I talked to my Service Advisor this afternoon. She told me that BMW recommends that I use a battery tender if I'm not going to drive my X5 for a few days. I asked her if they would give me one. She told me I would have to purchase one from their parts department. The only other suggestion that she made was that they would check to see if I had some kind of a drain on my system the next time it is in for service. Of course, if it "starts happening more often, bring it in before your next service".

For those that have said that any kind of vehicle left for a while needs a battery tender, I disagree. I think it's simply a matter of not having a large enough storage capacity. Most Diesels that I know of have two batteries. As a matter of fact, the vehicle I drove the other day when this one wouldn't start has been sitting since at least August without being started one single time. It's an Army surplus 1984 Chevrolet K5 Blazer. Diesel powered also. It started after the "wait to start light" was on or about a full minute (using tons of juice for the glow plugs). Then it just started right up, ran rough for a few minutes and took me on my way.