Anybody know if the battery can be replace on my x5 key and how?

Both my X-3 and M3's key batteries charge themselves in the ignition. They tell you to use each key at least once a year to recharge them. Aren't the X-5's like that too?

I have no problem with my wife's key.

You may have to get the key reset for the vehicle I read somwhere how to do it so i'll check & post. I think you have to put key in ignition & press door unlock 3 times on key..not sure but i'll check

I tried doing that as well but didn't work. I'm pretty sure it's the battery.

I don't know what year your X5 is or if it's even the same but my key stopped working as soon as I left the dealership and went onto the military post. I could drive with it but it wouldn't lock/unlock the doors. Apparently there are certain things that will 'interrupt' the freq the key uses and cause it to stop working. You have to drive for at least 30 seconds (I think) and the key will recharge/reset itself.

Good luck!

If you live near a military base, you could be affected by the military radio signals. Here is the article about the interferences.
http://msnbc.msn.com/id/6663032
Maybe, it's not the battery. Your car should charge the battery every time you drive.

Good luck!

Try this...http://www.x5world.com/key_reprogram.htm

The batteries should not need replacement as they are RECHARGEABLE and the keys that dont work should be put into the ignition key for a while to recharge. The key in the ignition must be in position
1 or 2 which ever turns on the accesories. That is why it is recommended that you use BOTH keys every 3 months or so!