Simply put it this way... u have 2 electrical sources in your car. 1 the alternator, 2nd the battery. the alternator has coils in it which produce electric current (charges) when a field is created. how the field is created? the pulley of the alternator is connected via a belt to the main engine pulley rotor. thus when the car engine is running, your alternator is producing current charge.
the battery is also a secondary source of current that will provide current to most of the essential instruments in your car when the engine is not running. however ur battery is in a constant charging cycle via the help of ur alternator. thats why sometimes ur battery is drained when u use most of ur electricals when the car is not running.
hope this clears it.
NOW remember i said the battery is charged via ur alternator. this is where ur big3 comes into action.
BIG3 = Ensuring you have the maximum current flow from the alternator to your battery to your ICE or whatever u intend on running via ur car electrical system
HOW = Using a Bigger guage/awg wire (ie 0 and 2 are mostly used). u connect ur battery's + to the alternator +, the batterys - to the chassis and the engine block to chassis. this ensures maximum current flow. better still, use maximum guage wiring for ur amps too.
