Why Upgrade Your Electrical Output?
Newer 4x4s are equipped with batteries that meet their electrical needs, and those needs are much greater than those of their predecessors. Fifteen years ago, some manufacturers would have told you that most vehicles on the road in 2020 would be running 48V systems—due to the increased electrical demands of newer cars for hybrid systems, safety features, and increased electrical needs in-cab. But the great majority of newer vehicles are still using 12V- (closer to 14V-) based DC electrical systems with more powerful alternators and improved lead-acid batteries that have higher cranking amperages and longer reserve capacities. And these systems do not leave a lot of room for additional electrical draw, thanks to the increased electrical needs. Luckily for you, the aftermarket will find anywhere there is room for improvement!
Most factory automotive batteries are wet cell lead-acid batteries—and they are always sufficient for the power draw of your stock vehicle. If you’re adding more draw on your electrical system, you should be checking out a battery with a higher reserve capacity and amperage. While there is obvious reason for increased battery power if winches, lights, or large stereos are added, is there reason for upgrading to better battery power if your electrical system remains otherwise stock? In the off-road world, we’d say definitely yes. The great majority of off-roaders use AGM (absorbent glass mat) batteries that are sealed, can be mounted at any orientation, and are spill proof—much safer for an off-road vehicle. Beyond that, an AGM replacement battery will almost always have a longer reserve capacity that will allow you to listen to the radio longer at camp or run a portable freezer/fridge for much longer.
Perhaps the most famous AGM battery is the Optima RedTop that has roots dating back to the ’70s. Optima uses a Spiralcell technology that feature six spiral-wound rolls. Each roll is made of two pure lead plates separated by a micro fiberglass blend that holds the electrolytes in a uniform suspension and keeps the plates from touching. The Spiralcells are bound together in a virgin polypropylene housing with the familiar Optima Six Pack design. The history and experience that Optima brings has kept them as a leader in the AGM battery power market for many years and while there are other options, there are also a number of kits out there designed specifically for Optima battery housings, making them often the easiest choice to turn to when making a battery upgrade. Whatever your 4×4’s electrical needs—and they can vary greatly from vehicle to vehicle—there is really no downside to improving the power bank that supplies your vehicle’s electrical requirements.
Common Battery Measurements
Voltage (V): Volts are the unit measuring the difference in electrical potential between the positive and negative terminals of a battery.
Current (I): The rate of flow of charged carriers (usually electrons or electron-deficient atoms).
Amperage (A): Unit of electrical current, amps are defined as the amount of electrical charge that flows through a conductor in a given time.
Cranking Amps (CA): The current a battery can provide for 30 seconds at 32 degrees F without dropping below 7.2 V.
Cold Cranking Amps (CCA): The current a battery can provide for 30 seconds at 0 degrees F without dropping below 7.2 V. Modern-day industry requirements are based on CCA, but it is a more relevant measurement for people who live in sub-freezing climates.
Marine Cranking Amps (MCA): same as Cranking Amps. A measurement more common for batteries not used in icy conditions.
Hot Cranking Amps (HCA): The current a battery can provide for 30 seconds at 80 degrees F that a battery can provide without dropping below 7.2 V. This is not really a common way to measure automotive batteries anymore.
Reserve Capacity (RCM): The battery’s ability to deliver 25 amps at 80 degrees F while sustaining a minimum of 10.5 V, measured in minutes.
What is an AGM Battery?
The Optima RedTop is an AGM battery with lead plates turned into Spiralcells for a signature look that has distinguished Optima batteries for years. AGM batteries are non-spilling VRLA batteries that come in both starting and deep cycle versions and have their lead plates separated by media that hold the electrolytes close. These batteries are often mistakenly called “dry cells” or “gel cells”—both of which are incorrect. Dry cell batteries are not used in auto applications, and while gel cells are used in auto applications they are much less common than AGM replacements.
The Benefits of AGM Battery Power
Adding electrical accessories like winches, off-road lights, and big stereos can all suck a lot of power—winches and stereos especially. The momentary massive power draws that an amplified stereo or a winch requires can easily be noticed by the dimming of interior lights or headlights. This can be a clear indicator that your electrical system is underpowered. AGM batteries can handle larger power draws of all durations and usually have larger reserve capacities that can keep the lights on longer!
While the addition of electrical accessories can necessitate an improved battery power setup, so can modified integral electrical components. This Powermaster starter delivers much more torque than the stock one did, and requires a fair amount more power. And an AGM starting battery can deliver more power for starting an engine. There was an audible difference in cranking power with the addition of an AGM battery that supplied more current to this setup.
Adding a larger bank of power to supply your electrical accessories will definitely improve things, but if the constant draw of power has increased, it would greatly enhance your electrical system to add an aftermarket alternator like one from Powermaster. The difference of the parasitic draw on your engine’s accessory drive will be negligible but the benefit will be obvious.
A charger specially made for AGM batteries might be a good option for those of you who see more battery woes than others or have multiple vehicles. This Digital 1200 12V Performance Charger from Optima enhances the performance of AGM and flooded wet cell batteries, and can also better detect and bring back deeply discharged AGM batteries.
Dual Battery Setup
When the power needs increase in an off-road vehicle, most enthusiasts opt for a dual battery setup rather than moving to a single larger group size battery with a higher cranking amperage and longer reserve capacity. It is unlikely you could easily fit a single battery large enough to equal the reserve capacity offered by a dual battery setup, and a second battery can be remotely mounted (or both batteries can be remotely mounted if desired).
Another benefit of a dual battery power setup is that you can use relays or solenoids to separate your batteries. This is done so that you never drain your engine starting battery using other electrical accessories at camp when the engine is off. Not only that, but a dual battery system can allow you to jump your own vehicle should the starting battery become too discharged to crank the starter.
Bringing an AGM Battery Back from the Dead
Sometimes a battery that seems dead … isn’t. There is a chance that the voltage in the battery has dropped so low that your standard battery charger can’t detect it. A way to sort of fool a charging system is to double-up and charge two batteries at the same time, in parallel. By jumping another (charged) battery into the system, the charger will start charging and the very discharged battery can scavenge the charge. This does not always work but it is definitely worth a shot before you scrap a valuable AGM battery.
Common Battery Terms
Wet Cell Lead Acid: A wet cell battery is one that has a liquid electrolyte solution that creates energy by means of chemical reaction. A wet cell lead acid battery is also known as a flooded battery or a liquid lead acid battery. It has free liquid electrolytes that are free to move within the cells. There is access to the individual cells and distilled water can be added if the battery dries out (decreasing its ability to hold power).
Sealed Lead Acid (SLA): The internal structure of an SLA battery is basically the same as a flooded wet cell battery but has no access to the cell compartments. This includes AGM and gel cell batteries as well as other battery constructions.
Valve Regulated Lead Acid (VRLA): A valve regulated lead acid is a recombinant battery that prevents the movement of electrolytes within the housing. The oxygen and hydrogen recombination occurs within the cell. A VRLA battery is a more accurate and specific term for what most enthusiasts are talking about when they speak of sealed batteries. The two main types of VRLA batteries are AGM and gel cell.
Absorbent Glass Mat (AGM): An AGM battery is a sealed lead acid battery that uses lead plates separated by ultra-thin fiberglass mats saturated heavily with battery acid. This type of construction keeps the electrolytes close to the lead plates. The tight packing makes them very resistant to vibration and completely spill proof.
Gel Cell: A gel cell battery most commonly contains a silica-type gel. It is a sealed lead acid battery specifically designed for deep discharge cycles. These are not overly common in automotive applications. While a gel cell has been often mistakenly synonymous with the term “AGM” and “dry cell” this is incorrect. A gel cell is an SLA but not an AGM and an AGM is an SLA but not a gel cell. And neither are dry cells.
Dry Cell: A dry cell battery uses an electrolyte paste with a graphite rod or some other carbon cathode as a central rod. This is typically a portable battery like a AAA or 9V in your smoke alarm and not actually something used in automotive applications. A dry cell is neither an AGM nor a gel cell battery.
Group Size: The Battery Council International (BCI) group sizes are specified for length, width, and height of batteries. This group sizing is one that all automotive battery manufacturers adhere to. The most common aftermarket replacement battery group size for the off-road industry is a Group 34.
Date Code: A date code can be found on most all batteries, since batteries can lose their charge over time while stored.
Starting Lighting Ignition (SLI): SLI battery power is what most automotive batteries are. They are able to deliver a large amount of current for a short duration of time and are not designed for deep discharging.
Deep Cycle: A deep cycle battery is made to handle repetitive discharges and recharges multiple times, being discharged using almost its full capacity. These batteries generally have long reserve capacities and are generally made to be drained more deeply and slowly over a longer period of time.
Editor’s Note: A version of this article first appeared in the September/October 2020 print issue of Tread Magazine.