The engine not cranking in BMW E38 had been one of the common issues in the cold. If you are wondering what the cause would be, it is the E38 battery charging failure. If your E38 has the same problem, it is usual to think about how to check the E38 BMW battery can not recharge.
Well, there are many ways to check if your E38 is getting recharged or not. But the most convenient way to check the battery’s charging status is to use the onboard diagnostic system of BMW.
No worries if you are not familiar with the method. Explore this article until the end to learn about different techniques to inspect the BMW E38 battery charging status.
How To Check BMW E38 Charging Status?
Checking the battery’s capacity and charging state are the two most important aspects of a car battery inspection.
In the Seven series BMW E38, there are multiple ways to check if the battery of the BMW E38 is not recharging properly.
Here we shall get acquainted with utmost convenient ways to check the battery status.
Voltage Inspection Via High Cluster Method
The E38 model of the BMW is renowned for its versatility and user’s luxurious experience. Many diagnostic electrical features have been added over the years, from 1995 to 2005, to control the vehicle easily.
One of those features is the onboard diagnostic system. It has been embedded within the instrumental panel itself. However, the control methods are primitive compared to present-day vehicles.
To check the battery condition, press and hold the right control button on the instrument cluster. At the same time, turn your key to the first ignition position. An illuminated writing saying “test no 1” will appear on display.
You can use the left control button to select the options. Now activate test number one to see the vehicle’s VIN and add its last five digits to unlock the cluster.
Select test number nineteen using the right button, followed by tapping the sum of the last five digits of VIN to unlock the cluster.
Once unlocked, use the right button to scroll through different tests and select the Battery voltage option. In most E38, the battery voltage test is number nine. Tapping it will display the current-voltage status of the battery.
A healthy battery will show 12.5V and above with the engine and electricals switched off. If your battery has a lower voltage than 12.3V, it requires replacement or servicing.
Battery Testing Using External Device
Many smart car battery testers are available in the marketplace. These come with many integrated features that allow you to easily diagnose and check the battery health of your E38 BMW.
All you need to do is connect the positive and negative terminals of the tester to the battery and turn on the vehicle but avoid cranking the engine.
After that, select SOC to inspect the battery’s idle state of charge (SOC). Moreover, you can test the CCA (Cold Cranking Amp), SOH (State of health), etc.
These tests are followed by the tester’s igniting the engine, using AC, a high beam of light, etc. Therefore you will instantly get an overall report about the battery recharging state.
A negative rating means you must replace or recondition the battery to keep it from failing in ignition.
How To Check The BMW E38 Charging System?
The main component that keeps the battery voltage on track is the alternator. It is a generator that transforms the engine’s mechanical energy into electrical energy using alternating current (AC).
Thus, the battery is discharged using different onboard electrical equipment and recharged automatically while the car runs. Using your onboard diagnostic system on the instrumental panel or a battery tester (multimeter), you can run four tests.
Utilizing the instrumental cluster to run the BMW E38 charging system is recommended, as you can also drive the vehicle while doing the tests.
Battery Charging Test With Engine Off
Put your key in the can and ignite the electricals to go through the battery health status on your instrumental panel. Check if the voltage reading is more than 12.9V. It shows the current SOC (state of charge of the battery.
Now, switch on the high beam for five minutes and record the voltage fluctuation on display. If the charging system is on track, the reading shall not drop below 12.6V
Battery Charging Test With Engine Turned On
At this point, turn over the engine and inspect how much the battery voltage is dropped to supply CCA and at what voltage the battery is idling.
Since the alternator is turned on, the idle battery reading should be above 13.5V-14.5V. Below 13.5V indicates the charging system is failing.
Charging Status Test While Running Electrical Appliances
You can turn on the AC at different speeds, high beams, wipers, etc to check if the voltage is falling way below the optimum limit which is 13-13.5V.
Charging Status Test While Revving Engine
Engine revving activates the alternator, and the battery starts charging at its full potential. While you are driving the vehicle or revving the engine at neutral, the voltage should get as high as 15V.
This indicates a healthy charging system on your BMW E38. A bad charging system would show around 12.8-13.5V only.
If you are to know more about the BMW E38 charging system, you may go through the following questionnaires.
What does charging fault mean for BMW E38?
The charging fault in BMW E38 means the battery is not getting enough charge to recover from usage. It happens mostly when the battery health gets degraded over time, or the vehicle’s alternator fails.
What causes charging system failure on BMW E38?
A bad alternator, battery terminal connecting issues, or degraded battery health causes the charging system to fail. Besides, a faulty wiring harness from between the electricals may also cause charging issues.
How do I know if the E38 BMW charging system is bad?
If your battery SOC is below the optimum limit, your E38 BMW charging system is failing. Moreover, while revving the engine, the input current increases the voltage of a battery up to 14V or more. Getting a secondary reading other than this shows a problematic charging system.
Can you drive a BMW E38 with Check charging?
The BMW E38 has an integrated onboard system testing capability. Therefore you can check the live charging status of your battery while driving the vehicle. All you need is to activate the battery status and inspect the change in voltage of the battery driving the car.
What are the signs that your BMW E38 needs a new battery?
If your engine fails to crank and the electrical appliances don’t work, you need a replacement for the E38 BMW battery. Besides, getting a very Under Voltage reading at idle means, the battery ran out of its life and required reconditioning and replacement.
Battery draining in four-wheelers is a common phenomenon. Cars such as the E38 BMW lose battery health very early due to a massive load from high-end onboard equipment.
Battery health and charging system can easily be inspected using the self-diagnosing system installed in the BMW seven series (E38). Hence you will not need to pay a high labor charge or buy battery testers to check the electrical systems.
But knowing to operate the instrument cluster to test the battery charging system is important. Lastly, we hope reading this article enlightens you to utilize the onboard battery charging system of BMW E38 and helps to make wise decisions. This way, you can track the battery’s health and act accordingly.