Alternator question

[Red1968]

I have a 69 blazer and when I bought it the original alternator was no good. I had it tested at oreillys and it tested bad. I bought a new one for it but now when I take the positive battery cable off the battery the motor still goes dead like the alternator is not charging. I took the new one back and had them test it and it tested fine. What would be making it do this because I know it is suppose to stay running when you remove the battery cable. I checked all the wires and they were all connected good everywhere. I'm wondering if it is hooked up correct. It has the newer style alternator so it does not have the external voltage regulator anymore. There is a red wire going from the stud on the alternator and it spits and goes to both the positive side of the battery and the fuse box. The red wire from the 2 prong plug on the alternator is also going to the stud on the alternator also and the white wire from the 2 prong plug is not hooked to anything. Is that white wire suppose to be hooked to something, will that wire make it not run with the battery unhooked? I am puzzled with this so any help would be appreciated.
Posted via Mobile Device