Electrical gremlin
If you ever have worked with manual start engines, and I'm sure you have, you'll notice they run just fine on the magneto. Same idea.
So to your first question. "What discharges said battery?"
The battery discharges whenever it is connected to a complete circuit AND its the power source with the highest voltage.
So in practical terms.
The battery discharges during starting, recharges after starting, and does pretty much nothing until its time to restart the engine.
Occassionally the battery will help out at idle when the electrical loads exceed what the alternator can provide at 14 Volts.
The battery is at best capable of providing power at 12.8 Volts.
The proof is shown on the ammeter. When you are driving, what does the ammeter show? After the battery is charged, it shows no current flowing in or out.
Now lets look at the current flowing through the ammeter at start.
Its 3 to 5 amps. Just enough to deflect the ammeter a little.
That current goes to the ignition and the starter relay.
The power to the solenoid splits off at the relay.
Power flowing through the starter goes direct through the heavy cable to the starter.
Once the engine has started, the alternator's rotor can get powered up. From that point on, power flows from the alternator to whatever circuits are closed. Some goes to the battery until its recharged. We can measure 14 volts in the power lines because of the alternator.
Power is supplied from the power source with the highest voltage.
On a typical setup the wiring which sees the highest loads is from alternator to the main splice. It carries all of the current to run the things the operator turned on, plus whatever is demanding for recharge. Running the heater fan, headlights, wipers, can add 25 to 30 amps. That current doesn't show up on the ammeter.
Why?
Because its not going through the ammeter.
Bottom line. Once the battery is recharged, no current flows through the ammeter as lon gas the alternator can provide power.
Normal driving, the current flow looks lilke this.
Actually, some people do the equivalepnt of that to test the alternator. They disconnect the battery and if the car keeps running -and often it does, the pronounce the alternator good. Its not actually a good test, and additionally can cause problems, but the point is the battery is not needed once the car is running.
If you ever have worked with manual start engines, and I'm sure you have, you'll notice they run just fine on the magneto. Same idea.
So to your first question. "What discharges said battery?"
The battery discharges whenever it is connected to a complete circuit AND its the power source with the highest voltage.
So in practical terms.
The battery discharges during starting, recharges after starting, and does pretty much nothing until its time to restart the engine.
Occassionally the battery will help out at idle when the electrical loads exceed what the alternator can provide at 14 Volts.
The battery is at best capable of providing power at 12.8 Volts.
The proof is shown on the ammeter. When you are driving, what does the ammeter show? After the battery is charged, it shows no current flowing in or out.
Now lets look at the current flowing through the ammeter at start.
Its 3 to 5 amps. Just enough to deflect the ammeter a little.
That current goes to the ignition and the starter relay.
The power to the solenoid splits off at the relay.
Power flowing through the starter goes direct through the heavy cable to the starter.
Once the engine has started, the alternator's rotor can get powered up. From that point on, power flows from the alternator to whatever circuits are closed. Some goes to the battery until its recharged. We can measure 14 volts in the power lines because of the alternator.
Power is supplied from the power source with the highest voltage.
On a typical setup the wiring which sees the highest loads is from alternator to the main splice. It carries all of the current to run the things the operator turned on, plus whatever is demanding for recharge. Running the heater fan, headlights, wipers, can add 25 to 30 amps. That current doesn't show up on the ammeter.
Why?
Because its not going through the ammeter.
Bottom line. Once the battery is recharged, no current flows through the ammeter as lon gas the alternator can provide power.
Normal driving, the current flow looks lilke this.