X3 key - How do you keep the key charged?

[Spanky Deluxe]

Hi all,

We got ourselves a 2004 3.0i X3 on the weekend and so far absolutely love it. The one issue is that one of the keys appears to have a dead battery. I tried what richirich suggested to no avail (The other key exhibited the behaviour as described so the method should work for X3's after all if programming's the problem).

What can I do to resurrect the second key? If it gets charged by just using it then should I use the other key to unlock and the dead key to drive until it works? Can dealers charge them up quickly? I'm thinking of going to the local BMW dealership tomorrow anyway to order a part so if they do then I could get that done. Keeping both keys charged shouldn't be much of a problem when they both already have juice since TOH and I will just use one set each.