Series X/S controllers battery life

The Series X controllers available now uses the same official battery packs as the Xbox One and Series S controllers.

But then if it;s the wrong battery pack, it shoudn't work with either controller ...the fact it works in one but not the other points to an issue with the second controller

The Xbox One Venom battery pack won't even fit in the Series X controller (or at least not without trimming bits off it)..as the OP can fit the pack with no issue, it suggests it's the right battery pack. Unless Venom have released more than one battery pack for the Series X?

I appreciate the reply. However, some AA's, especially when using 2, have more mAh than the official play and charge kit. Therefore, it would last longer. Though there are two issues. 1. This did not happen on older controllers before the X/S controllers with USB-C were released and 2. that creates the issue of making it not rechargeable while in the controller, requiring me to open them up each time the batteries die, which is not exactly intuitive, especially when there's really no warning on windows. Also, I noticed something today, I'm not sure how accurate the battery indicator is on Windows game bar, but I have had my controller connected all day (while playing games), yet the indicator shows it almost dead, which is very concerning. This would explain why my controller dies quickly after unplugging, since it can't charge itself fully when playing over bluetooth.

I should note that I do in fact feel the vibration when plugging them in, and its a fairly new controller so the port is not obstructed.

I've never had that kind of issue with the controller. I'd usually get five or six hours out of it driving a pair of headphones and chat, which you can't do over BT

Try it with a pair of AAs and see how long it lasts. I always recommend just using rechargeable AAs over battery packs, they're cheaper and super fast to change and just keep a bucket of thrm handy.

Yes, as stated I have updated the controller firmware