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Discussion of 1.2V vs. 1.5V Batteries

A careful look at the labels on household batteries reveals an interesting difference between different kinds: for the same battery type, such as AA, C or D, some are rated at 1.2 volts, and others are rated at 1.5 volts. A battery̵7;s chemistry affects its voltage, although you may not notice the difference in normal use.

Chemistry
- A battery is an electrochemical device having two electrodes, one positive and one negative, made of different metals and immersed in a electrolyte solution. Household batteries come in several different chemistries, including alkaline, carbon-zinc, nickel-metal hydride and nickel-cadmium. Alkaline and carbon-zinc batteries are 1.5 volts, and nickel-metal hydride and nickel-cadmium are 1.2 volts.
Rechargeable versus Disposable
- You do not recharge disposable batteries, such as the alkaline and carbon-zinc types; you typically use them until they become discharged, then dispose of them. These batteries are rated at 1.5 volts when fresh, and their voltage slowly declines as you use them. A flashlight, for example, will dim as its batteries lose voltage. Rechargeable batteries, such as nickel-cadmium and nickel-metal hydride, are rated at 1.2 volts when fresh. After they discharge, you can place them in a recharger for a few hours and reuse them. These batteries also lose voltage as they discharge, but the voltage returns after a recharge.
Disposal
- Most household battery formulations of either 1.2 or 1.5 volts are safe to place in the trash; however, due to concerns of concentrated battery chemicals in landfills, recyclers encourage you to drop used batteries into a collection bin designated for batteries. The one exception is nickel-cadmium, because cadmium is a heavy metal and poses other environmental hazards. When they no longer recharge, take them to a hazardous waste facility for disposal.
Use
- In flashlights, a higher voltage makes a brighter light, so a 1.2-volt battery will make the flashlight somewhat dimmer. In a motorized toy or appliance, a higher battery voltage makes the motor run faster; the 1.2-volt battery will have a slight disadvantage with motor speed. Some electronic items, such as digital cameras, have voltage regulation, so the device sees the same voltage regardless of battery type. However, a battery with a higher voltage will power the device longer than one with a lower voltage.

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