How does Sulfation Drain a Battery?

Due to chemical interactions inside a lead battery it must be used on a regular basis or sulfation will occur. Sulfation interferes with the ability of the battery to accept, hold and deliver a charge, and left unchecked will render the battery useless far short of its designed life. In understanding how, and under what circumstances sulfation takes place, one can take measures to avoid it and prolong battery life by years. This is not only good for the pocketbook, but for the environment.

In basic terms, a common acid battery consists of a series of oppositely charged lead and lead oxide plates which divide cells. Battery cells are filled with a mixture of 65% distilled water and 35% sulfuric acid, or electrolyte solution. Electrolyte produces electrons. While under charge electrons move between the plates discharging energy in the form of volts. The lead plates convert this energy into electricity. Each cell can produce about 2.1 volts of charge, therefore a 12.6-volt battery, for example, requires six cells.

Sulfation occurs when the battery sits for long periods of time and the electrolyte solution begins to break down. Sulfur in the solution leaches from the electrolyte, sticking to the lead plates as converted lead sulfuric crystals. These crystals coat the plates preventing them from doing their job at the next crank. Compounding the problem, the electrolyte solution becomes weaker because it is lacking the sulfuric acid that has converted to crystals. This equation reduces the ability of the battery to deliver and accept a charge.

Stages of sulfation include an initial form that might reduce quick starting, but will be absorbed back into the electrolyte when charged. With more time, stage one progresses into stage two sulfation, wherein small crystals begin to form on the plates. At this point the battery might not start the vehicle, and will require a greater charge to break the crystals free. If the battery sits long enough, stage two sulfation will advance into stage three, resulting in a non-chargeable battery. The lead sulfuric crystals of stage three sulfation can grow so large as to cause the battery case to bow.

To keep sulfation from occurring, a battery need only be maintained in a fully charged state. For those vehicles and crafts used on a daily or semi-daily basis, this isn’t a problem. However, pleasure boats, personal aircraft, recreational vehicles, off-road vehicles, and motorcycles that are used occasionally will develop battery sulfation, barring preventative measures.

To slow this process, some people disconnect the battery from the vehicle when not in use, but sulfation and self-discharge still occur. A better, more convenient and effective solution is to use a device called a battery conditioner. A battery conditioner will keep the battery fully charged between uses, without overcharging it. Battery Minder and Battery Tender are examples of two such products, designed specifically to prevent sulfation and extend battery life by as much as several years.