Automotive Battery Options

For all this talk of paying attention to battery selection, there are, for practical purposes, three areas of importance that we need to look at. There are the two different types of battery construction, two design purposes, and then countless characteristics including quality of material and workmanship. Below we will unpack each one of these important elements to help you quickly and simply identify the battery that will suit your needs.

Flooded Batteries

The most commonly used and the most cost-effective battery construction type is the flooded lead acid battery. As the name suggests it is a battery made up of lead plates, flooded with an acidic formula. This formula is made up of battery acid and distilled water. The reason for the distilled water as opposed to tap water is that ions and other difficult to see particles regularly found in tap water is known to seriously reduce the lifespan of a battery’s properties.

It is worth noting that this water and acid mix is bad for your health. Especially when hot, it's bad for your clothes (sometimes taking days to wreak its havoc, often inside a laundry basket with other clothes), and it can damage automotive paint.

Sealed AGM

This title is a little less self-descriptive. The battery is, as implied, sealed. However, AGM stands for Absorbed Glass Mat. Instead of having freely flowing battery acid, the battery acid is soaked into a fiberglass matt.

These batteries are more expensive because manufacturing them is much more intentional. The advantages, however, can be well worth the price for many (but not all) applications.

For one, the absence of free water leads to the ability to completely seal the battery, preventing them from drying out. This makes them truly maintenance free. This is also what makes them more attractive to aquatic environments, or wherever there are environmental concerns. There is also much less internal resistance which means you can get more amperage out of the same lead plates, faster.

Due to the fact that there is faster, cleaner power output, AGM batteries are typically only used as a starting battery for on-road vehicles.

Design Purpose

Starting

This may seem obvious, and it is. All batteries are used for starting. Otherwise, all a vehicle would need is an external crank and a generator. The goal of a starting battery is to provide a starter motor with a short but high output of energy. We measure this in amperes. The battery is, of course, used after the start to supply a steady, dependable voltage to vehicle components like injectors, ECM's, lights and, of course, the alternator.

Deep-Cycle

This is a term that seems to be misunderstood, or forgotten, by many. A deep-cycle battery is designed to deal with more of a discharge than a starting battery. What this means is that it is more damage resistant to low voltage than a starting battery. The reasons that someone may care about this is that if a vehicle is not driven on a regular basis, or when accessories are used for a significant amount of time between when the engine is running, then the battery needs to be resistant to these demands. Where a starting battery will eventually "burn out" a deep-cycle battery is able to keep coming back for more. To a certain extent, of course. A deep-cycle battery is not limitless in its ability to take abuse. A tractor with a sleeper probably needs deep-cycle batteries.

Other Characteristics

On the tag

Typically, on a battery label we will find a lot of acronyms. The usual ones and the ones that matter are VLTS, CA, CCA, and RC. While VLTs must be 12, the others usually want to be as high as possible. This depends, however, on the application. Your owner's manual should tell you the recommended amperage output of your batteries. That being said, you rarely will have too much.

CA

Cranking amps. Often ignored for the sake of CCA, but very important. Cranking amps is the optimal amperage you can expect out of this battery, when healthy, in average climates and conditions. Best case scenario. Many people would read that as "it's only true on a test bench". I struggle to say they are wrong.

CCA

Cold cranking amps. The standard by which we hold our batteries to. Even when we don't live where there is any real cold. The CCA is to say how many amps can be delivered by the battery at 0 deg. f or -17 deg. c for 30 seconds. In other words, on the most miserable of days, a healthy battery should be able to supply you with this many amperes. This is, of course, much more valuable if you live in a cold climate. But always good.

Approximate loss of capacity by temperature

RC

Reserve capacity. The forgotten one, yet very important. This is actually not an expression of amperes or volts but of minutes. As in, how many minutes the battery can stay above the minimum of 1.75 volts needed to run a vehicle. Many people tend to ignore this number but it can be extremely practical when the accessories strap breaks or an alternator fails far from a shop. If your charging system were to fail, and your RC is 60, you should have 60 minutes of power to get to a better or at least safer place.

Other General Notes

After what has been discussed comes the many nuances of any given battery. Many of which are hard to see. Some of these characteristics may mean a tougher build, for heavy vibrations. Extreme temperatures such as northern (very cold) or southern (very hot) climates.

Unfortunately, many characteristics can be broken down to cost-cutting measures for which one rarely saves any money at all in the long-term. Without a doubt, the best way to discern all the particular characteristics of a given battery is to find a representative of a given brand who is well trained and has experience in helping you find the best battery for your needs. Not to despair, the most expensive battery is not always the best choice, nor should you automatically be convinced of this. A 15-liter engine spending its day in an icy field needs much more amperage, ruggedness, and durability than a 13-liter highway truck that makes 2 quick stops per day on two shifts and is otherwise always running.

There is also a noticeable difference in warranties given for different batteries. 12 months seems to be the minimum worthy of being trusted. This is not always enough. If you plan on selling the vehicle receiving the new batteries it may not matter to you at all, but otherwise, a warranty can be a good indicator of the quality of the battery. Don't trust the stamp on the battery or what is written in the brochure, ask about the process to claim a legitimate warranty and examples of someone else who has successfully claimed one. On the other hand, too many off the cuff examples of warranties may mean a high percentage of failure.

Drive safe,

Kevin Gauthier