When a lead-acid battery is charged, the lead sulfate on the plates is converted back into lead oxide and lead. This process is called “charging.” When the battery is discharged, the lead oxide and lead on the plates react with the sulfuric acid to form lead sulfate. This process is called “discharging.” Lead-acid batteries have several advantages.
A lead-acid battery has electrodes mainly made of lead and lead oxide, and the electrolyte is a sulfuric acid solution. When a lead-acid battery is discharged, the positive plate is mainly lead dioxide, and the negative plate is lead. The lead sulfate is the main component of the positive and negative plates when charging.
Lead–acid batteries may be flooded or sealed valve-regulated (VRLA) types and the grids may be in the form of flat pasted plates or tubular plates. The various constructions have different technical performance and can be adapted to particular duty cycles. Batteries with tubular plates offer long deep cycle lives.
Lead acid batteries are a simple technology, and have changed little since the 1800s. Battery banks for offgrid use are expensive, making home made battery banks an attractive option.
Batteries use 85% of the lead produced worldwide and recycled lead represents 60% of total lead production. Lead–acid batteries are easily broken so that lead-containing components may be separated from plastic containers and acid, all of which can be recovered.
Sulfation prevention remains the best course of action, by periodically fully charging the lead–acid batteries. A typical lead–acid battery contains a mixture with varying concentrations of water and acid.