The BMW’s power supply and control system are distinct from other battery power management systems in that it is simple and self-contained. The battery safety terminal sensor is part of the battery positive clamp that clamps to the battery post and is mounted at the end of the battery positive cable.
When your car is engaged in an accident, the battery safety terminal is designed to disconnect the battery. It plays an important role in the BMW battery’s overall functionality and safety. When the BST sensor fails, the airbag light illuminates. Once the BST has been ignited, it cannot be used again and must be replaced.
What is a battery safety terminal?
The Battery Safety Terminal (BST) sensor is a safety device designed to limit the possibility of a short circuit in the case of an accident. The BST sensor is fitted to the battery post as part of the battery positive clamp. This safety feature is designed to disconnect the battery in the event of a collision for your and your BMW’s safety. The BST design is a good one because it can help prevent engine fires and save lives. However, even the tiniest impact, like colliding with a curb, could trigger the sensor to unnecessarily disconnect the battery.
Factors that Cause Battery Safety Terminal Failure
- Corrosion: The sulfuric acid inside the battery releases hydrogen gas, which causes corrosion. A corrosive environment forms as the gasses react with the outer air. Salt and moisture, on the other hand, serve to accelerate the process. Battery terminal corrosion usually occurs on the negative battery terminal and is a sign that the vehicle’s battery has been undercharged. Due to the vehicle’s relatively short usage and electrical load demand the alternator doesn’t even have enough time to replenish lost battery capacity, resulting in undercharged batteries. Battery corrosion on the positive battery terminal is a warning sign.
- Accident: The battery safety terminal is most likely to fail after an accident has occurred and is left unchecked, which may in turn cause your BMW to stop working. This is why you should employ the services of professionals at Ultimate Bimmer Service to have it checked and fixed.
- Explosion: When the BST detonates, it pulls the red battery cable away from the terminal, preventing the circuit from being completed. There’s also a piece of plastic that keeps the cable from passing through the connector after the detonation. At this time, secondary power to accessories is still accessible, but the engine and other systems will be turned off.
Symptoms of Battery Safety Terminal Failure
- Your car will not start: One of the first signs of a problem with the battery terminals is difficulty starting your car. If corrosion forms along with the battery terminals, it may disrupt the connection, causing your car to fail to start. Corroded or even loose battery terminals might cause this. When the key is turned, the car may have trouble starting, slow cranking, or quick clicking.
- Electricity failure: Electrical power loss is another common indication of a damaged battery terminal. When a terminal is highly corroded or broken, this happens. A terminal that is significantly corroded or broken and does not make proper electrical contact can result in a complete loss of power. Terminals that have deteriorated to this extent will almost always need to be replaced. Battery terminals play a crucial part in the overall performance of your car’s electrical system, despite being a fairly simple and inexpensive component.
- Battery Corrosion: Visible corrosion is one of the most obvious signs of a battery terminal issue. Because the terminals are in close touch with the battery, they are exposed to the acidic vapors produced by the battery acid, making them prone to corrosion. This can interfere with the battery terminal’s ability to conduct power and in severe cases can even completely block the flow. If there are any symptoms of blue or powdery white corrosion on the terminal or along the wire, a close check will indicate if there is an issue.
We Are Here to Help!
Our skilled specialists at Ultimate Bimmer Service located here in Frisco know exactly what your BMW needs and when it needs it. We keep all routine maintenance on your BMW on track and make sure you are always aware of what your car requires.
This results in more tailored treatment that eliminates costly and needless add-ons, allowing you to get back on the road in a vehicle you can rely on. You can also visit us if you live in or near by Carrolton and Dallas, TX. Contact us today to book an appointment!
* BMW 3 Series Car image credit goes to: D. Lentz.