No, Once the alternator starts charging, it will keep the engine running even though the battery is disconnected.
Some guys like to run one huge wire from the battery up front with the disconnect inline, and a second, say, no6 or no4 from the alternator direct to the battery
This scheme would allow the engine to die, but then you still have a big wire hot, from the battery clear up to the alternator.
This is the same scenario that I try to get guys "not" to do, the alleged wives tale of "testing the alternator." The premise is, you remove the battery cable, and if the engine keeps running, the alternator is OK.
That is what happens if all you do is break the battery connection.
