. However, since the invention of the lead-acid battery, improvements have brought other car battery types, including the AGM and EFB batteries, which can perform under more demanding applications.