It will run for 3 to 4 weeks on a single battery....that's evil!
I just realized that I've being doing the same for a long time...when I'm in a car with electric windows (and of course I'm not the driver), I push the button to lift them up 3 times when they are already up...the effect is a sequence of 3 bips that everytime make the driver check all the instruments, and then again, and then again...and it's for free!
(I also realized that is not the smartest thing to do in the traffic....)
