Project - Analysis of a practical automotive wiring circuit

Ques1.

Ques 2.
Purpose & Working of`:

Battery:
It is a combination of cells (in parallel & Series) to provide equivalent voltage output, 12V in this case. The combination & arrangement of cells are important to define the capacity of the battery in terms of Ah. For example for a 12V Eq. battery, if two series cell row are added in parallel (both of 24V each), in this case the output is 12V but the capacity (Ah) is increased to twice.
Battery are used to provide potential difference on various application to make the use out of it. For a given voltage by battery, Current will be drawn as per the resistance offered by the application as per Ohm's law.

Ammeter:

It is a device to measure current flowing through the circuit. Generally it is added in series to measure the current since it provides very less resistance so has negligible impact on the circuit. Ammeters are of various kinds, the mechanical types are based on the relation of current flow direction, it's magnetic field & physical forces due to it as per fleming's left hand rule, So the coil / magnet movement is calibrated in a way to point the actual current flowing. Whereas the Digital types used these days uses shunt resistors which are then connected to apotentiometer which is again calibrated to give the current readings accordingly.
Ammeters are very important device as high current can lead to high heat generation hence various loss.

Starter:

In automobile electrical circuit diagram as shown above the Starter is a device used to start a combustion cycle in an IC engine. In a 4-stroke engine, to start with the first 2 strokes are given by the starter itself and then afterwards it becomes self-driven. The starter consists of three main sub-components, the solenoid valve (which connects/disconnects the DC motor with the battery), the DC Motor (driven by the battery is connected to a drive shaft-Clutch mechanism to provide it the desired torque), the drive shaft-clutch setup which is connected to the fly-wheel/crank shaft in a uni-directional order.
So, to start an IC engine, once the ignition key is given, the solenoid valve switches the Battery to the DC motor, which rotates the drive-shaft and then this torque is transfered to the crank-shaft to initiate the combustion first two strokes. Once the engine starts it gets diengaged with the starter due to the clutch action.

Ques.3

Generally the fuse rating should be higher than the peak Current drawn from the battery, So if the total load is 10A from the battery, we can take 13~15A rated fuse.

Ques.4
If 500W is the load,
Considering that 10A is max current drawn from the current, Voltage, V = P/I
Hence the battery Voltage should be, V = 500/10 = 50Volts or little higher.

Now the Capacity can be in terms of KWh, (500*3)/1000 = 1.5KWh (Considering 3 hours of load to be extracted from battery)

Ques.5
The starter & the ignition switch are connected in parallel to the battery. because both have high load demands at time and hence the equal potential difference on both of them supports this situation.

Ques.6
Ammeter & battery are connected in series. Because generally the ammeter works in series with battery to measure the current drawn from it, it has very low resistance and has very less impact on the voltage drop.