2011 Maxima Loses Power and Dies

[NickC2011]

Hi everyone,
This past summer my AC compressor stopped working. I had the compressor and serpentine belt replaced. Within a week of getting the car back, i started to notice that the battery and brake light would flicker intermittently.
I also noticed a whining sound coming from under the hood. Turns out the alternator went bad too, so i also had the battery changed since it was already a couple of years old.

Since then, I've been having continuous unexpected problems. i lose all power, including no gas pedal response. The battery gets completely drained, requires a jump and battery charge to get it going again.

I've had the car looked at and no one can find anything wrong with it. Battery and alternator have been tested, and everything is operating with the optimal voltage spec.

Hoping someone can provide me with some direction.

[VStar650CL]

First thing is, make sure the battery is still good. It only takes three or four deep cycle episodes to wreck a typical flooded battery. Once that's known good, monitor your charging voltage and make sure it's never going below about 13V. If it is, either your new alternator is messing up or the "smart charging" system is malfunctioning. To find out which, disconnect the Battery Current Sensor (BCS, on the ground cable beside the battery). See if the voltage comes up to 14V and stays there. If not the alternator is faulty, if so the BCS is probably faulty. The BCS isn't worth fixing, if that turns out to be the issue then I'll tell you how to permanently disable the smart charge.

[NickC2011]

Thank you for your suggestions and guidance. I confirmed the battery was still good. Disconnecting the BCS did not stop the battery from dropping below 13V.
I am putting my focus back on the alternator.
I also noticed something else, the last week has been very cold in the Midwest. I noticed that when I first start the car (cold start) the serpentine belt will move side to side for about 10 seconds and then appears to stabilize. It only does this when it's cold (below 20 degrees). I can't get this to reproduce if the weather is warmer.

[VStar650CL]

There has to be something loose or a bearing with end play for the belt to move side to side. Is that movement occurring at the alternator, or someplace else?

[NickC2011]

I'm not sure exactly if its the alternator, here is a link to the video. Thoughts?

[VStar650CL]

The lighting on that vid isn't good enough for me to tell much, but it looks like you're pointed more toward the P/S Pump and the Idler Pulley than the alternator. Either way, that chunk-chunk noise doesn't sound very healthy. That might be from a bearing that's on the way out and "catching" as it turns. I think I'd loosen the belt and spin everything attached by hand. You'll usually be able to feel any end play or glitching in your fingers.

[NickC2011]

Do you think it's possible that whatever is going on here could be a contributor to the root issue of the system not charging the battery?

[VStar650CL]

Sure, if it's a bad bearing or clutch in the alternator that's also responsible for the belt to moving around.

[NickC2011]

Just wanted to provide an update...
Turns out the issue was a defective alternator.

Thank you for all your guidance and suggestions.

[VStar650CL]