battery dies in 3 days
 

i have a '94 SL 500 22,000 miles that has a continuos 300 milliamp draw on the battery, resulting in a dead battery in 3 days. I have removed all fuses under hood and trunk, plus removed all courtesy light, viewed the car in the dark and still have the same 300 miliamp draw. Any ideas?



'94 SL500 22,000
'91 560 SEL 88,000
'87 560 SEl 134,000
'86 300SDL 202,000

Somewhere there may be a dead short where current is slowly making contact across a bad connection positive to negative--my guess is in wiring somewhere. Not sure if the S-Class vehicles were involved in the factory main wiring harnesses fiasco of falling apart insulation which caused things like shorts. The problems with the harness were definitely during your year, though. The other idea I had is the CD-Changer. Of course, if you disconnect all fuses, the changer should have no power. Check to make sure it doesn't have independent power to it anyway. On my Range Rover the battery will also be dead in 3 days due to the CD-Changer "remembering" the position of the disc.

maybe?
 

had the same problem with another car of mine several years back. turns out the positive battery cable was at fault, wear on insulation grounded out to a bracket. even though the cable looked pretty good it was drawing out enough to drain battery within a few days of non-use.

Whay type of after-market gadgetry do you have?

Alarm, sound system, big amp for sound system?

Even with a 300 mA draw the battery should last for more than 3 days. I would guess with that load it should last over a week (if decently charged). How do you know that is the current draw?

How old is the battery? I am guessing you might just have an old battery ready for the grave, or the drain current is much larger than you think. Causes listed below are good candidates for that.

Mike

installed a priority start, no longer care where the problem is, problem solved

I am having this same exact problem and am trying to figure it out. With your priority start I would think that your battery would continue to be drained and recharged every time you start and use it, wouldnt that make the battery only have a limited life? I would rather fix this where I did not need an aftermarket device.

It is a 96 SL500.

Spinedoc,

Did you not quit MB and buy a Lexus?

Wow, I sold my 300E and bought an ES300 almost 3 years ago, and almost 2 years ago bought my SL500. Can a user "quit" a forum? Odd.

I had a similar problem
 

I had a similar problem with my 82 380SEL Mercedes......My problem and yours probably arent related however I noticed my car would not start after about three days of sitting idle. My car also had a viper anti theft system connected to the electrical system.......Turned out that this anti theft system was the culprit.....I disconnected all leads going to the viper box and problem was solved. I dunno if it was simply connected wrong or what, but anyway this fixed my problem.