The yellow warning light indicates a problem with the 12V battery.

[Rashman4u]

My automobile has been rather idle for the last several weeks. The vehicle in question is a 2019 E220 diesel model. The aforementioned notice has been shown on the dashboard both today and yesterday. I plan to operate the vehicle later this evening, since I was unable to do so earlier. Interestingly, on the distinct battery and engine menu, it seems that the battery is well charged and the notification vanishes after about one minute. Will the battery remain functional till I reach an automotive repair facility next week? Tomorrow, I will be embarking on a journey that will need me to spend a duration of 2 hours driving. Can you provide me with your assessment on the feasibility and safety of this endeavour? The battery remains unchanged so far.

[bvlenci]

An amber light often indicates that the automobile may still be driven, but it is necessary to seek help. A red warning light indicates that the automobile is not safe to be used.

The starting battery is most prone to causing difficulties while attempting to initiate the engine. While operating the vehicle, the alternator will provide the necessary electrical power, rendering a weak starting battery inconsequential once the engine is in operation.

[Rashman4u]

Thank you, bvlenci . During transportation, the current measurement has reached 14.8 volts. There is no message shown on the dashboard. I will schedule an appointment for a check-up next week.

[spiezen]

It is likely that your two-hour journey today will sufficiently recharge your battery to a satisfactory level.

If you have a friend who is knowledgeable about cars, they could charge the vehicle for a few hours to fully recharge the battery. However, I would not recommend visiting the mechanic until the yellow light returns after your lengthy trip.

[bvlenci]

When the vehicle is in motion, the voltage you see is not from the battery, but rather from the power produced by the alternator.

Moreover, a voltage of 14+ Volts produced by the alternator indicates that the battery's current charge level is less than 80%. When the battery reaches 80% capacity, the Battery Management System (BMS) will lower the charging voltage to 13+ Volts. This is done to slow down the charging process and increase the lifespan of the battery.

[Rashman4u]

I have recently travelled a distance of over 100 km by car. The battery is indicating a voltage of 14.2 while in transit. Occasionally decreasing to 13.8. Did not exceed such thresholds. The warning light only illuminates after the vehicle has been parked for a period of time. Currently, there is no indication or alert about the reading of 14 following the ignition process. Require durability throughout the duration of the weekend, including during transportation on a boat. Intend to use a physical key instead of an automated system.

[clk320x4]

The voltage of the alternator will remain consistent as long as the engine is operating, as previously mentioned in this discussion.
A high-quality battery normally operates at a voltage of around 12.8 V. It is important to note that the battery voltage never exceeds this value. Therefore, the voltage output of your alternator would range between 13.8 V and 14.2 V. Regrettably, this does not indicate that your battery is completely charged.

[bvlenci]

A voltage output of 13.8V from the alternator indicates that the battery has achieved a charge level of 80% or above.