SF Alternator Upgraded Wire Size?

[cobragene]

My EM. Has separate circuit breakers in engine compartment for both fans and one for headlights, which doesn’t run through amp gauge, sounds like I would be better off with a volt meter? I did put a 250A fuse between bat neg. And frame, probably not necessity but haven’t had any issues. I am curious Patrick if that 10 or 12 GA shunt would burn out wouldn’t that be a fire hazard also? I guess a fusible link is safer because it’s short in length?

[patrickt]

Originally Posted by cobragene

I did put a 250A fuse between bat neg. And frame, probably not necessity but haven’t had any issues.

Alright, as a general rule you don't fuse the negative side of the battery. When you are cranking your engine, the initial draw of your starter motor will be several hundred amps. Yes, several hundred amps. But that doesn't last all that long, just long enough make a magic field for the starter to spin with. Now, my particular old school AC Delco starter draws a good 200 amps while cranking, but as the battery gets weaker, your amps will go up while cranking. So, keep that in mind if you blow your fuse. Chances are you won't, but if you do, you now know why.

Originally Posted by cobragene

I am curious Patrick if that 10 or 12 GA shunt would burn out wouldn’t that be a fire hazard also? I guess a fusible link is safer because it’s short in length?

If you burn up a 10 or 12 gauge shunt wire across your alternator there is something seriously wrong, like a bad fault to ground on the alternator to battery line. If that occurs, you want to have some sort of protection between the battery and the fault because the battery will keep pumping out electrons until the firemen come. The alternator stops pumping when the engine stops running. But even with a protection device (fuse, circuit breaker, etc.) between the battery and the ammeter (but after the starter solenoid) a serious fault to ground on the battery to alternator line is a very bad day in the making. FWIW, I have a 50 amp circuit breaker between the battery and ammeter/shunt and nothing between the ammeter/shunt and alternator.

[cobragene]

If you burn up a 10 or 12 gauge shunt wire across your alternator there is something seriously wrong, like a bad fault to ground on the alternator to battery line. If that occurs, you want to have some sort of protection between the battery and the fault because the battery will keep pumping out electrons until the firemen come. The alternator stops pumping when the engine stops running. But even with a protection device (fuse, circuit breaker, etc.) between the battery and the ammeter (but after the starter solenoid) a serious fault to ground on the battery to alternator line is a very bad day in the making. FWIW, I have a 50 amp circuit breaker between the battery and ammeter/shunt and nothing between the ammeter/shunt and alternator.[/quote]

Would you mind drawing a simple schematic of your shunt and fuse?

[patrickt]

[quote=cobragene;1520380]

Would you mind drawing a simple schematic of your shunt and fuse?

Circuit breaker in Yellow, Ammeter in Orange, Shunt Wire in Green.