BMCC 6K recording time limits

Hello. Yesterday I was shooting video with my BMCC 6K FullFrame camera. It was powered with NP-F980 battery connected to SmallRig NP battery adaptor with power cable (12V) and original battery fully charged was inside the camera. I used Samsung SSD T7 as a storage. I was shooting in Constant Bitrate 5:1 4096x2160 25fps. After an 1 hour and 5 min non stop recording camera stopped. After hitting the record button it recorded 3 more minutes and stopped again. Then after pushing the record button camera was recording for a few seconds and stopped (those files are damaged). It was blinking like turnin on and off the screen by itself when I was trying to operate it. After checking external battery I could tell that it was +- 80% charged and internal battery was almost empty.
What is the non stop recordind time limits of the camera (I do not mean the capacity of memory)? What can be the reason of such situation?

If that is the regular T7 and not the Shield, it is not compatible with BM cameras.

I made an experiment: powered my BMCC with DC (it comes with the camera) and it recorded for 3 hours with the same SSD and camera settins. When I tried to record only with Smallrig NP adaptor with connected battery - camera records for 3 seconds and shuts down. That means that the the reason is in this adapter or a wire (both were bought new and it was the first shooting with them). I measured a voltage and it was 11,8-12.0 V.
Maybe somebody had the same problem?

These cameras don't have recording limits.
Your setup is underpowered and the Samsung T7 isn't compatible.

These cameras don't have recording limits.
Your setup is underpowered and the Samsung T7 isn't compatible.

How to power it propertly with remote batteries?