How long should a smart key battery last?

• Daily use, fob in pocket near key signals: 1.5-2.5 years
• Hung on a hook at home most of the time: 2-4 years
• Cold-weather use (winter): shorter — lithium chemistry slows below 0°C

Signs the battery is dying

• Need to be closer to the car to unlock
• Intermittent unlock button presses fail
• Dashboard light “key battery low” (BMW, Mercedes, Lexus do this)
• Push-start requires holding fob against start button

How to replace

1. Find the small slot or button to open the case (usually next to the key ring)
2. Note the orientation of the old CR2032 (positive side up usually)
3. Pop out old battery
4. Wipe both contacts and new battery with dry cloth
5. Insert new CR2032 same orientation
6. Close case

Total time: 30 seconds. Cost: $3-5 at any pharmacy.

Extending battery life

• Don’t store in extreme heat or cold
• Avoid pressing buttons repeatedly to “find” the car
• Use the mechanical key in winter when battery is weak (saves charge)