Description
ABSTRACT
A battery charger is an electrical device employed for charging batteries. These batteries that are usually charged by battery charger are the storage batteries also known as “accumulator” the battery charger changes. The alternating current forms the power line into d.c suitable for charging.
When the battery is fully changed, is up to it’s maximum, 12 volt, the charger with automatically stop changing with the help of the contact relay, the transistor and the zener diode when bend the current back to the system, and the system have the ability to indicate when the battery is charging or not, when the battery is empty or fully charged.
CHAPTER ONE
1.1 INTRODUCTION
A battery charger is an electrical device employed in charging batteries that are usually charged by battery charges are the storage batteries also known as “accumulators”.
The charger is made up of various electrical and electronics component which for the purpose of clanty are group into your basic unit they are:
The power supply units
The smoothing circuits
The regulating unit and
Regulated D.C charging units
A Battery charger comes in various designs and voltage. The choice of a particular and of charger that depends largely int eh size of battery or battery or batteries which on mterds to charge the mini battery changer could be used to charge batteries whose voltage ranges from 6 – 12 volts. The bigger battery changes are for batteries with voltage ranging from 12 – 48 volts. These are the heavy duty batteries.
The battery charge is built in such a way that it delivers a constant value of d.c current into the battery it is charging in the opposite direction from which current flows on the batteries during discharge one cannot successfully design a battery charge with out a fundamental understanding of the accumulator because it also makes up the operation.
1.2 OBJECTIVES OF THE PROJECT
The objective of the project is to design a device that will recharge 12v car lead acid battery when discharged, a battery charger that will shut off the charging process once the battery attains full charge using lm317. This prevents overcharging of the battery so that, the charger can be left unattended.
1.3 SIGNIFICANCE OF THE PROJECT
This device charges 12v acid battery mainly, however, if the output voltages are adjusted can be used to charge battery of lower or higher voltages. Apart from charging batteries, this device can also be used as a battery level monitor due to the battery level feature it contains.
1.4 ADVANTAGES OF AUTOMATIC BATTERY CHARGER
The main advantages of this battery charger over other chargers is the ability of the charger to indicate battery charging levels and also the ability to stop charging when the battery is fully charged and resume charging when the battery level drops below the set level.
1.5 FEACTURES OF AUTOMATIC BATTERY CHARGER
Features of automatic battery charger are as below:
- Automatic battery charger has an indicator to indicate when the battery is fully charged
- It has a manually operated switch that is used to ON and OFF the entire system.
- It consumed less current but generate high current to the load.
1.6 APPLICATION OF THE PROJECT
Battery charger is used in the following devices for the purpose of recharging device batteries:
- It is used in inverter
- It is used in cellphone
- It is used in Solar energy system
- It is used in vehicles
- It is used in an uninterruptible power supply(UPS), etc.
1.7 LIMITATION OF THE PROJECT
The only problem with this device is that it takes longer time to recharge car battery because of the low current output, and it is design only for a 12 battery.
CHAPTER TWO
2.0 LITERATURE REVIEW
2.1 HISTORICAL BACKGROUND OF BATTERY CHARGER
The history of battery chargers is long but interesting. Chargers and rechargeable batteries date back to the 1800′s. the concepts and designs have taken on new meaning in the era of portable electronics. With new technology there is charger for almost everything imaginable. The devices are widely used, and their progression over time is huge.
The first battery charger was for the car. The idea came from Gaston Plante, a French physicist that invented the lead acid cell battery in 1859. Though, it was years later that the idea became what it is today, he was the pioneer of the concepts. It was Waldemar Jungner that discovered the Nickel-Cadmium battery in 1899. The Swedish scientist developed this product and it was on the market by 1906. These men of science had ideas before their times. Imagine what they would think of today progress of their once simple ideas.
Chargers for lithium-Ion batteries are almost a necessity in society today. Being used in everything from mobile phones, to laptops, and many other portable devices, they are a must for most. They were introduced in 1991 by Sony. The twenty year phenomenon in the making was originally theorized in the 1970s. Nickel-Metal Hydride was created in the 1980s. This battery comes in all sizes and is probably the most common household battery used today.
Battery charging devices are a common item to own. They come into play with the invention of rechargeable batteries. The idea behind it all was not only to save money but to save time. The average person can save hundreds of dollars per year by using rechargeable batteries with a battery charger. That same person can also save a great deal of time. The more modern designs were also intended to help save the environment by reducing waste and eliminating unnecessary uses of extra energy. The researchers of the pasts would be proud of where the designs have led.
The thought of not having a battery charger for practically everything you own has probably never crossed your mind, but let it for a moment. if you did not have a mobile phone charger or if you weren’t able to recharge those AA batteries for the digital camera what would you do? The concepts may not all have been intended for what they have become, but the transition over time is surely remarkable. Chargers and rechargeable batteries in yesterday’s world are the building blocks for today’s models. So much has developed in the last hundred years in this science. When one looks back at the past and sees what has become, one can help but to think of the future and wonder what will be.
2.2 REVIEW OF BATTERY CHARGER
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 charging protocol depends on the size and type of the battery being charged. Some battery types have high tolerance for overcharging and can be recharged by connection to a constant voltage source or a constant current source; simple chargers of this type require manual disconnection at the end of the charge cycle, or may have a timer to cut off charging current at a fixed time. Other battery types cannot withstand long high-rate over-charging; the charger may have temperature or voltage sensing circuits and a microprocessor controller to adjust the charging current, and cut off at the end of charge. A trickle charger provides a relatively small amount of current, only enough to counteract self-discharge of a battery that is idle for a long time. Slow battery chargers may take several hours to complete a charge; high-rate chargers may restore most capacity within minutes or less than an hour, but generally require monitoring of the battery to protect it from overcharge. Electric vehicles need high-rate chargers for public access; installation of such chargers and the distribution support for them is an issue in the proposed adoption of electric cars.
2.3 REVIEW OF DIFFERENT TYPES OF BATTERY CHARGERS
Simple chargers
A simple charger works by supplying a constant DC or pulsed DC power source to a 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.
Simple AC-powered battery chargers have much higher ripple current and ripple voltage than other kinds of battery supplies. When the ripple current is within the battery-manufacturer-recommended level, the ripple voltage will also be well within the recommended level. The maximum ripple current for a typical 12 V 100 Ah VRLA battery is 5 amps. As long as the ripple current is not excessive (more than 3 to 4 times the battery-manufacturer-recommended level), the expected life of a ripple-charged VRLA battery is within 3% of the life of a constant DC-charged battery.
Fast chargers
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 standard overnight chargers if used with standard NiMH cells that do not have the special control circuitry.
Inductive chargers
Inductive battery chargers use electromagnetic induction to charge batteries. A charging station sends electromagnetic energy through inductive coupling to an electrical device, which stores the energy in the batteries. This is achieved without the need for metal contacts between the charger and the battery. It is commonly used in electric toothbrushes and other devices used in bathrooms. Because there are no open electrical contacts, there is no risk of electrocution.
A “smart charger” should not be confused with a “smart battery”. A smart battery is generally defined as one containing some sort of electronic device or “chip” that can communicate with a smart charger about battery characteristics and condition. A smart battery generally requires a smart charger it can communicate with (see Smart Battery Data). A smart charger is defined as a charger that can respond to the condition of a battery, and modify its charging actions accordingly.
Some smart chargers are designed to charge:
- “smart” batteries.
- “dumb” batteries, which lack any internal electronic circuitry.
The term “smart battery charger” is thoroughly ambiguous, since it is not clear whether the adjective “smart” refers to the battery or only to the charger.
The output current of a smart charger depends upon the battery’s state. An intelligent charger may monitor the battery’s voltage, temperature or time under charge to determine the optimum charge current and to terminate charging.
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 ΔV, “delta-V,” or sometimes “delta peak”, charger, indicating that they monitor the voltage change.
The problem is, the magnitude of “delta-V” can become very small or even non-existent if (very) highcapacity rechargeable batteries are recharged. This can cause even an intelligent battery charger to not sense that the batteries are actually already fully charged, and continue charging. Overcharging of the batteries will result in some cases. However, many so called intelligent chargers employ a combination of cut off systems, which should prevent overcharging in the vast majority of cases.
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.
Motion-powered charger
Several companies have begun making devices that charge batteries based on regular human motion. One example, made by Tremont Electric, consists of a magnet held between two springs that can charge a battery as the device is moved up and down, such as when walking. Such products have not yet achieved significant commercial success.
Pulse chargers
Some chargers use pulse technology in which a series of voltage or current pulses is fed to the battery. The DC pulses have 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.[7] With pulse charging, high instantaneous voltages can be applied without overheating the battery. In a Lead–acid battery, this breaks down 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 charger is first connected, then use constant current charging during fast charging, then use pulse charging as a kind of trickle charging to maintain the charge.
Some chargers use “negative pulse charging”, also called “reflex charging” or “burp charging”. Such chargers use both positive and brief negative current pulses. There is no significant evidence, however, that negative pulse charging is more effective than ordinary pulse charging.
Solar chargers
Solar chargers convert light energy into DC current. They are generally portable, but can also be fixed mount. Fixed mount solar chargers are also known as solar panels. Solar panels are often connected to the electrical grid, whereas portable solar chargers are used off-the-grid (i.e. cars, boats, or RVs).
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.
Trickle chargers
A trickle charger is typically a low-current (5–1,500 mA) battery charger. A trickle charger is generally used to charge small capacity batteries (2–30 Ah). These types of battery chargers are also used to maintain larger capacity batteries (> 30 Ah) that are typically found on cars, boats, RVs and other related vehicles. In larger applications, the current of the battery charger is sufficient only to provide a maintenance or trickle current (trickle is commonly the last charging stage of most battery chargers). Depending on the technology of the trickle charger, it can be left connected to the battery indefinitely. Some battery chargers that can be left connected to the battery without causing the battery damage are also referred to as smart or intelligent chargers.
Universal battery charger–analyzers
The most sophisticated types are used in critical applications e.g.: military or aviation batteries. These heavy-duty automatic “intelligent charging” systems can be programmed with complex charging cycles specified by the battery maker. The best are universal (i.e.: can charge all battery types), and include automatic capacity testing and analyzing functions too.
USB-based chargers
Since the Universal Serial Bus specification provides for a five-volt power supply, it is possible to use a USB cable as a power source for recharging batteries. Products based on this approach include chargers for cellular phones, portable digital audio players, and tablet computers. They may be fully compliant USB peripheral devices adhering to USB power discipline, or uncontrolled in the manner of USB decorations. Although portable solar chargers obtain energy from the sun only, they still can (depending on the technology) be used in low light (i.e. cloudy) applications. Portable solar chargers are typically used for trickle charging, although some solar chargers (depending on the wattage), can completely recharge batteries. Other devices may exist, which combine this with other sources of energy for added recharging efficacy.
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