It’s much harder to understand something that’s invisible, so people use something like the flow of a liquid to explain the flow of electricity. Rather than just explain in theory, here I’ll use a practical example - trying to understand poor performance under full load.
The first sentence in each paragraph below talks about the flow of fuel from the
tank with internal pump to the engine after a turbocharger has been added. The second sentence in each talks about the electrical equivalent where electricity flows from the battery to an upgraded compressor in the rear.
a) The problem is that the engine hesitates under full load, so should you upgrade the pump, or is something else causing the problem - some measurements will help you decide.
b) The problem is that the compressor slows down under full load - should you upgrade the battery, or is something else causing the problem - some measurements will help you decide.
a) When the engine is off, the pressure at the fueltank is 12.7 psi and the pressure at the engine is 12.7 psi.
b) When the compressor is off, the voltage at the battery is 12.7 volts and the voltage at the compressor is 12.7 volts.
a) When the engine is at idle, the pressure at the fueltank is 12.6 psi and the pressure at the engine is 12.1 psi. There is a 0.5 psi drop across the fuel line when there is a flow of 1 litre-per-hour.
b) When the compressor has no load, the voltage at the battery is 12.6 volts and the voltage at the engine is 12.1 volts. There is a 0.5 volt drop across the cable when there is a flow of 1 amp.
a) When the engine is at full load, the pressure at the fueltank is 12.2 psi and the pressure at the engine is 10.2 psi. There is a 2.0 psi pressure-drop across the fuel line when there is a flow of 4 litre-per-hour.
b) When the compressor is at full load, the voltage at the battery is 12.2 volts and the voltage at the compressor is 10.2 volts. There is a 2.0 volt drop across the fuel line when there is a flow of 4 amps.
a) Obviously the pump can supply 4 litres-per-hour, but the fuel line is too small and is causing too much pressure drop at the needed flow rate.
b) Obviously the battery can supply 4 amps, but the wire is too small and is causing too much voltage drop at the needed current.
a) How long will the 80 litre fueltank last at full load ? At 4 litre-per-hour it will last 20 hours (80/4).
b) How long will the 80 amphour battery last at full load ? At 4 amps it will last 20 hours (80/4).
a) How many days will the 80 litre fueltank last if I run the engine at full load for 5 hours a day ? At 4 litre-per-hour it will last 4 days (80/4/5).
b) How many days will the 80 amphour battery last if I run the compressor at full load for 5 hours a day ? At 4 amps it will last 4 days (80/4/5).
a) Since it is not a hydraulic power system. no-one calculates the power in moving the fuel
b) The power the compressor draws at full load from the battery is 48.8 watts (12.2 x 4) and the compressor is using 40.8 watts (10.2 x 4) - 8 watts is lost in the cable as heat.