How To Fix Dead Battery in BMW

how to fix dead battery in bmw
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Are you driving a BMW which has an old battery?

Here is what can happen if you are driving with an old undiagnosed battery for too long.

The other morning, you woke up and went outside to start your car, but nothing happened. Your iDrive screen remained dark, all of the lights inside remained off as well, and when you tried to turn over the starter engine, nothing came out except silence.

You turned around and saw that there was liquid in your underbody tray from the night before when you had gone through one of those touchless automatic car washes with the underbody spray function.

Now you’re wondering if the liquid caused your battery to die or if it had died earlier but just happened to coincide with going through the car wash on its own accord completely coincidentally! So here is your troubleshooting guide for dead batteries on a BMW as our story began:

Check the parking lights first before doing anything else. See if the dashboard is lit up, those parking lights (the ones in your rear window) are on – is there a check engine light? If everything is fine, then and only then proceed to do a little troubleshooting for the battery.

If your car is still under warranty, know that this needs to be handled by the dealer from whom it was purchased. So go ahead and start by searching online with phrases like “fix dead battery in bmw”

How do I fix dead battery in BMW?

It is recommended that the battery is charged via a jump-start terminal under the hood.

To do that, you need to connect your charge with a red clamp first and then proceed to slow charging the battery.

It can take up to 24 hours to fully charge a dead battery. Do not let the key in the ignition while the battery is charging.

Another option is to disconnect the battery from your car and take it to a charging station (battery charger) in your garage or your house and wait for it to fully charge. The battery charger would show an indicator that the battery is fully charged.

What is draining your BMW battery: Fix Dead Battery in BMW?

Below are the possible reasons for a high battery discharge in a BMW and how you can test them:

Plugged in external devices

BMWs use an alternator, which is a device that recharges the car battery while the car is moving, using the energy generated from the car engine as a power source.

So basically, the car has a way of replenishing itself. But it only works when the engine is running. If you forget to turn off your headlights in your parked car, there will be no source of energy in use, and so you’ll find yourself with nothing but a limited capacity battery when you return to your vehicle to get back on your way! Don’t worry, we all have those moments—it’s okay! You just need someone like us who can help you out and take care of problems like this before they happen so that everything runs smoothly for you any time of day or night!

So if there is a dead battery and you have recharged it, make sure there are no externally connected devices that are consuming the power from the battery.

Plugged in OBD-II scanner

While there may be instances when you need to leave your OBD-II scanner plugged in to investigate an issue you have with your car, it’s probably not a good idea. Some OBD-II scanners draw more power from your car than others – and this is definitely not going to be a big problem while driving, but it can drain the battery pretty quickly when the car is idle if left plugged in. If you find yourself needing to leave an OBD-II scanner plugged in overnight – then you probably don’t need it plugged in overnight!

BMW Intelligent Battery Sensor (IBS)

In modern cars, especially luxury vehicles produced by the likes of BMW, you have probably noticed that there is a little device attached to the battery terminal, which can be easily overlooked when checking your car’s batteries. When asked about it, BMW product specialists tend to say that it’s used in measuring the health state of your vehicle’s battery or even in finding out if your cell phone has reached peak power levels for charging.

What does the battery sensor do?

The IBS contains a plugin for some dashboard software that monitors various battery conditions: voltage, current, temperature, starting current, and something called closed-circuit current. When the car is parked, the IBS wakes up every few seconds, performs the tests, and goes back to sleep so to preserve battery power.

The infamous BMW IBS

As BMW had developed the E60 and E61 models, there were many problems that occurred with the IBS (Instrument Body System), which was a new technology at the time, allowing for more complex and interesting dashboard displays.

Some of these water-sensitive parts turned out to be rather vulnerable to moisture intrusion, which then caused further corrosion issues. In addition to this, later 5 Series cars and 3 Series vehicles also had faulty IBS assemblies – if your IBS is faulty, it could prevent your car from going into sleep mode and cause effects when it comes to your battery running flat!

How do you test if the IBS is faulty?

To test whether the faulty IBS might be responsible if your battery dies, you simply have to remove it from the negative terminal of your battery. To do this, remove the little red wire that goes into this tiny module. There are plenty of videos on the internet demonstrating how to remove an IBS from a BMW battery.

The infamous “hedgehog”

The infamous “Hedgehog”, also known as FSR (or Final Stage Resistor), happens to be the culprit behind battery-draining cases in a wide number of cars. The component gets its name from looking spikey, much like a real-life hedgehog. You can generally find it attached to your car’s HVAC system (Heater, ventilator and air conditioning). This may not mean that you are supposed to experience issues with air cooling or any other HVAC related issue. Though some people report that the fan remains turned on even after they turn off their car engine.

To troubleshoot your FSR, all you have to do is pull out the fuse in the circuit that corresponds to this component and see what happens. To find the fuse box and identify which particular circuit corresponds to your FSR, just look it up online. Once you determine what circuit your FSR is on, all you have to do is pull out the corresponding fuse and see how your vehicle responds or if there are any changes at all when it comes to how it acts.

The telematics control unit (TCU)

Check if you have a telematics control unit (TCU) in your car. This is known to cause the drained battery when it is faulty. Check out what the BMW TCU looks like. If you have a TCU in your car, it is located in the trunk, behind the trimming. Online videos will help you locate the TCU. The following car models may have TCUs:
Step 1 – First, check to see if there’s a black box located directly below your rear-view mirror at eye level that wraps around the door frame and into the passenger cabin.
Step 2 – You may need to remove the plastic cover surrounding the trimming but remove carefully if it has screws or clips attached because they can break easily at this point.

Some cars require you to lift up on their inside trims to reveal a metal plate underneath where it will be easier accessible.

To test if it’s the TCU that is draining too much power from your battery, disconnect the fibre optics connector from the TCU and replace it with a MOST loop bypass adapter. If you do not have a MOST connector adapter handy, you can just leave it connected directly to the fibre optics header or even remove the fibre optics cable completely.

The idea here is to see if permanently keeping the TCU in a reset state will prevent this issue from happening again. But even then, no harm will be done once you reconnect things back as they were previously. However, you might need to manually turn on your amplifier as well again because leaving it permanently disconnected will prevent it from receiving signal and powering up.

The iDrive main computer (navigation)

Two commonly used gadgets that cause dead car batteries overnight are the CCC iDrive from Mercedes and the M-ASK iDrive navigation. To identify which one(s) might be to blame for your sticky situation, you’re going to need to make a bit of trial and error by disconnecting them altogether or turning them off one at a time.

The unknown

If you don’t have the above five electronic modules on your car, there is still hope for you to see if one faulty module is draining your car battery. Check out this extremely useful video for finding a short in a car.

Faulty alternator

A defective alternator charging system can cause a short in the battery and have your engine warning light come on intermittently. These types of issues are rare, but when they do happen, it’s important to try n figure out the cause of battery drain because there could be serious consequences involved with not knowing what is at the root of this issue that could prevent your car from starting altogether or run dangerously low on volts. Try to Google a free issue diagnosis for your make and model car or truck, and if one doesn’t show up in the area, then you may want to pay out of pocket for full diagnostic testing with an auto repair shop before you decide to purchase a new OEM battery as a fix.


If you’re having a problem with your battery, first check out the nine steps provided by BMW on how to troubleshoot issues concerning your battery. If the issue is still unresolved, bring it to the dealer or independently repair shop that specializes in what you need and let them know that you’d like a BMW-recommended technician who properly resolves new issues with your vehicle at a competitive price.

Does a BMW battery need to be reprogrammed?

There are many ways to save money when it comes to buying a new BMW battery. Because batteries need to be registered and coded, you may want to consider buying your battery through a third-party dealer rather than through the dealership itself. This is because dealerships might quote you higher prices for parts or services than what you could find online. You could also ask about third party options so that you can register and code your own battery at home on your own time instead of dealing with an auto shop that may have longer wait times or be too busy.

What are the warning signs of failure?

Learn to deal with challenging circumstances, even if they happen right before your presentation. Never get caught off guard by failing to pick up on signs and warning signals that are sent out, as pinpointing a critical, but overlooked, problem early enough can help you handle the situation more effectively.

For example, if your vehicle’s headlights are beginning to dim annoyingly often, it might be time to change them or have them serviced.

If your engine has been acting up lately – a subject we will cover in-depth below, recognize the signs of an unreliable starter or battery charge, which could cause all kinds of problems for you.

Is it getting hard for you to start your car in cold weather? It could be getting harder for you to start it up because of a dying battery. Also, make sure you jump-start your vehicle when it doesn’t start after a long day instead of waiting days later when you forget about it until it’s too late!

Final Words

When troubleshooting any issue with your automobile, it’s important to know what to look out for so as to make sure you can prepare yourself in the best ways possible. With great maintenance and servicing BMW Battery, your BMW’s battery can far surpass its five-year life span.

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