Need advice on stalling issue after 5 spd swap

[obos]

Car: 1995 240sx 125K on engine

I just finished doing a 5 spd swap on my car, and everything seems relatively OK. My big problem however is that after about 10 minutes, the car starts acting funny and dies. First the radio will start turning on and off like there's a loose connection somewhere. Then the air bag light turns on followed by the CEL. Then all my interior lights dim until they are off and then my engine dies very shortly after. The first time this happened, I could restart the car at all. No power when I inserted the key into the ignition. Popped a fresh battery in and car started up fine and I drove home.

I first thought it was my alternator going bad. Replaced that and bought a new battery, but then it happened again. Had both alternators tested at autozone and both tested good. The autozone guy told me it might be a bad ground. Car was running fine before the swap.

What confuses me is that after about 5 minutes or so, I can start the car up again and runs for like another 5-10 minutes before everything cuts out again. So I don't think the battery is being drained. Any advice or observation would be greatly appreciated.

[NISTECH]

Alt is not charging the battery plain and simple. You need to see if you blew your alt fuse when you shorted your starter wires to the body when you were doing your trans swap because you didnt disconnect the battery when you did the swap.

The battery will gain a static charge as it sits when it off. This is normal. That is why it will restart a short time later and run for a bit.

[95.240AZN378]

does it start to happen after you turn something on or just happens randomly in 10 min...