Originally Posted by jakesdad

interesting concerns that hit home, since I just experienced a catastrophic computer issue in my 2009 xf. Car was cranking slowly, then no crank so I disconnected and changed the battery. Immediately lost key programming, ended up at dealer on a tow truck, and $3400 later I bought a new kvm, fuse box, 2 new keys and an instrument cluster. Yikes. I am convinced sonething was draining the battery while car sitting, and somehow when i disconnected battery, i blew the whole thing up. Other forum members say they never heard of this, yet there are numerous threads about battery drain as well as hypersensitive procedures for disconnecting, changing, jumping or charging the battery.

Originally Posted by pdupler

Jake, the internet and forums are an interesting thing. Its just like your doctor tells you, "When you have a medical problem, come to see me FIRST and DON'T try to look up your symptoms on the internet." The thousands or millions of patients who've been treated and got better just go about their lives and you never hear anything about their illness. The only people who post on the internet are the tiny minority whose condition defies diagnosis, resists treatment and has become chronic. If you read their posts, you'll make yourself sicker just from hypochondria.

Its the same thing with automotive forums. A few dozen Jaguar owners have their batteries go flat prematurely, post about it and suddenly, everyone on the forum, all couple of hundred of us, are buying battery tenders. Probably 98% of owners have never read an automotive forum, never think about such things, rarely experience any problems and just pay for a new battery without question when they do.

Now, if you regularly leave your car parked for days or weeks at a time, there is some logic to it. Batteries deteriorate faster as the state of charge becomes lower and the longer they are allowed to remain in a discharged state, the less charge they can take when they are recharged. Using a maintainer to keep the batteries topped up can extend the life of the battery a couple of years or more as well as keeping it ready to drive.

I like lotus idea of buying one of those jump starter units to put in the trunk when you're going to park at the airport and don't worry about it. The other benefit is when some damsel in distress has left her lights on, you can be her knight in shining armor. (Eventually I'll find a use for every emoticon.)

Originally Posted by Kaeghl

this sounds more like a dealership ripping you off.