A battery charger is a device used to put energy into a secondary cell or (rechargeable) battery by forcing an electric current through it.



The charge current depends upon the technology and capacity of the battery being charged. For example, the current that should be applied to recharge a 12 V car battery will be very different from the current for a mobile phone battery.



Fast Charger Fast chargers make use of control circuitry in the batteries being charged to rapidly charge the batteries without damaging the cells' elements. Most such chargers have a cooling fan to help keep the temperature of the cells under control. Most are also capable of acting as a standard overnight charger if used with standard NiMH cells that do not have the special control circuitry. Some fast chargers, such as those made by Energizer, can fast-charge any NiMH battery even if it does not have the control circuit.



Battery Charger rate This is often denoted as C and signifies a charge or discharge rate equal to the capacity of a battery divided by 1 hour. For example C for a 1600 mAh battery would be 1600 mA (or 1.6 amps). 2C is twice this rate and 1/2C is half the rate.



Battery charger Applications Since a battery charger is intended to be connected to a battery, it may not have voltage regulation or filtering of the DC voltage output. Battery chargers equipped with both voltage regulation and filtering may be identified as battery eliminators.



What Should I Consider When Buying a Battery Charger?

When it comes to choosing a battery charger, there are so many options that it can be intimidating to choose among them. Following a few rules will guarantee that you choose a battery charger that will meet your needs and provide top quality service for years to come. A classic battery charger can handle either NiMH or NiCad batteries. A NiMH charger usually works with NiCad cells, but not vice versa. Most battery chargers are designed to work with AA or AAA batteries.



Certain electronic products require a special format battery charger, which is usually provided by the manufacturer. The average battery charger has a capacity of either four or six batteries. Ideally, you should have at least an extra pair of charged batteries on hand at all times, so make sure your charger can handle the load.



The typical battery charger is powered via an AC outlet. Smaller units plug directly into the outlet, making them extremely convenient for people on the go. Because they are designed with travelers in mind, these chargers usually work with both 100 and 220 volt outlets without the need for an adapter. Cheaper chargers require an external converter in the form of a power brick, which sends electricity to the charger via a power cord. This type of charger is much cheaper but also inconvenient, and it usually cannot handle 220 volts unless an expensive adapter is added.



One feature worth spending extra money on is a charger control. An expensive battery charger has an intelligent microprocessor that switches the charger off when the batteries are fully charged. It can also recognize how much charge is originally in the batteries and only add whatever's needed. Cheaper chargers, on the other hand, charge batteries for a fixed length of time, which can overcharge the battery and shorten its life. A simple LED is typically used to indicate when the charge cycle is complete.