I found this image by doing a search for 'Sentra battery charge circuit', just in case the link stops working...
So, looking at this, the SR alternator is bottom-right. There are a total of 5 connections, Ground (through engine block, so no separate wire), White, on separate lug (the 14v output that charges the battery and supplies power to the car while the engine is running), Yellow/Red to turn on the battery light on the instrument console (lights when battery isn't being charged and car is running), a Black/White wire (I'm guessing, but this line is probably there so the alternator knows what voltage it is currently outputting?), and finally, the line I referred to as the 'Sense' line, the White wire on the connector that has 4 wires on it.
Looking at the drawing, you can see this W wire going up to the fuse box, then to the battery. This line is an input to the alternator so it can tell what the battery voltage is. The obvious question is, if the output of the alternator is going to the battery, then why don't they just feed that back into the alternator to begin with at the factory?
The answer is because of the voltage drop from the wiring harness, if the alternator is putting out 14.5 volts, you may only read 14.3v at the battery, depending on the length and size of cable involved. A longer run may only see 14v at the battery. So, the regulator inside the alternator checks what the battery is seeing, and adjusts the output accordingly to whatever voltage it was designed to charge to.
So, say you hit the kill switch, and power from the battery is cut. The White wire is run to the fuse box, which now has zero volts. Alternator, being stupid, does the math, sees that it's already outputting 14.5 volts, and then burns itself out trying to raise the voltage on a non-existent battery.
So, two answers present themselves. Either cut that white wire at the harness, and run this line to where the battery is, and leave it attached to the positive terminal. For most racing series, you can get by with this, because the car will still shut off and not run when hitting the kill switch, but it does mean that you have an active 12v line going to the engine bay after hitting the kill, and in the event of a crash or other mishap, you've got a 12v line possibly sparking around inside the engine bay.
The second option would be to run that White wire over to the lug that provides the output, so that it will always see voltage while the alternator is running. This means that your battery won't charge quite as high as it did before (guessing 14.2v instead of 14.4), which may not be a big deal. A workaround would be to stick a resistor inline between these two so that the sense line sees a slightly lower voltage, but I don't have an easy way to give a good working value for such a resistor at this point, so save that for another day.