All vehicles have a charging system which provides for their electrical needs, such as ignition, lights, heater and electrical accessories, while the , is running, as well as charging the . It consists of a generator, driven by a , and an control system. Old made five or six years earlier are fitted with an alternator which is a form of generator for charging purpose while some commercial vehicles have different types known as the dynamo.
In both the alternator and the dynamo, electricity is generated in the same way as it is at a power station. Either, coils of are moved near a stationary magnet (dynamo), or the magnet is moved near coils of (alternator). In each case, the moving lines of magnetic generate electricity in the coils of . The amount of electricity generated depends on the speed at which the coils and magnet move relative to each other, how close they are to each other, the strength of the and the number of turns of in each coil.
As the speed of a changes continually, but the electrical requirements for such items as headlights or a heated rear window are constant, a method of controlling the generator output is necessary. That can be achieved by using an control system to alter the strength of the .
Practically, an alternator can produce higher output for longer periods of time than a dynamo. This is because the generating windings in an alternator are stationary and are not restricted in size, nor are they as difficult to cool as those of a dynamo, which rotates in its armature.
In practice, both the alternator and the dynamo start to produce a useful current output at armature speeds in excess of 1,500rpm. However, the dynamo armature is limited to about 6,000rpm. That is because of the effects of centrifugal on its complicated windings, and also because at , constant brush contact with the commutator is difficult to achieve.
The armature, or rotor, in an alternator is not as complicated and can be turned at least three times as fast as a dynamo. This means that the drive-belt pulley fitted to a dynamo has to be quite large to prevent the armature turning too quickly, and the engine must be turning quite fast for it to produce a useful current. The alternator is fitted with a much smaller pulley and can produce a useful current at tick-over speeds.
HOW TO CONNECT
In winter, when cold weather makes the battery less efficient, a car used on many short stop-start journeys will consume a great deal of battery power each time the starter is operated, but the may not travel far enough for the generator to put back the lost energy.
Under these conditions, a mains-operated charger that puts a ‘trickle’ of current into the while the is packed overnight, will do the same job as a generator. As most home chargers have a low output, it is not necessary to the filler caps i.e the vent cover. New batteries should not have their vents or covers removed during charging since the electrolytes could overflow. Inflammable is given off through the vent holes during charging, so charging should be carried out only in a well-ventilated area, and anything likely to cause a spark should be at least six feet away from the .
Here, the has been removed from a , but charging can, if required, be carried out with the connected up and in position on the . Below are steps to be followed in charging of the :
- the electrolyte level and top it up if necessary, replace the filler plugs or vents cover.
- Connect the charger clips to the terminals. The positive clip (+) usually joined to a red cable goes to the positive (+) terminal. The is joined to a black cable clamped on the negative terminal.
- in the charger to the mains and switch it on. It should indicate the rate of charge on a dial or illuminate a working lamp. Most chargers make a humming sound. If the charger does not , switch it off and its fuse. If this has blown, that the connections on the are correct. Accidentally touching them together when the charger is working will blow the fuse.
- When charging is complete, switch off the charger.
- After the switching it off, disconnect the clips from the terminals. A ‘live’ charger should not be disconnected at the terminals since it can cause a spark at that moment and cause the being released to explode.
Originally posted 2018-10-07 18:59:59.
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