After leaving my 1988 W124 wagon off & "armed" for 6-days, I wasn't able to start the car and had to be jumped.

I have a yellow-top OPTIMA (3-years old) and after re-charging it and letting it sit for 24 HRS, it tested EXCELEENT both on my tester and the local battery shop's tester. The alternator tested excellent as well.

Here are my current measurements with a Fluke meter:

1) Car OFF and Unarmed:
total draw w/all fuses: 0.11-0.12 amps
total draw w/fuse #9 and fuse "C" removed: 0.049 amps
draw of fuse #9 only: 0.045 amps
draw of fuse #C only: 0.018 amps

2) Car OFF and ARMED:
total draw w/all fuses: 0.23-0.25 amps
total draw w/fuse #9 and fuse "C" removed: 0.17-amps
draw of fuse #9 only: 0.045 amps
draw of fuse #C only: 0.017 amps

Fuse "C" controls: Rear roof light; trunk light; rear door locking; central locking system; door lightsl; reading lamps; antenna; seat adjustment

Fuse #9 controls: Diagnostic Term.; Hazards; Clock; Radio; Vanity mirrors; comfort relay; front roof light

The OPTIMA yellow-top rated capacity is 55 Ah and 120-mins. of reserve (25-amp discharge, 80-F, to 10.5 VDC cut-off).

Did I exceed the capacity of the OPTIMA?

Are these measurements/figures abnormal for a 1988 W124 300TE which also has clocks in radio and ham-gear ?

I noticed no lights or other relays on.

Thanks,

:-) neil
1988 360TE AMG
1993 500E

Dear ke6dcj:

The total average current draw should be about 50 mA (milli) without the alarm. 100-150 mA should be the maximum.

Best regards,

Eric

I did some more measurements this morning.

Starting at 12.89VDC, a 0.10VDC drop in 405-minutes, OUCH!

If 6-days has 8,640-mins., & the drop is constant, that would be a total of 2.13-VDC over 6-days, with a final voltage of 10.76 VDC (OUCH!).

At 45ma, I think fuse #9 is excessive?

Agree?

Thanks,
:-) neil

Have you removed the trunk lamp bulb or sat in the trunk to confirm that it is out when the lid is closed? Sometimes the wires break at the hinge area or the trunk lamp was connected wrong after repairs in that area.

Your vehicle should not draw more than 35mA. Based on my extensive electrical experience on 124 cars anything above this mark needs to be pursued.

No lights are on, including the cargo area of the wagon.

Have you seen problems with the N2/4 warning module or the dome light/timeout circuit? (again, no lights left on, but is that an accurate indication)?

:-) neil

I had a similar problem with my 1986 BMW 635csi. It turned out that the glove box light wasn't going out when I closed it.

I don't know if your glove box light is on the same circuit that's drawing heavy current (my 95 E420 doesn't have a glove box - so I'm not even sure if there's a light in there). But check this out as a possibility.

Regards,
troy 1995 E420 70k

Already checked the glove-box light . . .

:-) neil

Sounds like you have a small leak in the plasma manifold to the warp reactor.

__________________
Glen Tokuhara
Beauty & the Beast and the wagon that could!

I had similar problem with my 400E, my battery drain was also more than 200mA, I found out it was my Becker Radio tuner in the trunk, one IC was short, the tuner never turned off even when the headunit was off, the normal drain should be less than 50mA.

__________________
99 BMW 540i 6-speed 110K Km
03 SAAB 9-5 wagon 80K Km
92 400E (Sold) 245K km
Still missing the days with the Benz, it kept me busy.

FWIW, per the W124 Service CD-ROM, the W124 with the factory alarm should not draw more than 80-ma when ARMED, 60-ma when UN-ARMED.

After eliminating all FUSED sources, the MB Factory Alarm (un-fused) was found to draw an extra 90-ma when ARMED. While no specification is listed, I am assuming this is too high.

The other 20ma was found to be a combination of my integrated hands-free cell-phone kit, and an aftermarket one-touch window module.

I would suggest that whenever adding new electronics, one should document the new current draw (off, idle, in-use) at the fuse-box for later troubleshooting.

:-) neil
1988 360TE AMG
1993 500

I usually just start pulling fuses, one at a time, until I track down the offending fuse (with its associated devices) that has the 'leak'.

Chris
'85 300SD

Problem is, the ALARM ciruit (plus others) are NOT on the Fuse block.

:-) neil