Re: dashcam
This boils down to the size of the SD Card you have chosen to use.
As soon as you have a new dashcam and have driven around for an hour you can review the contents of the card.
By looking at the size of files it creates you can very simply calculate how much footage (in terms of time) the card can store and thus how long before it starts overwriting old files.
For example, I use a 64GB card.
The dashcam is set on loop recording at the highest HD resolution in 3 min chunks.
That results in files of about 300MB being created for each 3 min clip of footage.
So simple math:
64000 MB capacity divided by 300MB chunks = 213 chunks
Each chunk is 3 min of footage so I will get 213 x 3 = 639 mins in total on the card
That's about 10 and a half hours.
So, if I have an accident, I can rest in the knowledge that it will be a full 10.5 hours of driving before that accident footage starts to get overwritten by the loop recording.
So unless I am planning on driving the length of the country in the same day I have nothing to worry about. I can simple keep driving and then at the end of the day when I get home, make a copy of the important footage.
The smaller your SD Card the less time you will have before loop overwriting begins. I suggest getting a decent sized card like the 64GB or alternatively reducing the resolution of the recording so the camera can record more footage on the card.