Strange Alarm Behaviour

I've had my Prius for six months and never heard the alarm go off until Tuesday and Wednesday of this week. Both days the car was in the driveway, locked and both key fobs were not being moved or touched.

On Tuesday the alarm went off about five times in a row. Each time after I unlocked the car and locked it again it would go off again within 10 seconds.

On Wednesday the alarm went off twice in a row.

Since then no problems at all.

I've read on here about the 12V battery being low, and I will test it later, however both events on Tuesday and Wednesday had something in common. A pair of very annoying builders were sat in their van taking a long break (as usual) and their van was parked right behind my car. I watched them and they never left their van or caused my car to move.

I would have thought that if the 12V battery was to blame then it would go off randomly. It seems strange to me that both times it went off in a short burst of bad behaviour and the builders were taking a break in their van right next to it.

Are they messing with me in some way or is it just a weird coincidence?

 

Thanks I'll look into that. Seems strange though that it's now been a week and it hasn't gone off again, but those builders haven't been around either.

Andy