How does a battery charger work?

Answer 1

A battery charger is an electrical appliance which produces direct current at a voltage high enough to safely fill up a rechargeable battery with new electric charge.

OK, what does that mean?

To be able to explain how they work you will need to know what is inside them. If you have some knowledge of physics and chemistry that would come in handy too, but anyway here goes...

Any item with no moving parts which can produce a direct current flow of electricity is known as a "cell". Every cell contains two different plates. The plates are held fixed and separated from each other. They are placed in a special chemical fluid or paste which conducts electricity. One plate is called the "positive" ("+ve"), the other is called the "negative" ("-ve") . Each plate must be made of a different type of material to the other.

The plates can then react with the special chemical in such a way that an electrical current can be drawn off from the cell. [It may be worth mentioning here that if both plates were made from the same material then no difference in voltage would be produced between them and no current could be taken from the cell. Nor could it be charged up.]

As current is drawn from the cell its plates - and the special chemical in which the plates are placed - all gradually change their chemical composition. The result is that, as current is drawn off, the charge stored in the cell is reduced. Another result is that the voltage given out by the cell drops. If nothing is done to replace the charge that has been taken from the cell then, eventually, a point is reached when no more charge can be taken out. That happens because the chemical composition of the plates and the special fluid can change no further. The cell is then called "flat" or "dead".

The actual types of materials used to make a cell determine the output voltage it produces. The physical size of a cell determines both 1) how much charge the cell can produce during its life and 2) how fast it can release that charge. (The bigger the cell, the higher is the total charge it can produce along with a higher charge release rate.)

That is how all "AA", "AAA" or similar non-rechargeable cells work. Exactly the same kind of process takes place in the cells in a car battery, except that the process is reversible. In other words, the plates and the special chemical can be changed back to almost the same condition as they had when they were first charged-up. In cars, and other vehicles which use a battery, the battery is usually kept charged-up by the vehicle's own standard battery charging system.

If something went wrong (either with the vehicle's charging system, or with the battery itself) then a separate "battery charger" can be used to try to restore the charge. However a worn-out old battery simply won't hold its charge any more and a battery charger won't be able to fix it. The battery would have to be replaced.

A typical ordinary car battery has six cells in it, wired up so that they give a total voltage of around 13 volts when the battery is fully charged and just below about 12 volts when it is "flat". The plates in each cell contain a metal called "Lead" (the element which has the chemical symbol "Pb"), and the special chemical which the plates are immersed in is Sulphuric Acid.

Some battery chargers have a meter to show the current flowing into the battery. The meter is not strictly necessary but is useful because you can see that the battery is being given new charge.

When the battery has taken up all the charge it can hold, the fluid (sulphuric acid in the case of a standard car battery) will start to get warm and a "fizzing" noise may be heard. That "gassing" noise is hydrogen and oxygen gas being released from the fluid.

If that happens the battery charger should be switched off and taken away from the battery. The reason for doing this is because those gases could explode if a spark happened near to the battery or someone leant over it whilst smoking a cigarette!

Some battery chargers have an auto-shut off system to stop any more charge being put into the battery when it is full. That should prevent the cells from gassing but it is really never safe to leave a charger "on" after the battery charging has finished.

A battery charger is a device which uses electric current from an outlet to recharge batteries on electronic devices. Not all batteries are rechargeable however.

Answer 2

Phones have rechargeable batteries inside which need to be charged with a DC voltage (slightly higher than the battery voltage). Simple phone chargers provide this DC voltage. Most of the chargers work as follows. These accept AC voltage from the house hold AC power supply which gets down converted to smaller AC voltage through a transformer and is followed an AC-DC convertor (rectifier). After that there is a filter circuit that cleans the voltage before giving out on the charger pins. This voltage is used for charging the phone. More advaned and well designed phone chargers have semiconductor IC based regulators, convertors for clean and efficient AC-DC conversion and have short circuit protection built-in. - Neeraj Sharma

Answer 3

it is basically a rectifier circuit with regulated output .when you connect it to socket it converts 240 v AC to 3.7 Volt or (required) D.C regulated and charge the battery of mobile phones. when charging done there are comparator circuit to checking simultaneously and cut- of the output of charger and hence it prevent from overcharging the battery.

Answer 4

The LTC1732 is a complete constant-current/constantvoltage

linear charger controller for batteries. Charge current

can be programmed with 7% (max) accuracy using external

sense and program resistors. An internal resistor

divider and precision reference set the final float voltage

with 1% accuracy. The SEL pin allows users to charge

either 4.1V or 4.2V cells.

When the input supply is removed, the LTC1732 automatically

enters a low current sleep mode, dropping the battery

drain current to 7mA. An internal comparator detects the

end-of-charge (C/10) condition while a programmable

timer, using an external capacitor, sets the total charge

time. Fully discharged cells are automatically trickle charged

at 10% of the programmed current until cell voltage

exceeds 2.457V.

Answer 5

you plug it in the wall, plug the other end in the phone, turn it on at the wall and HEY PRESTO!!!!!!!!!!!!!!!

Answer 6

You plug it in and the power flows through to the cell phone battery.