Battery Construction: Notes

2013 Mini Cooper Countryman, Standard TransSECTION Notes
WARNING: This page does not describe the selected car, but rather 208 other vehicles, including the 2010 BMW Z4, 2010 BMW X6 M, 2010 BMW X6, 2010 BMW X5 M, and 2010 BMW X5. However, it is still accessible from the selected car via links, so may be relevant.

Modern automotive batteries are made of cases (usually plastic) containing alternating plates of Lead and Lead Dioxide (or Lead Oxide) separated by insulators. These alternating plates are connected in series to produce a voltage of 12.6 volts, or about 2.1 volts for each set of Lead and Lead Dioxide plates. The negative terminal is connected to a Lead Dioxide plate and the positive terminal to a Lead plate.

Fig 1: Identifying Battery Plates
G03390173Courtesy of BMW OF NORTH AMERICA, INC.

The plates are covered with electrolyte which is a solution of 35% Sulfuric acid and 65% Water.

Fig 2: Cross Sectional View Of Battery
G03390174Courtesy of BMW OF NORTH AMERICA, INC.
  1. Plastic container.
  2. Positive and negative internal plates made of lead.
  3. Plate separators made of porous synthetic material.
  4. Electrolyte which is a dilute solution of Sulfuric acid and water better known as Battery Acid.
  5. Lead terminals which are the connection point between the battery and whatever it powers.
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