For me it lasted close to 4 years. I had installed a tracker that uses a SIM that you have to keep topped up to receive the messages. No issues where I live so over time I stopped and didn't even think about it. Fast forward, I went through 3 batteries, couple mechanics, bought a portable jumper and a physical battery disconnector and even got a voltage meter and was mucking around with the fuse box etc and just grew to live with it until one day I was cleaning the car, saw the thing and just disconnected it and then a few weeks later I noticed that leaving the car on weekends the battery was fine the Monday (usually had to jumpstart as it would drain). Turns out the tracker was trying to send messages almost every minute THAT it couldn't send messages! So it had been doing that for years and was the tiny leech on the battery, not large enough to be detected but enough to slowly drain a brand new battery over the course of a few days.