My 1988 mercedes battery keeps draining what could be wrong

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.

Don't you have some warning lights on your dash? MB cars are fly-by-wire that tend to depend so much on battery electricity when shut off. Use a high amps battery or battery recommended matching your car model. Check on some instruments that can be a parasitic drain to your car like, car alarm, sticking relays on auxiliary fans, radios. Worse you have a short somewhere or a wiring harness issue, but it should be giving you a warning on the dash.

A mechanic would disconnect the battery and check for a drain on each circuit in the car.
Could be a bad diode in the alternator, a light on somewhere, a stuck relay, and so on.

right if the fuse blows there should not be any air blowing. Anyway this sounds like your have a bad ground in the circut this is running on. Simply get a meter and check the circut from the battery all the way around ac circut and back to the battery. you will find it as auto electronics are very simple once you put aside your fear of it and realize that it current starts at the battery and ends there. Follow the ac's circut and the problem will be found. good luck

The alternator is unserviceable which doesn't keep the charging system going.When the battery is fully charged the vech will run and drive for a while until it drains the charge down in the battery because it isn't being replaced by the alternator......Hope this helps.

OVP relay, box with fuse by battery is a common cause. Coil by drivers headlight another huge cause as no one replaces these.

Aux heat pump maybe failing. Its on the passenger side by the battery. Follow the hoses. Its moves water to the heater core.

First, make sure to check that the alternator is actually charging the battery. Then connect an ammeter between the battery lead and the battery (either one) and start checking for draw by removing fuses one by one till it goes away.Then go into that system to find the source of the problem. You did make sure that the battery is good?

aftermarket stereo? dome lights? car alarm? Use a multimeter and see what fuse has power draw when car is off.

one of the problems could be , you have a bad drain on battery, check charging system,if you disconect battery and hook it back up does it ark if so check all elecrical components for drain