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1985 380sl - charcoal grey w/lt grey interior
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Discussion Starter #1 (Edited)
all,

so i thought it would be helpful to take a quick photo showing the draw on my battery with the car not started and all interior lights off.

i assume this is a milli amp reading of 7.80mA

is this too much draw on the battery??

william
 

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Dallas, Texas
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To obtain parasitic current draw reading you need to connect your amp meter in series between disconnected negative battery cable and negative battery post. Your meter is in engine compartment. Are your test leads that long?
 

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2008 E350, 2001 E320 Wagon; 2000 S430
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Also, the DMM points to 10A range and the black lead plugged into the 10A connection.
The milliamp range lead connection is on the right side of the meter and the range select shall be DCA 200. Your measurement showing 7.8A.
If you have to ask this, you probably not knowledgeable to use the DMM. Next step will be the damage to the DMM. Whitek M is right to measure current you must connect the DMM between the disconnected battery cable and the disconnected battery pole.
 

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'01-E320 & 02-ST2
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And the kicker to all of this is that if you disconnect the battery to connect the meter, that will release voltage and open any closed relays, often zeroing current draws.

They actually make a meter that clamps onto a lead to measure draw. The one in your picture is not it.

There is also a device you can clamp on the negative post and then the lead bolts to it and you can connect a meter in between it. There's an arm on it you can close to solidify voltage in case you need to start the car and shut it off, then you can connect the meter (alternate circuit) and open the arm, thus running all current draw only through the meter. Obviously the purpose-built meter easier and safer.
 

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'72 350SL, '85 300D, '98 E320, '19 Subaru Outback (sold '14 GLK250)
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all,

so i thought it would be helpful to take a quick photo showing the draw on my battery with the car not started and all interior lights off.

i assume this is a milli amp reading of 7.80mA

is this too much draw on the battery??

william
You don't show where you connected the leads. But as others have said, it is all wrong and the reading means nothing. Even if the meter was properly connected, there is a lot more going on than lights and engine.

I tried to measure the drain on my car and believe me, it is not easy on these cars. And I have several types of meter including a DVM, a clamp on and a fuse tester (see below)

As I said before, unless you have a clamp on meter that can measure very low currents (most can't), you can't really measure current drain easily. Even with those, you need to let car site for 1/2 hr or so until all system quieten down.

You can check individual circuits with testers like these:
Fuse Buddy DMM Adapter for ATC Fuses
Fuse Buddy Tester for ATC Use

You would locate the fuse for a suspect circuit, like the seat adjusters and plug one of these in. If it shows a high current draw, then you have your problem. (should be available at Harbour Freight and similar stores)

But my guess is you just need a battery!

Or at least, a friend who understands how the E320 electrical systems work and who will spend some time showing how to do these tests.
 

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Current 2017 GLE350, 2007 S550, 2002 S430, 1998 ML320 Deceased 74 240D, 92 400E, 97 E420, 13 GLK350
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Battery drain diagnostics. Rest battery drain current (quiesent) should be 60 milliamps. Agree with others, location and setup of multimeter looked wrong.

My '97 E420 does not have this problem, but just completed troubleshooting on my '02 S430. WIS troubleshooting is pretty generic between chasis, even with the 2 battery models.

Looked up Startek website, and got a one day subscription for 20 bucks. Nothing definitive for the S430 on this problem. There is a very cool 'On-board electrical system structure description' for the two battery chassis 164/251, 211/219, 221, 230. This contained some generic troubleshooting tips starting with streetglowers advice to measure "quiescent" (rest) current. This instruction directs that the CD be removed from the Navigator, and the Command unit powered down prior to starting the test. Which, after 35 minutes should be no more than 60 milliamps.

Some other tips from Startek on battery drains:
1) if after 30 minutes the quiesent current is less than 1.6 amps, but above 60 milliamps, it is probably not the CAN bus failing to go to sleep. You have a 2000 E class, don't know if it has a Controller Area Network bus (my E420 does not) Less than 1.6 amps means an independent power consumer problem that can be found by pulling fuses and relays. Also on CAN bus troubleshooting, if a control circuit is good, then the CAN High and Low resistance should be 60 ohms with power first removed. Any isolated circuit should be 120 ohms between high and low CAN bus connections.
2) Quiesecnt current can be observed with a clamp on ammeter (Best Choice as described by others), or in line (like I did). Downside of in-line is that the resynchronization has to be done for windows, doors, steering stops, sunroof and low/hi beams.
3) Alternatively, if a clamp on ammeter is not available, a parallel battery can be hooked up to avoid losing synchronization. (too much trouble in my opinion)

Methodology:
1) Key out of ignition.
2) Ammeter in series with battery.
3) Trunk latch manually closed in second position (with boot open to see ammeter). The S430 has the battery in the trunk, the E420 in under the rear seat, will need to block the door switch.
4) Hood up to access front 2 fuse boxes.
5) Passenger side rear door open to access third fuse box, with latch manually closed and and the door switch blocked in the closed position with a yellow highlighter.
6) All doors locked. (FYI - the driver door cannot be manually locked while open. Nice feature to prevent keys locked in car)
7) Copy fuse chart from owners book for a guide to markup with pens.
8) Get the fuse puller from the spare tire tool kit.
9) Methodically pull fuses and check the ammeter for changes.

I only pulled a max of three at at time (easier to keep track of for reinstallation). My methodology was to start under the hood fuse boxes. Of course, the circuit I was seeking was associated with the fuse box under the rear seat, so it was one of the last fuse series that I pulled.

I pulled three fuses at the same time f61, f62 and f63. Reason for multiple pulls is that the car sometimes responds by resequencing sleep for the CAN bus (increased amps, then step lowered). Since I did not want to wait 5 minutes for each fuse, I pulled them small groups. Once you get an understanding of the fuse chart and boxes, it is possible to restore fuses if you get lost on reinsertion.

When I got to the 61, 62, 63 fuses group, quiescent current dropped from 400 milliamps to fluxuations between 20 and 60 milliamps. Then put back each fuse one at a time until the offending circuit was identified.

Photo below shows in line ammeter measurement.

Good Luck
 

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1985 380sl - charcoal grey w/lt grey interior
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Discussion Starter #7
the leads are connected to the positive stub in the engine compartment and the bolt that is grounded just next to it.

what i don't understand is that i had a similar situation happen with my 1990 porsche 911 last year and this technique was accurate and i was able to read the battery draw?

oh well guess i'll just burn the car....
 

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the leads are connected to the positive stub in the engine compartment and the bolt that is grounded just next to it.

what i don't understand is that i had a similar situation happen with my 1990 porsche 911 last year and this technique was accurate and i was able to read the battery draw?

oh well guess i'll just burn the car....
Method for checking parasitic (quiescent) current draw has not changed since battery was ever put in any car. (1918?)

If you connected your amp meter the way you describe internal fuse has blown. Whatever meter displays now has no meaning. Replace internal fuse, connect meter properly and report current draw. Anything more then 50mA (0.050A) needs investigation.
 
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