Action camera stops recording on 18 minutes

I am using Denver ACK-8062W action camera to record while I'm driving my motorcycle and it always stops on 18 minutes, I tried using "loop video" feature where the camera starts a new clip after 5 minutes, but the camera records 3 5 minute video clips and stops on the 4th clip's 3rd minute. It doesn't appear to be a file size limitation, because the 5 minute clips are bigger in size then the 3 minute. It doesn't appear to be a storage limitation, as I had 20 GB of free storage before the recording began. It doesn't appear to be a battery limitation, as I had full battery after the recording had finished. the format file is FAT32 and the camera doesn't overheat. Can anyone help?