I stored my mercedes for 4 week and the battery is dead it is normal
Yes, it is totally normal for your Mercedes battery to go dead after 4 weeks of non use due to the onboard computers that drain on the battery. I store my Mercedes for up to 5-6 months at a time. The solution is to install a battery tender that plugs into a power outlet in your garage and this will maintain proper charge in the battery and then will shut itself off until the voltage drops below the threshold again , then will kick on and bring the battery up to full charge. Any auto parts store, ie. Napa, Auto Zone, Pep Boys, etc. carries them. Cost is approx. $35-$45 and take the average person 1/2 hour to install.