The Parts of a Lead-Acid Storage Battery
- Lead-acid batteries are so called because the battery uses lead-based alloy electrode plates in an acidic solution to provide electrical power. The negative electrodes in a lead-acid battery are made of lead alloy, whereas the positive electrodes are made of lead dioxide alloy. The electrode plates often use calcium or antimony as a part of the electrode alloy.
- A lead-acid battery contains an aqueous electrolyte solution that is 36 percent sulfuric acid and 64 percent distilled water. This solution reacts chemically with the electrode plates to create a voltage differential between the electrodes.
- Since the voltage at the positive electrode is higher than the voltage at the negative electrode, it would damage the battery if the electrodes touched each other. Therefore, each battery cell requires an electrical isolator -- or separator -- placed between the plates. These separators contain a fiberglass mat that acts as an electrical insulator.
- Lead-acid batteries provide approximately 2.1 volts per cell. Therefore, multiple cells per battery are required to provide automobiles with either six or 12 volts. Similarly, multiple plates are present in each cell so that the battery can provide extra electrical current. Battery plate straps and cell connectors allow multiple electrode plates to be connected together.
A battery plate strap connects several plates together within a single cell. A plate strap will connect all of the lead dioxide plates in a single cell together, or all of the lead plates in a single cell together. This allows each cell to provide more electrical current than a single set of plates.
A battery cell connector allows one battery cell to connect in series to the next cell. When two battery cells are connected in series, it allows the battery to provide voltage equal to the sum of the voltage ratings of both cells. Therefore, a six-volt lead-acid battery will have two battery cell connectors -- one connecting the first cell's negative plates to the second cell's positive plates, and one connecting the second cell's negative plates to the third cell's positive plates.