I am planning a vacation and was wondering if anyone has kept Sentry Mode on for a long time (8 days). How much extra battery drain would you expect ?
The car will be plugged in my driveway.
If the car is plugged in, you won't have any drain, as it will top off as needed.
It will likely use up to 1-2 miles per hour -- so, about 10-15%/day of 24/7 running, but the car will trigger a recharge when it drops down by about 3% (or at the next scheduled time after reaching that point).
And your bigger problem would be drive space, since you wouldn't be able to clear out the drive if it fills up. This would only be an issue if something is regularly activating it, triggering it to save the recordings.