Wondering what type of car battery you have in your car? If it’s time for a replacement battery or if you’re thinking of upgrading to a different kind of battery, you’ll want to make sure you pick up the right model for your vehicle. Maybe you need to buy a charger for the battery you already own. Either way, check out this car battery guide that can help you figure out what is under your hood.
Where’s My Battery?
Identifying your battery means looking at it, but where is it? In the past this was an easy question to answer as most car batteries were mounted under the hood near the front of the engine bay. But space concerns of modern vehicles have lead to all kinds of interesting battery mounting locations. Under the hood is still common, but sometimes it can also be found in the trunk or under a car seat inside the cabin. More creative solutions may require removing a fender panel or even the front bumper. If you have a hybrid or fully electric vehicle you will likely have two batteries, one for propulsion and one for 12v systems. Vehicles with “start-stop” fuel saving systems may also have a smaller auxiliary battery tucked away to provide power while the engine is shut off. The simple answer is to consult your owner’s manual for the exact battery location so you can see it for yourself.
Car Battery Types
There are only a few different types of car batteries on the market and most will fall into the following categories:
Lead-Acid Wet Cell
Lead-acid batteries are the oldest car battery type and, as a result, the most common. These batteries have been the workhorse of the automotive industry for decades. The design is fairly simple with a case that contains a series of lead plates bathed in an acid solution to create electricity. The majority of these batteries are classified as a wet-cell design, and most are easily identifiable by the caps at the top. These caps allow them to be opened up and topped off with distilled water from time to time during the course of their lifespans. In some cases, the entire top of the battery can be removed. These types of car batteries are also almost always labeled as such (or as wet-cell units), which makes them easier to spot, but even sealed, maintenance-free batteries will slosh around a bit when shaking them if you can’t locate a label. They must be kept upright to prevent spilling the liquid acid inside.
Lead-Acid Gel Cell (or Dry Cell)
Increasingly, modern lead-acid batteries do not require any servicing, and some no longer use a flooded liquid acid setup to generate power. Known as dry-cell batteries, they contain an electrolyte in gel form and are completely sealed with no need to ventilate gases like a wet-cell battery. They might look similar to wet-cell units but are notable for their flat tops and complete lack of filling ports or caps. In addition to their labeling, an easy way to differentiate between these two types of lead-acid batteries is to shake them. A wet cell will continue to move around inside for a short time after you stop shaking, while a gel-filled battery will not.
Absorbed Glass Mat (AGM)
Like a gel cell, absorbed glass mat or AGM batteries are a lead-acid dry-cell car battery type that are completely sealed and do not require topping off or any other type of maintenance. Instead of water or a gel, AGM batteries use a fine network of glass fibers that create a mesh inside the battery. AGM batteries are especially popular with racing and off-road enthusiasts thanks to the spill-proof design and typically vibration-proof construction. As with the gel cell, shaking the battery won’t lead to any extra movement once you’ve stopped, but other than labeling it’s hard to tell an AGM apart from a gel cell. An exception is Optima brand AGM batteries which can be identified by their “six pack” battery case which contains the six spiral cells made of absorbed glass mat and lead sheets. When in doubt, look up the battery’s details online using its model number.
Most automotive lithium-ion batteries are found in the battery packs of fully electric vehicles and hybrid vehicles. These packs are usually found in the lower parts of the vehicle and can only be seen by removing covers or interior trim pieces. But they are also a trick lightweight alternative to traditional batteries when used at the race track or other specialty vehicles like exotic cars. They can also be found in ATVs, UTVs, motorcycles and other powersports applications. The attraction is lighter weight and higher capacity in a small physical package. These batteries pack a punch for their size.
Nickel–Metal Hydride (NiMH)
Nickel-metal hydride batteries are another type mostly found in fully electric and hybrid vehicle battery packs. These batteries were the workhorses of vehicles such as the Toyota Prius, Ford Escape Hybrid and the famous General Motors EV1. The chemical design works well for high-current applications, which is why they were widely adopted. But technology has moved on and other battery designs such as lithium-ion are taking over.
You may be asking why deep cycle is not listed here. Deep cycle batteries are designed for applications where the power draw is low, but over a long period of time. While they may look the same as your car battery, deep cycle batteries are more suited for golf carts and trolling motors.
Check out all of the car batteries available now on NAPA Online or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on understanding car battery types, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.
Photo courtesy of Wikimedia Commons.
Having been bitten by the car bug at a young age, I spent my formative years surrounded by Studebakers at car shows across Quebec and the northeastern United States. Over ten years of racing, restoring, and obsessing over automobiles lead me to balance science writing and automotive journalism full time. I currently contribute as an editor to several online and print automotive publications, and I also write and consult for the pharmaceutical and medical device industry.