When the battery gets to about 7.20v, the safe will not open given the correct code. Otherwise, it seems to act pretty normally. Replacing the batter restores proper function. The code is not lost with battery change. Manual states:
• When the battery runs out, the red light will light on together with the green light after input the
correct security code. Then you will need to replace the battery
I did not remember. Pretty good safe. I wouldn't trust it for 30 minutes with a determined junkie, but it might be okay for a while in a mild house fire.