Lead Acid Batteries: Some keys to long service life

Some keys to long service life By Joe Escobar Some mechanics think that maintaining lead acid batteries is a magic craft that relatively few have mastered. They just can't figure out why batteries aren't lasting as long as they should. They...


Lead Acid Batteries
Keys

Some keys to long service life
By Joe Escobar

Some mechanics think that maintaining lead acid batteries is a magic craft that relatively few have mastered. They just can't figure out why batteries aren't lasting as long as they should. They are quick to blame the battery manufacturer claiming they were sold a defective battery. That may be the case in a very slim number of cases, but the fact of the matter is other factors come in to play that can seriously decrease the service life of your lead acid battery. Knowing the factors and how to counteract them can give you the longer service life you have been looking for.

In order to understand the factors that lead to shorter service life in your lead acid battery, it is important to have a basic knowledge of battery theory and construction. But first, lets go over some important safety precautions.

Safety precautions
There are several safety precautions that should be observed when working with lead acid batteries.

Wear splash proof goggles and protective clothing. Use care not to spill or splash the electrolyte. It is an acid and can cause severe burns to the skin.

When lifting a battery, you should wear some form of back support and avoid bending or twisting in awkward positions. Also avoid putting excess pressure on the end walls of the battery, since this could cause electrolyte to escape through the vents. When possible, use a battery lifting strap or lift it with your hands placed at opposite corners.

If electrolyte is spilled or splashed on your clothing or body, it should be neutralized immediately with a solution of baking soda and water and then rinsed with clean water.

Getting electrolyte in your eyes can be extremely dangerous. If this happens, force the eye open and flood it with cool, clean water for at least five minutes. Contact a doctor immediately. Do not add any eye drops or other medication unless advised to do so by the doctor.

If the electrolyte is taken internally, drink large quantities of water or milk followed with milk of magnesia, beaten egg, or vegetable oil. Call a doctor or poison control immediately.

If preparing electrolyte from concentrated sulfuric acid, always pour the acid into the water. Never pour water into an acid because a violent chemical reaction will result.

Keep all open flames, sparks, burning cigarettes, and other ignition sources away from batteries at all times.

Avoid the use of uninsulated tools. If uninsulated tools are used, severe arcing may result with possible harm to personnel and damage to the tools and cells within the battery. All jewelry including watches, bracelets, and rings should be removed as they may fuse themselves to the connectors and cause severe burns.

Finally, separate areas should be used for lead acid and NiCad battery maintenance to prevent electrolyte contamination in the batteries.

Basic theory
Lead acid batteries are named after the two major components of the battery - lead and acid. More specifically, the battery is made up of positive plates of lead peroxide (PbO2), negative plates of pure spongy lead (Pb), and a liquid electrolyte between the plates of sulfuric acid (H2SO4) and water (H2O). The sulfuric acid and water are mixed in a ratio so that a specific gravity of 1.285 to 1.295 is achieved for a fully charged battery.

Electrochemical reaction
All batteries use an electrochemical reaction to deliver current. The first battery created by Alessandro Volta in 1800 was constructed of a stack of alternating layers of zinc, blotting paper soaked in salt water, and silver. This arrangement was known as a voltaic pile and is the basis of battery construction today. The electrochemical reaction that takes place in a lead acid battery can be written in a formula as follows:

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