Burned bulk head connection
This might be information overload, but the damaged connection at P would be a cause high voltage alternator output.
As current flows through resistance, voltage drops.
If the connection causes 0.1 Ohms resistance and there is 4 amps flowing through it, that's 0.4 Volts lost.
That would be tolerable.
But if the current is higher, or the connection gets worse, it can be a problem for correct regulation.
When voltage is lost on the way to the regulator, the regulator drives the alternator to bring the regulator input into the target range.
Lets say connection a cavity P had 0.1 Ohms resistance and every other connection and wire has no resistance (ideal).
Using the example of an engine running and battery recharging at a moderately high rate:
12 amps x 0.1 Ohms = 1.2 Volts
If we measured voltage to ground at various locations, we'd see the regulator input still at 14 Volts, but the alternator output at 15.2 Volts.
Power is volts times current.
1.2 Volts x 12 amps = 14.4 Watts. That is 14.4 Watts of heat.
This might be information overload, but the damaged connection at P would be a cause high voltage alternator output.
As current flows through resistance, voltage drops.
If the connection causes 0.1 Ohms resistance and there is 4 amps flowing through it, that's 0.4 Volts lost.
That would be tolerable.
But if the current is higher, or the connection gets worse, it can be a problem for correct regulation.
When voltage is lost on the way to the regulator, the regulator drives the alternator to bring the regulator input into the target range.
Lets say connection a cavity P had 0.1 Ohms resistance and every other connection and wire has no resistance (ideal).
Using the example of an engine running and battery recharging at a moderately high rate:
12 amps x 0.1 Ohms = 1.2 Volts
If we measured voltage to ground at various locations, we'd see the regulator input still at 14 Volts, but the alternator output at 15.2 Volts.
Power is volts times current.
1.2 Volts x 12 amps = 14.4 Watts. That is 14.4 Watts of heat.
