Originally Posted by Penguin

I had a 1992 Ford Explorer that was used for a year only for less than one-mile round trips to the coffee shop each morning -- not a single battery problem.

I have a 2005 Ford Focus which is used primarily for short trips, typically less than 5 miles -- not a single battery problem, and still on the original battery with 67,000 miles on it.

If BMW cannot match Ford electrical system engineering, perhaps they need to fire a few engineers and hire some from Ford.

Now, some might say, "But gee, BMWs have such a large number of electrical accessories and sophistication that the electrical demand is much greater." Sure... but you have to keep the priorities straight, and the first priority for a vehicle is to start and transport people from point A to point B. And if you can't keep a battery charged with a 250+ HP engine if the trips are less than ten miles, it is time to hire some new engineers.

Since the vehicle system apparently already monitors battery voltage and length of trips, I would expect they could have simply taken the small weight and cost penalty, put on a higher capacity alternator, and programmed the charging system to be more aggressive in charging if it sees a lot of short trips and/or falling battery voltage.

For whatever reason, BMW seems to be very stubborn to admit errors and fix problems like this, and it will likely be around until the next generation X5, when they will fix it with a higher capacity charging system with a more sophisticated charging program.

My guess is that BMW made the charging capacity too low and slow so that they could gain a bit on the MPG test cycles that governments use for rating the vehicles. But that's just a guess. It is also possible that BMW electrical system engineers are incompetent.