Specifications of China manufacturer 12v 7Ah VRLA lead acid maintenance free motorcycle battery

When looking at how a lead acid battery works, it is necessary to look at the basic components. The battery has comparatively few components - essentially there are four main elements:

Positive plate: This is covered with a paste of lead dioxide.

Negative plate: This is made of sponge lead.

Separator: This is an insulating material between the two plates, but it allows the electrolyte and the ions into it to enable conduction without the two plates touching.

Electrolyte: This consists of water and sulphuric acid

These constituents are all contained within a plastic container which acts to keep the electrolyte in and the battery together.

The overall battery will normally consist of several cells placed in series to give the required voltage as each cell is capable of providing an EMF of 2.1 volts.

In order to enable the basic lead acid cell to produce a voltage, it must first receive charge. The voltage applied to provide this must be greater than the 2.1 volts to enable current to flow into the cell. If it were less than this, charge would actually flow out of it.

Once charged, the cell or battery will be able to provide charge to external circuits, often operating over several hours dependent upon the drain on the cell or battery.

Valve Regulated Lead Acid (VRLA) Batteries

Also called Sealed Lead Acid (SLA) batteries.

This construction is designed to prevent electrolyte loss through evaporation, spillage and gassing and this in turn prolongs the life of the battery and eases maintenance. Instead of simple vent caps on the cells to let gas escape, VRLA have pressure valves that open only under extreme conditions. Valve-regulated batteries also need an electrolyte design that reduces gassing by impeding the release to the atmosphere of the oxygen and hydrogen generated by the galvanic action of the battery during charging. This usually involves a catalyst that causes the hydrogen and oxygen to recombine into water and is called a recombinant system. Because spillage of the acid electrolyte is eliminated the batteries are also safer.