A battery-powered amplifier is a device that is designed to boost audio signals using electricity from portable battery sources. There are a number of different types of battery-powered amplifiers, each of which are designed for specific purposes. Instrument amplifiers can be designed to run on battery power, and can operate for about four to eight hours, depending on the type of batteries and how loud the volume is set. Car audio amplifiers can also be battery-powered, since they are designed to run on around 12 volts of direct current (DC). Most headphone amplifiers are also battery-powered, often with compact nine-volt batteries.
Amplifiers are devices that contain some type of amplification circuitry, an input and an output. A signal is fed into the input, boosted by the amplification circuitry and made available to the output. Many amplifiers, such as instrument and home theater amps, are designed to operate on the alternating current (AC) electricity available from municipal power grids. A battery-powered amplifier performs the same basic function as those that run on AC, but it is more portable due to the ability to run on DC power sources.
One common type of battery-powered amplifier is designed for use with musical instruments, such as guitars. These amplifiers have similar designs to regular instrument amps, but they are more portable and can be used in areas that lack electricity. Battery-powered instrument amps typically run on either nickel cadmium (NiCad) or nickel-metal hydride (NiMH) rechargeable batteries. The length of time that this type of battery-powered amplifier can be used depends on factors such as the battery capacity and the volume settings on the amp. It is also possible to run a regular instrument amp on battery power if an inverter is used.
Car audio systems also make use of battery-powered amplifiers, since the electrical systems present in automobiles put out about 12 volts DC. In practice these amplifiers are actually powered by an alternator whenever a vehicle is running, but pure battery power can be used when the engine is shut off. It is also possible to connect this type of amplifier directly to a 12-volt battery source to create a portable audio system without a vehicle.
Some battery-powered amplifiers are also designed for use with headphones. These amplifiers are typically very small, so that they can be carried along with portable music devices. Due to size constraints, this type of battery-powered amplifier often runs on a compact nine-volt battery instead of multiple 1.5 volt batteries. Headphone amps sometimes also have an alternate power jack that can be plugged into AC power.