I think I might have finally figured out what's killing my battery, but I need some confirmation from people who know more than me. I have a 2015 Honda Accord and my battery has been dying every few weeks, especially during hot weather. I've replaced the battery, tested the alternator, and even had a mechanic check for parasitic drains. Nothing obvious was found. But then last week, I noticed something interesting. I was sitting in my car in my parking lot with the engine off but the doors locked, and I heard my car alarm's siren making a very faint, weird buzzing sound. It wasn't loud enough to wake anyone up, but it was definitely making noise. Then I remembered that my car alarm has a backup battery inside the siren unit itself, because the alarm is supposed to work even if someone disconnects the main car battery. I've read that when those internal batteries start failing, they can draw power from the main battery constantly, trying to charge themselves. In the extreme heat of Sharjah summer, those internal batteries can fail faster. I found a website that explained how to prevent car battery issues in heat and it mentioned exactly this problem with aftermarket and even factory alarm systems. Has anyone else experienced their car alarm draining their main battery? How can I test if that's the problem? Is it safe to just disconnect the alarm siren temporarily to see if the battery drain stops? I don't want to disable my security completely, but I need to figure out if this is the cause. If the alarm siren is the problem, do I need to replace the whole siren unit, or can the internal battery be replaced separately? Roughly how much would that cost? I'm not very handy with car electrical systems, but I'm willing to learn or at least know what to tell a mechanic. Please share your experiences if you've had this problem because I'm desperate to finally solve this mystery after months of dead batteries. Any advice would be greatly appreciated.