No, it wont. It should last about two years. Your Insight will give you PLENTY of warning when the battery gets low before it no longer functions. It's a CR2032 battery and does not require tools to change - just the manual key to pry apart the housing. Takes less than 30 seconds to replace.
I couldn't find Honda-specific information in our G3 Insight Owners Manual nor online, but Prius owners previously reported 12V battery drain due to the car's transmitter/receiver system constantly communicating with various proximity keys (correct key or not) within the car's range. Toyota addressed this thru a Technical Service Bulletin and a feature that activates "battery-saving mode." Toyota seems more direct in communicating the 'risks' than Honda does, and goes further than Honda by automatically activating fob/car battery-preserving features like the following...
From my 2020 Toyota Corolla owners manual:
- If the electronic key is near the vehicle for longer than necessary, even if the smart key system is not operated, the key battery may become depleted faster than normal.
- To prevent the fob battery and car battery from being discharged while the car is not operated for a long time, the (Toyota) battery-saving function is activated when the key has been left within ~11 ft outside the car for >2 minutes, or if the smart key system has not been been used for >5 days.
- If the smart key system has not been used for >14 days, the doors cannot be unlocked from any door except the driver’s door. In this case, hold the driver’s door handle, or use the wireless remote control or mechanical key to unlock the doors.
- To avoid serious deterioration, do not leave the electronic key within 3 ft of electrical appliances that produce a magnetic field (TVs, PCs, cell phones, cordless phones, battery chargers, table lamps, induction cookers).
Honda doesn't seem to include this battery-saving feature, as I haven't experienced any of the above when I've gone weeks without driving my Insight. I think the closest potential parallel on the Insight (?) might be turning off walk-away lock/unlock - gen3insight.com/threads/walk-away-auto-lock.2766/#post-4712
Another option to keep the key on you but prevent battery drain on both the fob and the 12V battery is using a faraday cage/cover for the key fob. "Usual" application is to prevent the key's signal from being picked up and replicated by hackers, but as shown in this video for a Nissan Leaf, the faraday cover can entirely block the key's signal and enable the fob and 12V battery systems to 'sleep.'