Battery Drain Question (Solved)

[Blue Shadow]

Voltage does not test current drain. 

put an ammeter between negative battery terminal and car chassis as the only path for electricity to complete the circuit.  The amperage should be small as stated 50ma or so. Now open the glove box and with the meter still in position you will see a jump in the number cause that light bulb might draw a hundred or two milliamperes. But this assumes your glove box light was off with box shut and turns on, works when the box is open. That bulb will drain a battery. 

I don’t rock at the sewing machine, but I have one and can use it.  I do every half dozen years.  

 

[Mike W.]

Ah, hang on, let me clarify.  I see a .15V difference between the battery in the car, terminals connected, with everything off and the battery out of the car with nothing connected.  I don't know if a .15V difference in this example means anything.  But in my brain this is how you test for a possible parasitic loss.   How am I doing?..please tell me I suck at electrical stuff.  Thats ok.. But hey. I totally rock a sewing machine

How are you doing? You suck at electrical stuff. Comparing in and out of circuit battery voltage test is not a test I've heard of, let alone used. You could theoretically extrapolate some info from it with a ton of extra background info, but in the real world it means nothing.

You need to test for ma draw. That's milliamps, thousands of an amp. You measure that on the mA setting on the meter. To do that, remove the negative terminal on the battery. You probably have a DMM meter with a 200mA on it. Use that one. With everything off of course, connect the meter leads between the negative terminal on the battery and the negative battery cable. It will probably spike up at first, then settle down some. I like to see under 10. Under 20 isn't bad. Under 30 I'm starting to wonder. New cars spec under 50, but that's a lot.

DO NOT CONNECT THE METER BETWEEN THE POSITIVE AND NEGATIVE TERMINALS on a Ma or even any current setting. If you do, at best you will see sparks, quite possibly kill the meter and possibly even blow it up.

[Philo]

Hi Mike, doing fine but agree, I SUCK at electrical stuff big time !

As Blue Shadow mentioned the glove box light might be the culprit in my case.  I've been running without a glove box door for a couple years now because I had to take my S54 ECU out a bunch of times for trouble shooting and it's just plain easier to do it with the door off.    I'll do your test and check the glove box light switch first.  I still don't understand the concept of measuring milliamps off the negative terminal.  I'll start watching some youtube content to see if I can get smart on this shit.    Thx Mike & Blue for chiming in.. 

[Blue Shadow]

To measure current, amperage, milliamperes all the electricity must go through the meter. It will not if there is another path. That is why I picked neg, one connection to break and put the meter there. This for whole car current drain when car is off. 

when testing individual circuits, you pull the fuse as all electricity on the circuit goes through that fuse. Connect ammeter to the two fuse clips. This is the way to narrow down the excess current draw. 

 

[Philo]

This is what I see on the multi meter, not sure if I have meter setup properly though.  The lead when in the mA hole didn't yield a value,  so I switched to A and I got a value.  See pic.

https://www.dropbox.com/scl/fi/17uf8n873jcyjfp51yws6/20250609_182628.jpg?rlkey=0i363zucmf5tojs3g01hlz9ko&st=3szw9vvo&dl=0

[///M]

If you look at the meter there are two fuses on the amp and milliamp settings. On the milliamp it is 400 milliamp and the other is 10amp.  Check the manual you may have blown the fuse on the milliamp side hence no reading. The reading on the meter is showing 21 milliamps
That is a very nice high end meter to have

[Blue Shadow]

Agreed.  Not getting a reading when in mA setting and trying to measure mA means a blown fuse in the meter most of the time. 

[vinceg101]

This is a very salient discussion. Chasing down a constant electrical vampire in the M535i for a long time now.  I have a parallel hot running engine issue (at least that is the obvious observation) which is looking like it might be a cluster ground issue (instead or as well) which is affecting the temp gauge.
I'm going to put these tests, well, to the test.

[stuartinmn]

This is a very salient discussion. Chasing down a constant electrical vampire in the M535i for a long time now.  I have a parallel hot running engine issue (at least that is the obvious observation) which is looking like it might be a cluster ground issue (instead or as well) which is affecting the temp gauge.
I'm going to put these tests, well, to the test.

I don't like veering the discussion off topic, but what are the symptoms of your temp gauge problem?  I've had a thing for a couple years now where my temp gauge works intermittently, and I've found if I pound the top of the dash above the instrument cluster it will usually spring back into action.   This tells me there is a loose electrical connection to the cluster, but when I've pulled it out and inspected it I wasn't able to find anything wrong.  I've been thinking about adding a wire that's a direct connection to the chassis to see if it's a bad ground but haven't done it yet.  So, I'm interested in what you find and if you can solve your problem.

[Mike W.]

This is a very salient discussion. Chasing down a constant electrical vampire in the M535i for a long time now.  I have a parallel hot running engine issue (at least that is the obvious observation) which is looking like it might be a cluster ground issue (instead or as well) which is affecting the temp gauge.
I'm going to put these tests, well, to the test.

I don't like veering the discussion off topic, but what are the symptoms of your temp gauge problem?  I've had a thing for a couple years now where my temp gauge works intermittently, and I've found if I pound the top of the dash above the instrument cluster it will usually spring back into action.   This tells me there is a loose electrical connection to the cluster, but when I've pulled it out and inspected it I wasn't able to find anything wrong.  I've been thinking about adding a wire that's a direct connection to the chassis to see if it's a bad ground but haven't done it yet.  So, I'm interested in what you find and if you can solve your problem.

I never had that problem on my E28, but did on an E3, E12 and early E24. A bad ground, on them fixed by an additional engine/chassis ground, seemed to cure it. On the E24 in particular, even turning on the dash lights would cause a little bump in the temp gauge.

[Philo]

Thx guys, so 21 mAmps is acceptable from the posts upthread.  Regarding the fuse., when I had the test lead plugged into the 400 mA hole I got a test lead warning.  I though that meant that I needed to swap the leads at the battery's Neg terminal and chassis ground.  Anyway, time to buy some fuses to keep on hand because I suck at this and no doubt I blow more in the future  

Also let me mention, about three months ago I swapped the alternator because the radio kept shutting down every time I hit the brakes.  And sometimes when turning on the headlights.  Since this is an S54 I read up on the NAM3Forum board and everyone said to change the alternator and the battery.  I did the alternator, but not the battery.  Fast forward to last week, the battery finally gave up the ghost.  I just failed to connect the dots and thought it was a parasitic drain.   

Anyway, learned a bunch,  Thx for the help !

Philo.

[vinceg101]

I don't like veering the discussion off topic, but what are the symptoms of your temp gauge problem?  I've had a thing for a couple years now where my temp gauge works intermittently, and I've found if I pound the top of the dash above the instrument cluster it will usually spring back into action.   This tells me there is a loose electrical connection to the cluster, but when I've pulled it out and inspected it I wasn't able to find anything wrong.  I've been thinking about adding a wire that's a direct connection to the chassis to see if it's a bad ground but haven't done it yet.  So, I'm interested in what you find and if you can solve your problem.

I never had that problem on my E28, but did on an E3, E12 and early E24. A bad ground, on them fixed by an additional engine/chassis ground, seemed to cure it. On the E24 in particular, even turning on the dash lights would cause a little bump in the temp gauge.

This is/are some of the exact symptoms. While I haven't been driving it much over the last 9 months, I have had it on the road enough for short and long trips to get some kind of 'average' observational experience.

First the apparent engine temp issue:
The primary symptom pointed to a hotter running engine temp than normal (e.g. temp gauge climbs to half even in the coldest ambient temps, say November at 5:30am when it's in the low '50's) and will rise to 5/8" when idling at a light. Yes it will come down when moving again, but not as low as one would expect, even at freeway speeds. This happened kind of all of the sudden one morning and led me down the path of believing I have some kind cooling system issue (which I haven't entirely ruled out) like an errant air bubble since it never behaved like this before. But I have bled the system (many methods) at least 3 times now with no change. In all this time the temp gauge has been acting kind of erratically (rising, falling, some quick up-downs) and then will level off and behave. [Before you ask: No, I have not checked the actual running engine temp with an IR gun, but I'm not sure exactly where the best location is to take that reading.]

Cluster/Dash Ground issue:
So as the last line stated, my suspicions are rising on the accuracy of the temp gauge and maybe there being a grounding issue. Lately I have witnessed the temp gauge 'pulsing' when I activate the turn signal (not all the time but more than before). Other grounding issues are this persistent electrical drain (possibly related but more likely some other electrical connection). Also, I do get an alternator whine coming through the stereo when I plug in the mp3 player into the Graves USB charging port.
I pulled the cluster out last month chasing an inop cruise control thinking (hoping) it was a cluster connection that was undone. But alas, like you, I could not find any apparent loose connectors. I put it all back together, carefully, and nothing has changed (including the CC not working either).
The SI board is one of Ivo's battery-less boards and has been in nearly 10 years without issue.
I also replaced the temp/fuel gauge module with a NIB unit about 15 years ago (fuel level issue was not reading accurate); it has worked (apparently) flawless since then.
I do have to clean up the HU wiring (power & speaker) since it's a bit of a mess. This might be at least part of the issue, but not sure. While I didn't separate out the power connection from fuse 5(?) with the Aux Fuse Holder (really wished I had when I replaced the main fuse box), I do have a substantial separate ground wire from the HU to the main G101 (the one under the steering column). I am pulling the whole amp board out chasing down a loss of the right side of the system this weekend so more to come on this whole issue.

So, lot's more of these tests to implement. But I, like a lot of you, are not well-versed in electrical troubleshooting so I tend to shy away from diving into serious diagnostics which is why this has been dragging on (and on, and on...)