You will never get an exact figure. Not only does it depend on which dash camera people are running but, it could be multiple. Couple that with how often the camera is recording from standby mode to the parking function. The amount of activity or lack there of in front of the camera(s) will surely give you inaccuracies eveytime.
Seriously? It's pretty straightfoward to measure. Drain the battery fully and then time how long it takes to get back to 100%. Easy to do when bench testing at home in your living room. In your car you can also measure over a period of time, logging battery levels at the start and end of your drives and looking at the average and the variance of the results.
Will there be variables such as what dashcam you're running, how much power draw there is, the ambient temperature, age of the battery, and so on? Of course. That's why having even more datapoints is useful. It helps us avoid any issues that could be drawn from using a smaller size data sample and gives us a better picture of what people are experiencing in practice. Not only will we get a variety of numbers, but we can measure things like how consistent people's results are, how much of an improvement there may be when running different dashcams or settings, and so on. There's a lot we can learn and conclusions we can draw, even if the numbers don't match exactly. I know you mean well, but instead of making excuses and arguing why it can't be done, let's get some actual data and take a closer look at it to see what we can all learn together.
This is the last time I'm going to ask to hold off on these sorts of posts for the time being or to take the discussion elsewhere.
