Lead-Acid Batteries

You’ve seen the basic configuration for a lead-acid cell. This has a solution of sulfuric acid, along with a lead electrode (negative) and a lead-dioxide electrode (positive). These cells are rechargeable.

Automotive batteries are made from sets of lead-acid cells having a free-flowing liquid acid. You cannot tip such a battery on its side, or turn it upside-down, without running the risk of having some of the acid electrolyte spill out. Lead-acid batteries are also available in a construction that uses a semisolid electrolyte. These batteries are sometimes used in consumer electronic devices that require a moderate amount of current. The most common example is an uninterruptible power supply (UPS) that can keep a desktop personal computer running for a few minutes if the utility power fails.

A large lead-acid battery, such as the kind in your car or truck, can store several tens of amperehours. The smaller ones, like those in a UPS, have less capacity but more versatility. Their main attributes are that they can be charged and recharged many times, and they are not particularly expensive.