Battery drain overnight on a mercedes e320 2003

You have an excessive power drain from some electric component in the car and it is draining the battery power rapidly. That is, assuming you have a sound battery that is holding its charge.

You need to have some tests run to identify the source of the drain and rectify it. You will need to either have Mercedes do this or a competent auto electrician who is familiar with Mercedes systems.

The battery will not last very long if it is being constantly discharged like this due to the excessive power drain.

Furthermore, if the battery is old and on the way out it will not hold its charge for very long even if there is no excessive power drain. When the car is idle and everything is in working order, there are still systems on the car that drain a small amount of power constantly so you still need a sound well charged battery.

Batteries have a service life of 2-5 years. It seems like your battery is in need of replacement. Have it tested, or if it is more than 3 years old, just get a new one.

take the positive and neg cable off then touch the positive cable to the positive pole....if you see a spark theres a wire somewhere grounding out on the frame or on a metal ground somewhere.....

Hello

Best thing to do is check whats using the power. If you can't find it then i suggest taking it to a mechanic. If your have anything left own over night it will diffecntly cause drainage problem.

use an inductive amp clamp on the battery wires

You have a slow drain of power inside the car wiring. It could be a relay sticking closed, a short to ground somewhere, or a component using power when it should be switched off like a courtesy lamp.
The fuses have to be pulled to find the circuit with the drain.

charge battery fully do not jump it turn key on for 30 sec than offf ,car should start

You will burn out your alternator if you keep on doing this.The alternator is not a charger. If you have a dead battery you should always charge it overnight on a charger.To keep the battery fresh all that you have to do is disconnect the terminals.Yes this is normal because the car has clocks and alarms that drain power even when the key is off. If you let the battery set to long while it is drained it will not take a charge.

Do the fans run properly and shut off when cars is off? If not they may be draining the battery. A bad stock antenna could drain battery because of the control module. Also the central locking pump if it keeps running (its supposed to shut off after 30 seconds) but if it fails it will drain the battery.

Disconnect each system 1 by 1 or pull fuses 1 by 1 to find out. I would believe its your neutral safety switch tho. Its on the transmission.

Something is draining the power. You have an open circuit somewhere. The sooner it drains(1-2 hours) the bigger the load, the more heat you should be able to detect from the drain. If it takes a lot longer(like overnight) then it will be a little harder to detect. Try unhooking things one at a time. Your alternator could be working properly when the car is running, then shorting when its off. That would make the drain fast. A light staying on under the hood or in the trunk, or dome light would make it drain slower. Or it could be just a wire shorting to ground.