Joule Thief to Squeeze Out the Last Bit of Energy from a Single-Cell Electric Battery


To explain a joule thief or a blocking oscillator in simple terms, it is an electric circuit that you can use to extract any remaining power in batteries that are normally considered completely drained or dead. Typically, a battery is discarded after it “dies,” which means that it cannot power any devices anymore. However, the battery is not completely discharged. The truth is that the voltage produced by the weak battery is no long strong enough to power a device.

This is where the joule thief comes to play. This device stimulates the remaining voltage in the battery so that it becomes strong enough to power some devices continuously for certain periods of time.

A joule thief can be described as a voltage booster. It is a small device that is low-cost which can be also very easy to build. Usually, it is used to drive light loads. With a joule thief, you can squeeze out every last bit of energy in a single-cell electric battery even after the battery is considered completely discharged. It works by switching the transistor in the battery rapidly. If you are looking for a more constant output of voltage, you can give the joule thief a closed-loop control, which works by switching transistors and repeating oscillations.