What are your options when replacing a battery on your bike?

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, or sometimes in the larger, bagger type bikes. 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. Tis type of battery is seldom a factor for choice in motorcycle, where the cranking amps requirement is usually quite small, even on large bikes. When in the start mode, most all electronics of the largest draw (lights) are disabled until the engine starts and the alternator has taken over providing current at a much higher rate than the battery alone can.

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. On biles, we seldom get the battery discharged much because we are eihter running or off. Not much time is spent with parking lights or accessories on, except some of the big bruiser bikes that have car sized batteries to start with. (not to mention a zip code of their own!)

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.

Battery Composition or Types we commonly use on bikes!

Batteries are also divided according to their composition.

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 motorcycle 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 bike.

Flooded batteries require the periodic addition of water. (NOT tap water either)


Gel (Gelled Electrolyte)
These batteries are much the same of a flooded battery with one exception, Silica Gel has been added between the lead plates 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 acid is pretty much in a suspended state within the gel matrix.

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) (which is what I just installed A Yuasa YB12AL-A2)
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 absorbed into and contained in the glass mats, there is nothing to spill—even when broken. In this they resemble the Gel types, but without the drawbacks of Gel problems in charging and voids.

Additionally, AGM batteries are also capable of taking much more abuse. (most Harley batteries which are almost bullet proof are AGM)

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. (This is not necessarilt true anymore. An AGM battery that cost $200+ last year was just puchased for $85 at a Kawi dealership! On line prices for the same battery (YB12AL-!2 Yuasa for the EN500) were as low as $50 and shipping)

When it comes time to recharge, the AGM battery charges 2 to 3 times faster than the others. It can also sit for far longer times without being recharged by the alternator, or by keeping it hooked up to a battery maintainer. It will self-discharge (die down just sitting there with no drain) almost a third slower than conventional flooded battery types usually provided by the manufacturer. (the original EN500 was Yuasa's CB12AL-A, 12v, 12 AH)