How long do car alarms go off for?
I can say that everything will depend on what kind of battery the car has. I will say this, that listening to the sounds of the car alarm is not very pleasant, but for a long time, it is also tedious, it affects the nerves very much, and at night some will not be able to sleep at all.
I remember there was a "seven", the Russian automobile industry, in the next yard. The alarm system started working during the day, but the owner of the car could not be found. They also thought that he would shut up quickly, but it was not there. The alarm system worked in the evening, but it was quieter, and at night it was almost not audible, but it still worked.
Therefore, if you are lucky, then she can yell for three hours, and if you are not lucky, then she can yell for a day if the battery is new and the owner of the car cannot be found.
Having worked on incomprehensible interference, the car alarm started up and creates noise. The time of this test for the ears of neighbors depends on the power of the car battery. It can scream all night and even all day, if the autonomous power supply, until the battery runs out, if it is not turned off. With a weak battery, it will scream for 3 hours, no more. So, the conclusion: if the owner does not turn off, for sure the whole day and even more will shake the nerves of the neighbors and shout the alarm system until its very powerful battery runs out.
It happens that the battery is discharged quite quickly, then the alarm will "scream" for no more than a couple of hours. But it happens that the alarm system works for a very long time. Once we had someone's car under the balcony and as the alarm went off, it worked for half a day. Until the owner returned from work.