Battery Charger Corporate Profiles, Directory, and Market Values

A battery charger is a device used to replenish the electrical charge stored in secondary (storage) batteries. A battery charger applies direct current at a necessary voltage and current to the electrodes of the battery.

It is relatively easy to charge a battery with direct current. All that is necessary is a resistor to adjust and control the rate of charge. Unfortunately, a battery can' t be charged with unmodified alternating current. With a few exceptions, batteries are charged using a "power converter" or transformer and alternating house current (115-volts or 230-volts) or a heat engine (like an internal combustion engine) of an auto. In the first case, AC is converted to DC using a rectifier, with or without a transformer. In the second case, the heat engine drives a DC generator or alternator. In some high capacity industrial battery charging situations, an AC-powered motor is used to operate a DC generator and charger. Battery charger efficiencies are typically 85% to 90%.

• rectifiers
• transformers
• regulators
• microcontrollers.
• packaging

RECTIFIERS

A rectifier is an electrical circuit that converts oscillating current or AC into unidirectional current or DC through the inversion or suppression of alternate half waves. There are at least a dozen battery charger rectifier designs possible. In practice, however, the important battery charger rectifier configurations are tungar rectifiers and selenium/silicon solid-state rectifiers. Silicon diodes are a subcategory of the solid-state rectifier.

• 1. A tungar rectifier consists of a tungar bulb enclosing a tungsten-containing filament. The heated filament ionizes an inert gas in the bulb when AC is applied. Electricity is conducted when the current at the anode is positive and is blocked when the current at the anode is negative.
• 2. In a solid-state rectifier, current passes easily when the polarity of the current is in one direction. In the other direction, resistance is high and current does not easily pass. AC reverses polarity 60 times per second (60 hertz). When connected to a rectifier, half of the AC' s cycle passes through easily and half is blocked.
• 3. A selenium rectifier consists of a disk or plate, usually with four layers: (1) an aluminum base plate; (2) a thin selenium layer; (3) a thin blocking layer (where the conversion to DC actually takes place); and (4) a metal counter electrode.
• 4. A silicon diode rectifier consists simply of a small silicon pellet enclosed by a metal housing. A variety of leads or housing designs is possible. Microelectronic silicon diodes have also been fabricated.