When the battery in your BMW won’t hold a charge for longer than a few days, it can be a complicated problem to fix. Fortunately, there are ways to fix a battery discharge in some cases. In other cases, you must remove the battery and replace it!
Many people replace the whole battery when it doesn’t hold its charge. This is not a good idea. Rechargeable batteries have memory. When they are charged, they remember what charging speed they were at when they was discharged. This happens with gel-type and lead-type batteries.
If you remove only the positive (-) terminal of the battery, then no memory happens. This is what makes sense for how to fix a BMW battery discharge. If you take out only the positive (-) terminal of the battery, then no memory happens. This is what makes sense for removal purposes!
When removing a cell’s negative (-) terminal, remember to put it back in correctly so that nothing interferes with its operation.
Stop using your battery until you can fix it
If you notice any of the following symptoms, do not use your battery until they can be fixed:
Widening and rising of the battery’s charge level gauge While driving, the gauge increases and drops When parking, standing up or walking away The charger may turn on as soon as the battery is inserted onto it When this happens, look for a warning sign that says not to charge until you can confirm that the batter is charged.
These symptoms are common when a BMW battery has had a long time without being charged. The lack of use may have stretched the batter’s life even though you might have been careful about when to recharge it.
If you do need to drive your car with a low battery, you must stop using it and take it to a BMW service center immediately. They will replace or repair the battery if needed. They also will advise when you first purchased your car on how long your batteries last after being charged.
Replace your battery
If your car won’t start after thirty minutes of being parked with the headlights off, then it is time to replace the battery. Leaving your car uncharged can result in it developing a slow charge, or a charge and discharge process that results in poor performance.
The best way to fix a battery discharge is to take your car to an electrician and have him or she replace the battery. This is because the electrician can connect the wrong kind of charger on the battery, which will fix the problem.
There are several ways to replace the battery on your BMW, some of which we will cover here. First, you can do this yourself using something called a jumpstarter. These are very popular these days because they are so easy to use.
Then, you can have an electrician do it for you.
Check your alternator
When your car’s battery is down, the alternator may charge up the battery. However, if your car has a low-battery feature, then the alternator does not charge the battery.
To check if your vehicle has this feature, look under the hood and see an orange/yellow wire. This is the charging line that connects to the battery via an external source such as a generator.
Replace your alternator
If your car has a small alternator, you can safely remove it to replace the battery. However, if you have an enormous battery or a small one, then you can safely replace the alternator.
The reason to replace the alternator is that it charges the electric system. The charge time of the alternator is proportional to how much energy the car needs. For example, a car that needs very little power will have an extremely short charge time!
The replacement of the alternator also ensures that your vehicle will be able to charge its own battery when it runs out of power. If you had removed it before, then you would have had to buy and installed when your next trip to BMW repair your car!
To install an old replacement as opposed to a new one, first test that it works by plugging in an electrical appliance (computer mouse etc).
Check all cables for damage
When working on a battery failure, it is important to check all of the cables for damage. These can become exposed when removing the cover on the battery.
Many people break off or damage these by wrapping a loose cable around a hard object, such as an arm or leg. When this happens, the object becomes your focus and you can easily remove it from the cable.
Others just unwind all of the cables until they find the faulty one and then solve their problem that way! It is best to be careful with this method though as you could end up with wire fragments in your hands or on your wiring.
If you need to remove the cover to check cables, use some warm water and a mild dish cloth to clean up any water spills.
Recharge your battery and test again
When you connect your car to a power source, you have to account for the fact that the battery is charged. When you discharge the battery, the charge gets back!
This happens because when power is removed, its charge system kicks in and maintains a charge on the cell. If you leave your car running without this system maintaining a charge, it can lose its strength over time.
To prevent this from happening, connect your car to a charger when it is parked for an hour or so to ensure it has a full charge.
To test if your BMW has a battery discharge, first check the voltage. If it is low, then look under the hood of the vehicle to find an alternator. If one is present, then your battery must be receiving enough power from the alternator to maintain its strength.
If no alternator can be seen, then we recommend checking whether or not there is enough power coming in from the charger. When checking this, we suggest using a simple tester.
Find out what is causing the discharge
When a battery gets too little power to hold its charge, it can send out a small amount of electricity. This is called a battery recharge.
This happens when you turn your car’s engine on, and the fans and lights come on. The same thing happens with your car’s battery!
Unfortunately, the fans and lights may not work as well as they should with such a small amount of electricity. This is why they need to have an outlet nearby to charge their device!
If you have a BMW that has a small antifreeze system behind the trunk, then you have even more of an issue! That must contain enough power for these tiny fan and lighting systems.
Finding out what is causing the discharges can be tricky though.
Clean your terminals and replace batteries if needed
As described in the introduction, a BMW battery can discharge when not being used. This is normal, as your car doesn’t require a battery while it is sitting on the shelf!
When this happens, it is important to check your battery. Sometimes, the charge is too strong and doesn’t last until the next use. Other times, the charge was too low and didn’t last long either.
Either way, it is important to check your battery when it has no engine use or discharges are slow or stop. Many people find this to be an easy way to keep a healthy battery over time.
You can do this by checking both the terminal connections and the overall health of the batteries.