In years past, an automotive battery had one single job – to provide starting power when the key clicked forward. You’re about to find out that’s not nearly the case with modern vehicles, as the need to provide power not only during the starting cycle, but at other times as well. This means picking the correct battery for your application is no longer as simple as walking into the local parts store and picking one up off the shelf.

Extreme conditions only serve to exacerbate the need for a battery to be able to provide starting power. After looking through the options offered by Optima Batteries, we thought it prudent to get the information straight from the source.

Cranking Power Versus Key-Off Power

This cutaway of a REDTOP battery shows how each cell is organized within the battery’s case. Positive plates and negative plates are connected (but not to each other) and to the terminals atop the battery.

Starting a vehicle requires a quick burst of large power – that’s where the term CCA (Cold Cranking Amps) comes from. Batteries are specified to provide the proper amount of Cold Cranking Amps for the application, but it’s the need for power when the owner is not attempting to start the car that has driven advancements in battery technology over the last several years.

“The change in vehicle electrical needs has increased as they have become much more sophisticated from an electronic standpoint. Since the introduction of OBD-II and moving forward, each year another component is powered by electricity – power steering, electric water pumps, minivans with dual power sliding doors, power SUV tailgates, and side steps. Things like that can put a significant strain on the electrical reserve power in the battery,” says Optima’s Cameron Douglass.

“The alternator should be putting out enough amperage to keep the car running properly but there are times when electrical demands peak above the capability of the alternator. I know a soccer Mom or two that lets the kids play power hungry entertainment systems in the minivan when the motor isn’t running. Anytime the electrical demand exceeds the capability of the alternator is when a good battery is put to the test.”

As all of today’s vehicles are computer-controlled, the need to provide power when the car is turned off is now a large part of specifying the proper battery for an application. The computer keeps running when the car is turned off and this requires the battery to provide enough power when the car is turned off – what Douglass calls “key-off load”.

“What has increased over time dramatically is the key-off load and that’s pretty significant today. We have the privilege of working with the OE manufacturers to provide solutions to their needs in terms of key-off power. An older car typically had no load when the key was off and could stand for 60 days, and would still fire up, but that term has shortened significantly. There are many more things that a car has to do today besides just keep the radio stations in memory – it consumes more energy to keep the car alive. Communication with the key fob, or an alarm system, or whatever it might be, those things are all consuming some small amount of energy, and when you add them all up it can be a lot.”

When an enthusiast starts modifying a vehicle, whether it’s for performance or creature comforts, that opens up a whole new can of worms.

It's critically important to determine the proper battery design for your needs. A daily driven vehicle will be best served with a REDTOP battery, while a racecar or occasional cruiser might be better served with a YELLOWTOP. A deep-cycle YELLOWTOP battery is best where there is no alternator in play - but it must be maintained religiously to assure power is there when necessary.

SLI Batteries Versus Deep Cycle Batteries

The change in vehicle electrical needs has increased as they have become much more sophisticated from an electronic standpoint. – Cameron Douglass, Optima Batteries

SLI stands for Starting Lighting Ignition, and these batteries are designed to perform in high start output situations where only light surface cycling takes place. They are typically used for short bursts of power like starting the engine that has an alternator ready to top it off right away. They’re designed to rock on like a champ when you turn the key, then go back to their normal state and receive a recharge from the alternator.

Car batteries supply the extra power necessary when the electrical demand exceeds that which the alternator can provide. In addition, they also act as a voltage stabilizer in the electrical system to even out voltage spikes and keep them from damaging the sensitive electrical components in your vehicle. Optima’s SLI battery is the all-too-familiar REDTOP, which is designed to handle these conditions with ease as long as the electrical demands are within reason.

An assortment of Optima batteries – note the dark gray case on the REDTOP and BLUETOP  – this denotes their SLI batteries, while the YELLOWTOP uses a light gray case, which means it’s a deep-cycle battery.

A deep-cycle or dual-purpose battery on the other hand, is typically used in applications where the system load exceeds the alternator output by an unusually high margin, like when you’ve got a high performance audio system in your car running a couple of amplifiers.

For example, when you’re cruising around at near-idle, the alternator is not outputting maximum power. The deep-cycle battery can help to support the load with high current as the amplifiers demand it, then recharge quickly when the alternator output rises again when the vehicle is under power.

Each time the battery discharges, this is considered a cycle and can occur multiple times throughout the operation of the vehicle. Deep-cycle batteries are also very useful in RV, trailer and tow rig applications where the demand is much greater than the vehicle’s alternator can support. The YELLOWTOP and BLUETOP batteries are offered in deep-cycle units, but there are some conditions to this, as we’re about to find out.

Construction

In a traditional lead-acid battery, there are a number of cells that are separated within the case. Inside each cell there is both a positive (cathode) plate made of lead and a negative (anode) plate made of lead dioxide. There is a sulfuric acid electrolyte (38% sulfuric acid and 62% water) in which the plates are immersed.

Positive plates are connected to one another, as are the negative plates (but not each other). The plates immersed in the acid solution cause a chemical reaction that releases electrons – this creates electrical current. As the battery discharges, the acid reacts with the lead surfaces of the plates, changing the surface to lead sulfate.

The process is reversed during the charging process as the current causes the plate pack to shed the sulfate absorbed during the discharge cycle back into the acid solution, reforming the sulfate into lead dioxide and lead.

Left - Optima's SPIRALCELL technology keeps the positive and negatively-charged plates tightly wound to maximize their surface area and provide more power under all conditions. Right - In this cutaway you can see how the individual plates are tied together to meet up with the battery terminals.

All Optima batteries are constructed using their SPIRALCELL technology, which is vastly different from a traditional automotive battery. Rather than using the flat plate design described above, each cell in an Optima battery is spiral-wound with two 99.99% pure lead plates (one positive, one negatively charged) coated in lead oxide.

The two plates are separated in each cell by a micro-fiberglass blend that keeps the plates from touching (and shorting out) and also holds the electrolyte in suspension uniformly. The tightly-wound spiral construction allows for a much greater surface area, enhancing power production and greatly reducing vibration concerns as they are tightly-packed into the case.

Maintaining Your Battery

The Optima Digital 400 12-volt Performance Maintainer and Battery Charger is one of the options to keep your battery charged up so that it’s ready to go when you need it. Those of you who have a Sunday car that goes to the local cruise-in and then sits all winter are certainly not charging the battery back up every time you use the car. Having one of these in your arsenal is a good starting point.

It maximizes battery life and performance through the built-in battery health mode, and offers the occasional-use vehicle a new lease on life to ensure that it will start when you turn the key. Douglass says it’s even delivered with extra-long leads that can be permanently affixed to the battery, allowing you to use the spark-free connection technology to just plug it in when necessary. The company also offers their full-bore Digital 1200 Performance Charger.

Red, Yellow, or Blue?

Optima offers three different styles of battery in both SLI and Deep-Cycle designs. Optima’s product line in the various group sizes (physical dimensions) is available to cover approximately 65 percent of the automotive marketplace, in vehicle applications that Optima has found to most often require their products.

The REDTOP SLI battery is designed to provide high cranking power for vehicle starting, then relies on the alternator to run the stock accessories and rebuild the charge delivered at the turn of the key. A typical daily-driven vehicle with an alternator will be most at home with a REDTOP under the hood – unless it has a lot of electrical equipment onboard like electrical fans, monster fuel pumps, or the aforementioned high performance audio system.

“Optima has two different chemistries, even though we have three different battery types. We have the batteries that maximize starting power – the REDTOP or BLUETOP batteries with a dark gray case are the highest CCA batteries. The REDTOP line is all starting batteries, the BLUETOP line offers starting and deep-cycle options, and the YELLOWTOP and BLUETOP batteries denoted by their light gray case are all deep-cycle,” explained Douglass.

The YELLOWTOP is designed for heavy cycling capability. In the high-performance audio system setups, these are often used in a multiple-battery system to ensure that the vehicle has enough power to support the amplifier draw in addition to starting power. They’re also good on off-road applications where the vehicle might have multiple lights or a winch that will drain a typical SLI battery right down and render it useless.

“Our starting batteries have super-high CCA per pound. They aren’t designed for regular deep cycling. The YELLOWTOP has still very high cranking power, so for most starting applications it’s fantastic, but the benefit there is that it has very high cycle life.”

High-draw electrical fans and fuel pumps also present a high drain on the charging system. In a racing application, a YELLOWTOP will be a good choice to ensure that the power is there when required, especially if it’s a racing application where no alternator is present. This is especially important for drag racers that run electric water pumps, electric fans, and power hungry solenoids. Douglass states that it’s incredibly important to make sure you are topping off your battery between rounds.

The YELLOWTOP is also ideal for a vehicle that is parked for long periods of time – like with a show car that only moves in the summertime. In these situations, it’s extremely helpful to use a battery maintenance device, which you can read about in the sidebar.

Bobby Unser’s RV relies on Optima’s BLUETOP batteries exclusively. Note that these are light-grey case deep cycle units.

BLUETOP batteries are most at home in RV and marine applications. Why is this, you ask? Well, according to Douglass, marine and RV applications use a ring terminal for the power connections rather than a typical automotive lug design. Internally, the SLI version of the BLUETOP is identical to the REDTOP, but the different post and terminal design steers it toward the RV and marine user. The deep-cycle version of the BLUETOP is identical to the YELLOWTOP save for the terminal points.

In Conclusion

The automotive battery isn’t just for starting your car anymore and as you can see, there’s a lot that has to be taken into account when selecting a battery for your daily driver, weekend cruiser, or even your tow rig. Make sure to calculate your electrical system’s requirements and choose wisely.