Mercedes Sprinter battery charging malfunction – the red battery warning light is lit or flashing while the engine is running. This indicates that the battery is not being charged.
Often the fault is with the alternator or torn / loose poly V belt. Stop as soon as possible and check the poly V belt.
Another possibility is a faulty battery. Vehicle batteries last for around 4 to 6 years depending on vehicle usage and climate. Frequent short trips with many engine starts tend to shorten the battery lifespan – especially in colder climates.
Check battery connection terminals are secure. Have battery and alternator tested. It’s advised not to continue driving with a faulty battery or alternator and to contact a Mercedes qualified engineer.