The 2015 Mercedes Benz B250e has a warning “replace battery” on the key fob. I took out the battery and sure enough, it’s measured 2.99V instead of 3.3V as a new one. Yes, with 2.99V, the car still drives. The battery size is CR2025. I got 10 LICB batteries from Amazon for $6. The battery
After 12 years, the battery on our 2004 Honda Accord LX key fob was dead. The battery part number is CR1616 3V. We need a small Philips head screw driver to remove the cover. Make sure the battery is inserted correctly with + and – side.