Vehicle Battery Types Explained

Car batteries are one of the great “unknowns” for most people. Their batter is just there under the bonnet, does what it needs to, and never gets any thought until it fails. With more and more people adding secondary and auxiliary batteries to their 4WD’s, there can be a lot of confusion about what type of battery to use for which application.

To start with, there’s two main types of battery, although some types of car battery may work for both. These are Cranking Batteries and Auxiliary Batteries.

Cranking Batteries

Cranking batteries, or starter batteries, are the ones that start your car. Most cars have one, but some have multiple batteries for extra voltage or as backups.

Cranking batteries are almost always lead-acid, and are heavy!

Newer cars with start-stop features normally run an EFB, or Enhanced Flooded Battery, which is specifically designed for that purpose. These are suited to situations where there’s constant loads put on and handle the start-stop better then a standard lead-acid battery.

Auxiliary Batteries

Auxiliary batteries are the batteries that you use to run all of your extra electrical equipment, like fridges, work lights and camp lights. These (hopefully) are isolated from your vehicles electrical system by a battery isolator or a DC-DC charger so that using your electrical gear doesn’t run your cranking battery flat.

Auxiliary batteries can be pretty much any type of battery, and the type that you use will depend on where it’s mounted and how it’s used.

Auxiliary vehicle batteries can be any of these types:

1. Lead Acid batteries
2. AGM (Absorbed Glass Mat) Batteries
3. Gel Batteries
4. Lithium Batteries

Lead Acid Batteries

Lead acid batteries are the most common, and normally cheapest, battery type that’s available. These are made for high-load applications and don’t like being discharged too much. They will run fridges and lights, but they won’t perform as well as other types because they are basically old technology.

AGM (Absorbed Glass Mat) Batteries

AGM batteries are one of the more popular deep-cycle batteries available as they normally offer greater output then a standard lead acid battery. They are made with the electrolyte suspended in close proximity to the active material of the batteries plates, allowing for enhanced performance.

Gel Batteries

Gel batteries are similar to AGM batteries but the electrolytes have an additive that makes it stiffer and more, well, gell-like. These are great for anything in hot weather, but are more sensitive to over-charging they AGM And lead acid batteries, so it’s recommended to use a proper smart charger with these to ensure that you get the most life possible out of them.

Lithium Batteries

Lithium batteries are the new kid on the block, and offer some huge advantages over traditional battery types. The biggest advantages are that lithium batteries can often provide 2 times the usable power of a traditional battery, and they are somewhere around ⅕ of the weight of a normal battery.

The downsides to lithium batteries are the price, which at this time is around 3-4 times the price of a standard battery, and the fact that they don’t like heat, so should not be mounted under the bonnet in most vehicles.

Auxiliary Battery Location Options

The biggest consideration when choosing a battery is where it will be mounted. The most common mounting locations are in the engine bay, under the tray (for utes and trucks) or in the cabin of the vehicle.

If you want to run a battery in the cabin of your vehicle, check with your local battery store for advice because it’s not only a bad idea to run a non-sealed battery in an enclosed space (they release fumes that can be intoxicating or fatal) but it might also be illegal, so this is definitely a time to ask the experts!