2007 Honda Fit
My car key battery keeps dying within two weeks. It takes one of those 1616 size batteries.
I notice that when I take the key out of the ignition after driving a while, the metal part is really hot. Is that normal?
Could the heat be affecting the battery life inside the key?
Unlikely. I expect there’s an internal defect inside the assembly. I recently repaired my usb memory-stick sized mp3 player. Either no sound from the audio jack (connected to earbuds), or if I pushed on it just right, I could hear one of the two channels. Upon disassembly I discovered the audio jack part was surface mounted to the pcb, and the engineer responsible deciding to surface mount the audio jack when they know it is subjected to significant torque that will eventually break the solder joints, that represents a design flaw. I expect your car key assembly either has a sample defect (something wrong with just that one versions) or a design flaw.
When your vehicle is on the move, the solenoid energizes to prevent you from accidentally taking the key out while driving. Naturally, the solenoid heats up, and the heat energy is transferred into the key’s metal shaft. When you pull out the key after your drive, it will feel hot.
How far is the key away from the vehicle when not being driven?