The Battery Basics

The battery’s role in a motorcycle-powered racecar’s performance is often overlooked.  Few realize that even slight decreases in current can have a significant impact on an engine’s performance.  Picking the right battery for your application can easily contribute as much to the performance of your car as any other engine modification.   

Key to the performance of your race car
In most automotive applications the battery acts as the vehicle’s initial source of energy--used to start the engine.  Once started the alternator takes over to fill the engine’s electrical needs and to restore energy to the battery.  This is often not the case in a motorcycle-powered racecar.  In most motorcycle-powered racing applications the alternator has been removed since it represents significant rotating weight on the crankshaft.  As a result the battery becomes the sole provider of electricity whenever the engine is running.  As the

 
battery discharges and the voltage supplied to the engine drops, the spark used to fire the engine is weakened, robbing the engine of performance.  In many cases this drop in voltage is misdiagnosed as a carburetion or ignition problem. 

In most instances the presence of an alternator means that the battery is re-charged while the engine is running.

Since an alternator is not present in most motorcycle-powered racing applications, the battery is discharged the entire time the engine is running

What are your options?
Batteries are commonly classified along lines of purpose and composition.  There are three basic categories of batteries (according to purpose) including Starting, Deep Cycle and Hybrid. 

Starting Batteries
Starting batteries (also commonly referred to as SLI—starting, lighting and ignition batteries) are designed to provide large current draws for very short periods of time. They are most commonly found in passenger type, automotive applications.  Starting batteries are usually rated according to the amount of cold cranking amps (CCA) they provide.  Generally the act of starting a car only discharges the battery 2%-5%.  For this reason starting batteries can usually withstand several thousand cycles. (see sidebar—What is a Cycle)

What is a Cycle?
The life of a battery is commonly communicated in terms of cycles.  A “cycle” refers to one complete discharge and recharge cycle.  The deeper a battery is discharged, the shorter its life.  If a battery is discharged to 50% capacity every day, it will last approximately twice as long as a battery that is discharged to 80% each day.

Deep Cycle Batteries
Deep cycle batteries are most commonly found in applications that require a continuous current for a sustained period of time.  Deep cycle batteries are used for applications like electric cars and golf carts.  Deep cycle batteries can generally be discharged up to 80% of the batteries capacity.  Deep cycle batteries are capable

of withstanding several hundred cycles.  Conversely a starting battery that is deep cycled may only handle 30-150 cycles.

Composition
Batteries are also divided according to the composition.

Flooded
Flooded batteries are the most common.  They are the traditional battery that contains a combination of water and electrolyte (acid).  The biggest disadvantage of using a flooded battery in an auto racing application is that they can easily spill acid in the event of an accident.  They also tend to be less resilient, tending to succumb to the increased vibration of a race car.  Flooded batteries require the periodic addition of water.

Gel (Gelled Electrolyte)
These batteries are much the same of a flooded battery with one exception, Silica Gel has been added turning the acid into a solid mass that looks much like gooey Jell-O.  The biggest advantage of these batteries is that it is impossible to spill acid even if they are broken or split in an accident.  The biggest disadvantage of gel cell batteries is that they charge much slower than traditional batteries.  Additionally, overcharging a gel cell battery can cause voids in the gel that will never heal causing a loss in battery capacity.

Absorbed Glass Mat Batteries (AGM)
The newest battery composition is the Absorbed Glass Mat (AGM) battery.  AGM batteries are also commonly referred to as Dry Cell batteries.  The battery gets its name from the Boron-Silicate glass mat present between the battery plates.  Since all the electrolyte (acid) is contained in the glass mats, there is nothing to spill—even when broken.  Additionally, AGM batteries are also capable of taking much more abuse.  AGM batteries also have the addition of being maintenance free—no water to add.  The biggest draw back of an AGM battery is that they might cost more than 2 to 3 times that of a traditional flooded battery.  When it comes time to recharge, the AGM battery charges 2 to 3 times faster than the others. 

So given the options, what is the best battery to use in your motorcycle-powered application. Speed Partz, a company that specializes in motorcycle-powered racecars, offers the Odyssey, Deep Cycle, Dry Cell battery as their premium battery. “After much research, we determined that the Odyssey is clearly the best choice for use in modified midgets, mini-sprints, dwarf cars and TQs, explained Speed Partz’s, Larry Fasse. The Odyssey is classified as a hybrid, dry cell battery. “Since most applications (motorcycle-powered) are not 

 The Proof
During a recent evening of racing, multiple readings were taken with a voltmeter on the Odyssey and a standard Lead/acid battery.  The Odyssey did not experience a significant loss in output (voltage) as it discharged.  It remained well above 12 volts for the entire evening of racing.  Conversely, the standard battery did show a significant loss in output (voltage) throughout the evening, dropping below 12 volts and requiring additional charging throughout the evening.

using an alternator, the battery is required to produce a sustained current for the duration of the race.  Throw in the intense vibrations of racing and the potential for accidents that could spill the contents of a battery, and it is not hard to understand why we went the Odyssey”, Fasse continued.  The Odyssey has been described as both a world class sprinter and distance runner, capable of providing 2 to 3 times the cranking amps of standard starting batteries while also maintaining the ability to cycle more than 400 times at 100% discharge.

For more on the complete line of Performance Motorcycle Batteries offered by Speed Partz, Click Here