92 SL300-24 Electrical drain

[Indigo]

Just had new track control arms and finally looking forward to blasting round the country in my 92 SL having planned a few road trips then the car developed a new fault !
When stored in my garage, with doors unlocked so not to activate the alarm, I previously had six weeks before I had to recharge the battery
However it's now reduced to flat in 24 hours,
I noticed that door lights were staying on, so removed fuse 10, but the foot well light stayed on, so removed bulbs
I then removed the large relay unit in the relay box that has something to do with lighting
The battery is still showing a 12.v drain
In a darkened garage I loosened each fuse under the bonnet fuse box but none gave any indication of a spark
I'm now at a loss what could be causing the drain
Has any one got any suggestions ?
Thanks in advance

 

[RichardF]

Connect your meter up to the battery, remove one fuse at a time until you can identify the problem. Don't forget the fuse box in the boot.

Do you know how much current is draining?

(assuming it's not just a duff battery)

 

[Indigo]

Cannot see that I've got a drain through a fused item as I loosened all fuses in the dark and tried to get them to spark,

The clue to me is that the door puddle lights and footwell lights are staying on

When removing fuse ten, the puddle lights go out but footwell lights staying on, presume there's some sort of device that keeps them on for a few seconds after shutting the door, but without a schematic I'm stuck

I've sent Tony a PM to see if he can shine some light

 

[RichardF]

Could be the alternator. Worth hooking a meter up anyway, see how much of a drain you have.
Did you pull the fuses in the boot too?

 

[Indigo]

Yes, I covered the boot fuses, but I believe they operate the roof only

Yes, I had considered the alternator, be a shame if it's died as still charges at 13.8v

 

[RichardF]

The boot fuses also cover C/L, Windows, roll bar, alarm, antenna, boot light.

Alternator diode packs can cause a drain, even though they charge ok. Some cars you can just change the pack. Not sure about MB. If the drain is unfused, it'd be my 1st port of call.

Have you measured the drain?

 

[Indigo]

Thanks Richard
No I haven't measured the drain, but will do, I'm a bit short of time this week but I'll let you know how I get on
Regards

 

[optimusprime]

This is a fault you get when alternator regulator needs replacing... It can and will go flat over night with this problem

 

[Indigo]

Alternator

Thanks OP,
ill measure the voltage leak with the alternator unplugged, and report back

 

[Indigo]

Found the fault !
Turned out it was the electric aerial
The mast was not returning fully, and as long as it was not fully seated seems was drawing a voltage, I simply oiled the mast and hey presto
Now standby draw is 0.05 amp, clock presumably , and after two weeks garaged car still starts on the button.

Thanks for all your help