I have been using only the mini key for my vehicle for 2 1/4 years. Now I have repeated a message in the control display that the battery level is low, and I have to pull the door handle repeatedly or step very close until the vehicle opens. I mean the Volvo actually stated the lifetime at three years, but just can’t find the info. A spare key costs around 200 € and my dealer refuses to use the W guess now I actually have to use the regular key for the last few months, which I find unbelievably impractical. Does anyone have any experience about this? — Instructions can be found in the FAQ: https://www.motor-talk.de/faq/volvo-xc90-2-v90-2-q204.html?… Short version: I changed the battery of the Key Tag with approx. 20 Euro, everything works perfectly. Volvo calculates for an exchange 220 Euro. If you can solder yourself, you can push the cost to 5 Euro for the replacement battery.