What does high battery drain mean on a bmw?
Caleb Butler 
A common question that is raised in BMW forums and blogs is “why does my battery drain while the car is off?”
There are a few reasons why this happens:
1. You may have accidently left your headlights or interior lights on when you turned off the car and they drained the battery. This can happen to any vehicle, not just BMWs. Usually a warning light comes on if the battery is getting too low.
2. You may have an electrical fault such as a faulty alternator or bad wiring that is draining your battery when the car is off and not being used. This can damage other components in your vehicle and will definitely require additional repairs beyond simply replacing the battery itself. Replacing parts such as alternators and batteries early can be costly so it is best to take care of these types of problems before they leave you stranded somewhere or worse, cause further damage. If you do find yourself needing replacement parts due to high drain, we recommend LKQ for quality OEM recycled parts at great prices!
3. Your Start-Stop feature could be malfunctioning. BMWs, like many other vehicles today, have start-stop technology that turns off the engine when you stop for a red light or at long stoplights. This prevents unnecessary idling of your engine and saves fuel but also can put extra strain on your battery if it is malfunctioning. The easiest way to check this is to simply turn off your car completely (DO NOT use the Start Stop feature) and see if your battery drains faster than normal while it’s turned off.
4. There could be an electrical drain somewhere else in your vehicle causing the battery to drain faster than normal while not in use. You should always try checking all of the most obvious causes before spending any money on parts or labor for something that might not even be the root of the problem.
One common issue that people have with start-stop technology is that their car’s battery dies even when they’re not using it. This is usually caused by a faulty alternator or electrical wiring. If you’re experiencing this, it’s best to take your car in for repair to avoid further damage.
