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Battery charger
This unit charges the batteries until they reach a specific voltage and then it trickle charges the batteries until it is disconnected. . A simple charger equivalent to a AC-DC wall adapter. It applies 300mA to the battery at all times, which will damage the battery if left connected too long. . A battery charger is a device used to put energy into a secondary cell or (rechargeable) battery by forcing...
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This unit charges the batteries until they reach a specific voltage and then it trickle charges the batteries until it is disconnected. . A simple charger equivalent to a AC-DC wall adapter. It applies 300mA to the battery at all times, which will damage the battery if left connected too long. . 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. Types of battery chargers. . Simple. A simple charger works by connecting a constant DC power source to the battery being charged. The simple charger does not alter its output based on time or the charge on the battery. This simplicity means that a simple charger is inexpensive, but there is a tradeoff in quality. Typically, a simple charger takes longer to charge a battery to prevent severe over-charging. Even so, a battery left in a simple charger for too long will be weakened or destroyed due to over-charging. These chargers can supply either a constant voltage or a constant current to the battery. Trickle. A trickle charger is a kind of simple charger that charges the battery slowly, at the self-discharge rate. A trickle charger is the slowest kind of battery charger. A battery can be left in a trickle charger indefinitely. Leaving a battery in a trickle charger keeps the battery "topped up" but never over-charges. Timer-based. The output of a timer charger is terminated after a pre-determined time. Timer chargers were the most common type for high-capacity Ni-Cd cells in the late 1990s for example (low-capacity consumer Ni-Cd cells were typically charged with a simple charger).Often a timer charger and set of batteries could be bought as a bundle and the charger time was set to suit those batteries. If batteries of lower capacity were charged then they would be overcharged, and if batteries of higher capacity were charged they would be only partly charged. With the trend for battery technology to increase capacity year on year, an old timer charger would only partly charge the newer batteries.Timer based chargers also had the drawback that charging batteries that were not fully discharged, even if those batteries were of the correct capacity for the particular timed charger, would result in over-charging. Intelligent. Output current depends upon the battery's state. An intelligent charger may monitor the battery's voltage, temperature and/or time under charge to determine the optimum charge current at that instant. Charging is terminated when a combination of the voltage, temperature and/or time indicates that the battery is fully charged.For Ni-Cd and NiMH batteries, the voltage across the battery increases slowly during the charging process, until the battery is fully charged. After that, the voltage decreases, which indicates to an intelligent charger that the battery is fully charged. Such chargers are often labeled as a V, or "delta-V," charger, indicating that they monitor the voltage change.However, the magnitude of "delta-V" can become small or even nonexistant if (very) high capacity rechargable batteries are recharged. This can cause even an intelligent battey charger to not sense that the batteries are actually already fully charged, and continue charging. Overcharging of the batteries result. A typical intelligent charger fast-charges a battery up to about 85% of its maximum capacity in less than an hour, then switches to trickle charging, which takes several hours to top off the battery to its full capacity. Fast. 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. Pulse. Some chargers use pulse technology in which a pulse is fed to the battery. This DC pulse has a strictly controlled rise time, pulse width, pulse repetition rate (frequency) and amplitude. This technology is said to work with any size, voltage, capacity or chemistry of batteries, including automotive and valve-regulated batteries. With pulse charging, high instantaneous voltages can be applied without overheating the battery. In a Lead-acid battery, this breaks-down stubborn lead-sulfate crystals, thus greatly extending the battery service life.Several kinds of pulse charging are patented. Others are open source hardware.Some chargers use pulses to check the current battery state when the charge
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