By FordMuscle staff.

Battery Basics
The lead-acid automotive battery hasn't changed much since Gaston Plante invented it in the late 18th century. A lead-acid battery creates electrical energy through a chemical reaction. Inside the battery are cells consisting of a lead plate and a lead dioxide plate both submerged in a sulfuric acid and water solution. The acid reacts with the lead plate (anode) to form lead sulfate and release two electrons. The electrons react with the lead dioxide plate (cathode) to form water and more lead sulfate. Each cell produces a characteristic 2.1 volts, and automotive batteries typically have six cells to produce 12.6 volts at full charge. One of the major reasons that automotive battery design hasn't changed much over the years is that this sort of electrochemical battery is fully rechargeable. When excess voltage is applied to the cathode (the function of the vehicles alternator) the reaction reverses and the battery recharges. This can be done over and over again, making automotive batteries a very long lasting and reliable power source.

The original battery design is considered a "flooded" design because the lead plates sit in liquid sulfuric acid and water. This liquid electrolyte solution adds volume and weight and is subject to boiling, releasing potentially dangerous sulfur acid vapor. A more recent design is the sealed lead-acid (SLA) battery (also termed valve regulated lead-acid VRLA.) These batteries immobilize the electrolyte either in a gel form, or by absorbing it in glass fiber plates that separate the cells of the battery.

Sealed Lead Acid Batteries
The advantages of an SLA battery present itself in the form of a smaller overall size and better safety since there is no liquid to spill or boil off. In fact, the battery terminals will never corrode either since there is none of the white sulfuric acid precipitate buildup outside the battery. The 12V Dyna-Batt, sold by Performance Distributors is a great example of how an automotive enthusiast can benefit from SLA batteries. The major gains come in weight savings. The Dyna-Batt weighs under 14 lb., compared to 30-45 lb. for conventional flooded batteries. The size also offers space savings, and can often be the solution in a cramped engine compartment when installing a larger engine or tubing for super and turbo chargers. Along with size, the ability to mount the battery in any position or angle also increases location flexibility.

On early Ford's the factory battery location was usually at the right front corner of the engine bay. This arguably counterbalanced some of the drivers weight. However on late-model Mustangs and other Fords the battery is on the same side as the driver making for some very poor weight distribution.	Just replacing the stock battery with a sealed lead-acid (SLA) type like the Dyna-Batt will shed weight off the front. Performance Distributors offers a nice bracket which can be used in placed of the stock battery tray. This battery is about the smallest SLA you'd want to run to power a V8 street car as it has a minimal 280 cold cranking amps.
Here we see how the Dyna-Batt fits into the stock early Mustang location on the passenger side fender. The stock tray has been removed and this has freed up sufficient space for the Vortech supercharger - not to mention offsetting the additional weight of the blower headunit.	Unlike conventional flooded lead-acid batteries, SLA batteries can be mounted in any position. This offers up a variety of other mounting positions and locations as seen here. The lifespan of SLA batteries are however affected by heat. This location will stay cool due to the air flow past the radiator support, but we'd recommend placing it in the trunk or using a head shield covering.

To play fair we should compare cold cranking amps (CCA) and reserve capacity (RC), as this is determined by the plate size which correlates to the size, and weight, of the battery. The battery council defines the CCA rating is the number of amps a new, fully charged battery can deliver at 0° Fahrenheit for 30 seconds, while maintaining a voltage of at least 7.2 volts, for a 12 volt battery. The higher the CCA rating, the greater the starting power of the battery. Reserve Capacity defines the battery's ability to power a vehicle without an alternator. The rating is the number of minutes a battery at 80 degrees F can be discharged at a load of 25 amps and maintain a voltage of 10.5 volts for a 12 volt battery. The higher the reserve rating, the longer your vehicle can operate should your alternator or fan belt fail. According to Performance Distributors, the Dyna-Batt isn't rated for CCA. The smallest battery we could find off the shelf at WalMart (pictured in the side bar) measured 8"H x 7"W x 5"D and produced 740 cold cranking amps. We've run both batteries in our Mustang and they both perform equally in terms of starting. Are we comparing apples to oranges? Some say comparing cold cranking amps of SLA and flooded batteries is akin to comparing Mac and PC processor speeds. While the rated numbers may be the same, the efficiencies and better design of the Mac, or in this case an SLA battery, results in much better performance than the conventional design.

Clearly if the SLA batteries were without any downsides you'd see their widespread use in production vehicles. After all, with today's fuel economy concerns an auto maker would kill for shaving 25-30 lb. from their cars. There are tradeoffs with SLA batteries, and they come in the form of temperature tolerance. SLA battery performance and life span deteriorates dramatically with heat. An SLA battery when maintained around 75 deg F. can last 8-10 years so long as it receives frequent charging. However at conditions over 100 degrees the battery life will degrade to under 2 years. Since underhood temps are routinely very high in a modified vehicle we recommend installing the SLA battery in your trunk. We've detailed how to achieve this on the next page.