C180.. Discharging Problem

[jonkil]

Hi all,
New to the group.
I have a C180....1998 model year with 31,000 miles and have an on-going problem with it discharging the battery when left for more than a few days.
Within a week the battery will be totally and utterly flat....... " new batteries have been fitted...... it is charging 100% and the dealer cannot find a substancial drain on the system to cause this concern.... No modifications or any electrical extras have ever been added.... no boot light/ glove box lights comming on.....

Is the Alternator have any known concerns to cause a drain ?
Is there any other known concerns which can cause this ?
I am totally baffeled with it & I am removing the battery lead to stop it draining at the moment.

Many thanks in advance if you can offer assistance.

Jon

 

[spanners]

Battery drain

Remove the negative terminal with the positive still connected and put an electrical test light between the post and the disconnected lead. The amount the test light glows represents how much the battery is being drained.

With the test light glowing, remove each fuse in the fuse box one at a time and hopefully one of the fuses will cause the light to go out. You have then identified the circuit.

I hope that works for you.

 

[benzover]

re battery discharge

normally because the battery is in the boot u can pull the boot light switch plunger out to switch it off therefore no drain showing when tested but when boot closed sometimes the light stays on its a bit like the fridge light does it go out or not throw someone in the boot & shut the lid to check but let them out eh!!

 

[hocky4711]

boot light

I thought this resets back when you close the boot so that when you open it again, the light comes on like before even though you pulled the plastic pin to turn it off before closing the boot door. The only reason for switching off the boot light when the door is open is when its daytime and you don't want to drain the battery. Maybe a daylight sensor would help if someone could instal this in the circuit.