In this guide, we go over common BMW charging system problems that trigger the battery light to stay on.

It is important to understand that if your BMW is displaying a red battery light or a charging system error on iDrive the vehicle may shut off unexpectedly when driving. 

When you get a battery malfunction on a BMW pull over and soon as it is safe to do so and switch off all non-essential electrical equipment and unplug any chargers plug in the cigarette outlet and USB ports. Turn off heated seats. Rear window defroster and set the blower fan to a minimum if required. 

Keep in mind that the vehicle may not restart and may need to be towed to an auto mechanic or repair shop. 

Symptoms

BMW battery light

All newer BMWs use various monitoring systems to ensure balanced and efficient charging processes. In case of a problem, the monitoring system will alert the driver with a charging malfunction warning message on the iDrive display.

Additionally, there will be a red battery icon illuminated on the dashboard.

Possible error messages and symptoms include: 

  • Battery light on
  • Charing system malfunction on iDrive
  • Battery not being charger, Stop Carefully. 

Common Problems

BMW battery light on

Most BMW charging system problems are caused by a faulty alternator or weak battery.

To troubleshoot your BMW battery problems, start by checking the charging system to determine if the battery and alternator are functioning properly.

After that, the next step would be to use a BMW All System scanner to read the fault codes via the diagnostic port located under the dashboard on the driver's side. 

Common problems that trigger BMW battery warning light include: 

  • Battery - In most cases, a car battery lasts anywhere from 3 to 5 years. However, maintenance, driving habits and the general condition of a car electrical system can shorten the battery lifespan. Another major influence is the weather, as very low or high temperatures have a significant impact. Lastly, Wet cell or flooded batteries require maintenance, as a certain amount of electrolyte will vent to the atmosphere. 
  • Loose connection - Battery terminals can corrode over time, depending on the conditions. If you notice corrosion buildup on battery posts and clamps, clean them up as soon as you can. Not only that this will extend the life of your car battery, but this will also ensure that it has enough charge. You can scrub off the buildup with a toothbrush and a mixture of baking soda and water.
  • Corrosion - The car electrical system is grounded to the chassis at several points. If this connection is not firm and snug, it can cause a bad ground. Another common problem is corrosion.  This will lead to various electrical issues, with charging problems being one of them. In most cases, a nut that holds the cable attached to the chassis goes loose or corrodes. In addition, check the grounding cables for damage or corrosion.
  • Serpentine Belt - An accessory or a serpentine belt uses engine power to spin the alternator. If this belt breaks, the alternator will not rotate and generate electricity. In addition, the car will lose power steering and air conditioning. Lastly, as a coolant pump will not work, the engine will overheat in a short time. Similar problems are possible if the belt tensioner is weak, as this would cause a loose and slipping serpentine belt.
  • Alternator - When your alternator does not generate the required current, the battery light on the dashboard will come on along with a warning message on iDrive. 

You might be confused as to whether the problem is with the battery or alternator.

To find out what is causing the problem visit an auto parts store to perform a charging system test or use a Charging System Analyser to check the battery and charging system yourself. 

If a charging system analyzer is not available use a voltmeter to check the battery and alternator. 

This simple test procedure will give a good insight into the condition of the battery and the electrical system. 

  • While the engine is off, measure the voltage between the battery terminals. A good battery that holds the charge will give between 12V and 12.5V On the other hand, readings below 11.5V show either a bad battery or the alternator that is not charging sufficiently.
  • Repeat the measuring procedure with the engine turned on and idling. A good alternator will produce between 13.5V and 14.5V. Anything significantly below or above these values is a sign of a charging problem.

Don't ignore the BMW warning light. Do not continue to drive with the battery light on as there is a high risk the vehicle may shut off unexpectedly while dring.

If BMW battery warning light on the dashboard comes on while you're driving and iDrive displays a warning message, the charging system is not working properly. The problem most likely is a bad alternator or battery but the fault may be something other than these two components.