Why only one fusible link

[71charger_fan]

As I spend many hours checking my wiring circuit by circuit, it leaves me wondering why only one fusible link. There's a fusible link between the battery and the ammeter but none between the alternator and the bulkhead disconnect.

[green69rt]

I think it's really to protect the battery.   Think about the output capability of the source.  The alternator will only put out its rated amps (or close to it), so if there is a short in the circuits somewhere it won't melt all the wiring because the wiring matches the alternator max output (well, it might do some damage but fuses protect stuff.)   The battery is a different animal, it will put out all the energy stored in it as fast as its allowed, hundreds of amps, maybe a thousand.  It can potentially burst from the heat generated and you don't want that!   So it has a fusible link to guard against that happening.

[Nacho-RT74]

Because the only real source able to feed a big short is the battery. Once the battery is out of the game, the alt would stall when a short appears because all the load would concentrate on the short

( not really to protect the battery, but the rest of circuit FROM the battery power )

Remember most of the car is fuse or breaker protected, but charging and ign systems... and headlights ( just headlights, not parking or cluster ). And of course both wires running to fuse box busses ( batt and acc )

Has being told the headlights got a thermal breaker built into the switch too thought... I can't really tell it by personal experience thought.