Battery

The energy stored in a battery (or its capacity) is expressed in watt-hours (Wh). For historical reasons, the rated voltage in volts (V) and the charge in ampere-hours (Ah) are sometimes also stated. In this case, the energy stored in the battery is calculated by multiplying the voltage by the charge.

Unfortunately, there are very few areas of technology where manufacturer’s data are as confusing as with battery capacity. For example, you might think that a battery specified as 12 V and 100 Ah, which therefore stores 1200 Wh of energy in nominal terms, should be able to deliver 100 A of current, or 1200 W of power, for one hour. However, you would be wrong.

As a result of the internal resistance of the battery, the available capacity falls off with rising current. This effect is especially dramatic in the case of lead-acid batteries.

The first battery was created by Alessandro Volta in 1800. To create the Volta battery, he made a stack by alternating layers of zinc, blotting paper soaked in salt water, and silver. This arrangement was known as a voltaic pile. The top and bottom layers of the pile must be different metals. If you attach a wire to the top and bottom of the pile, you can measure a voltage and a current from the pile. The pile can be stacked as high as you like, and each layer will increase the voltage by a fixed amount. In the 1800s, before the invention of the electrical generator (the generator was not invented and perfected until the 1870s), the Daniell cell was extremely common for operating telegraphs and doorbells.

However, evidence of batteries dates back to over 2000 years ago. In 1938, Wilhelm Konig discovered in Iraq a 5 inch pottery jar containing a copper cylinder encased in an iron rod. This is believed to be an ancient form of battery.

All batteries are considered hazardous waste in California when they are discarded. This includes all batteries of sizes AAA, AA, C, D, button cell, 9 Volt, and all other batteries, both rechargeable and single use. All batteries must be recycled, or taken to a household hazardous waste disposal facility, a universal waste handler (e.g., storage facility or broker), or an authorized recycling facility.

Hazardous waste regulations designate a category of hazardous wastes called “universal waste.” This category includes many items, batteries, fluorescent lamps, cathode ray tubes, instruments that contain mercury, and others.

We seem to take batteries for granted these days, barely giving them a second thought. Most gadgets need batteries in one form or another, and most batteries are not great for the environment. Rechargeable batteries reduce the number of one-use batteries that we use, but rechargeable batteries still use harmful materials.

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