LEGRIA HF R66 only records for 45+ minutes and then shuts down

[Whitesjm]

I have a Canon Legria HF R66, with two large batteries (300min+) and a 64gb card. However, with the battery fully charged and the card empty, the camera shuts down after 40+ minutes. It has now done this twice. Am I missing a setting or is my camera defective?  

[rs-eos]

45 minutes at the highest bitrate (35 Mbps) should only lead to under 12 GB of data.

Are you using Canon brand batteries or third party?  For your SD card, is it full-sized or micro?  And, what specific brand and specifications?

As a test, connect the camcorder to its power adapter and then record.  Are you able to get past the 45 minute mark?  That would then mean an issue when using the batteries.

The only auto power off setting I see in the User Manual is where the camcorder will shut off after a period of 3 minutes of no activity.  See page 55.