I go thru a battery every 4 to 6 years it seems on my x5. No warning when they fail, and the lights, etc usually work but the car just won’t crank.

I had similar concerns about my 22 year old keys so I bought one OEM BMW key for peace of mind. The BMW/Mini site that gets mentioned a lot on the forums was the cheapest and easiest place. Now I’ve got one new master key and two 20 year old back-up keys to turn the lock if I loose the new one. I worry about the EWS system, as well, but not sure what to do about it other than a full delete which I’m not sure I’m ready for.

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Current
Original owner 2002 E53 X5 4.4i to 4.6i swap
2025 G06 X5 50e
Former
1972 Audi Fox
1986 Saab 900S
1996 BMW Z3
1998 BMW E36 M3 Sedan
2004 BMW E46 M3
2006 Audi A3 Quatro
1993 Mopar 318 Jeep Grand Cherokee
2015 V6 Jeep Grand Cherokee