IGN UNFUSED - Hot during crank?

[davepl]

So here's my confusion: the aux battery is connected via a relay that is triggered when the IGN UNFUSED terminal is hot.

If it were hot during crank, then the aux battery would be trying to feed the starter through it's 10GA connection, which would not work.

If it were NOT hot during crank, people would not be able to hook their HEI up to it, but I think they do.

So it can't be both, but which is it? How can it possibly work for BOTH scenarios?

[kwmech]

It doesn't feed the starter perse, it feeds to the charging system. Factory set-up? if so should be isolated via the relay. If you have the 10 ga wire direct to the other battery by the relay then yes it will feed somewhat, but the starter is still being fed by the larger battery wire from the primary.

[rpmerf]

I've tested my IGN UNFUSED to be hot during crank.

[franken]

It will be hot as long as the key is in the start or run position. That said, chances are not much current will flow that direction since the starter is pulling ~200A while cranking.
I'd ask why would the starter be fed by any 10AWG connection from an aux battery, or how. The starter is a big motor that turns the engine. There's also a small solenoid bolted to the starter that acts as a switch to turn the starter on and to actuate the starter drive. There is no 10AWG wire feeding the starter or solenoid that I know of.

[dmjlambert]

I wonder what the original factory aux battery relay characteristics were like, if it was a plain relay or a time delay relay and energized after a few seconds (which seems like a good idea to me).