MOTORCYCLE BATTERY TYPES

Traditionally, motorcycles used a lead-acid battery and most still do. Developments in lead-acid batteries have overcome many of the hurdles they originally presented.

But many manufacturers are now turning to lithium-iron-phosphate cells as an alternative (not to be confused with lithium-ion). We also sell them as aftermarket upgrades. But does it matter? Lithium or lead batteries – what’s the difference?

Lead-Acid Batteries

There are three types of lead-acid battery, flooded (or wet cell), AGM (absorbent glass mat), and Gel.

All lead-acid batteries have lead plate electrodes and a liquid electrolyte comprised of distilled water and sulphuric acid. As the battery discharges, the electrolyte becomes less acidic. As the battery charges, the electrolyte becomes more acidic and gives off oxygen and hydrogen.

Lead-acid batteries also have a venting mechanism, even though some are sealed. They have to vent otherwise they would explode because of pressure build-up. The water in the electrolyte turning to gas through the electrochemical charging process creates this pressure.

Conventional flooded/wet cell types of lead-acid batteries are VLA (vented lead-acid) because they constantly vent to the atmosphere through an opening. That is why you must regularly top them up with deionised or distilled water.

AGM and Gel lead-acid batteries are VRLA (valve-regulated lead-acid) or SLA (sealed lead-acid). They vent to a separate chamber via a relief valve in the battery casing if they need to when there is excess pressure from overcharging.

VRLA/SLA batteries are “sealed” or maintenance-free (MF). They keep gases produced when charging, then recombine them when discharging to form water. That’s why there’s no need to top up.

Conventional VLA Flooded (Wet Cell) Batteries

VLA batteries have lead plate electrodes submerged in the electrolyte. They vent directly to the atmosphere, so as they charge and give off gases, the electrolyte level drops. They require frequent checking and topping-up with deionised or distilled water. If the electrolyte level drops too low and exposes the plates to air they will corrode, deteriorate and eventually fail.

Flooded batteries have the least impact resistance and high internal resistance. You must mount them upright. Conventional batteries are user-activated, meaning they are dry-charged at the factory and supplied with a separate acid pack. Retailers add this to the battery before passing it to the customer (unless the customer has an EPP licence allowing the handling of acid).

VRLA AGM Batteries

AGM batteries use an absorbent fibreglass mat between the electrodes which absorbs the electrolyte, so there is no liquid. They have a lower internal resistance than other batteries and this increases the output voltage and reduces charging time, and they discharge less rapidly than conventional flooded (wet cell) batteries.

AGM batteries are also physically stronger (better impact and vibration resistance) than flooded (wet cell) ones. You can mount them at an angle, but how much of an angle depends on the battery itself. 

VRLA Gel Batteries

Gel batteries use silica to turn the electrolyte into a gel. They are physically stronger than flooded batteries, but not as strong as AGM types, and they cope well with vibration. You can mount them at an angle or on their side, but not upside-down. They don’t like to be rapidly discharged by a high current draw, and high charge rates can damage the gel, creating pockets that can lead to corrosion of the plates.

They’re not as good in cold temperatures, but they cope very well with deep discharge. Gel batteries are factory-activated, meaning the factory fills, seals and charges them.

Compared: Wet-Cell, AGM, And Gel Batteries

AGM batteries are the best type of lead-acid battery in terms of starting power, durability, and value. They are worth the extra cost compared to the flooded type and are generally cheaper than gel batteries.

However, note that if your manufacturer specifies the use of a conventional flooded (wet cell) battery and you want to upgrade to an AGM or Gel battery, make sure the charging system can charge at 14.0 volts or more. If it charges at less than 14.0 volts, continue to use a conventional battery.

Lead-Acid vs AGM vs Gel – Pros and Cons

Lead-Acid

Pros: 

• Cheap
• Better recovery from deep discharge
• Good choice for a wide range of requirements

Cons:

• Heavy
• Non-VRLA/SLA types require regular maintenance
• Non-VRLA/SLA types contain corrosive electrolyte that could leak
• Contains lead, so bad for the environment
• Shorter life
• Higher self-discharge rate when not in use (up to 1% per day)
• Longer charge time
• Lose more cranking power in freezing conditions

AGM

Pros:

• High cranking power
• Very resistant to vibration
• Won’t leak
• Quick Charging
• Good cold weather performance

Cons:

• More expensive than Lead Acid
• Heavy
• Requires a specific charger

Gel

Pros:

• Can be mounted on its side
• Sealed/maintenance free
• Resistant to discharge, vibration and sulfation
• Can last up to 4 times longer than lead acid

Cons:

• More expensive than lead acid
• Less cranking power than lead acid
• Slower charging than lead acid
• Requires specific charger