Dead Battery Again.

[Lotsaputts]

I'm guessing the drain is more than 500ma as the needle passes 500 to it's mechanical stop. I hope to resume diagnostics today with no rain.
Dave

[DaveW3009]

Ok, this is going to be my last post on the subject. I am a retired Electrical Engineer and retired from a second career as a Physics, and Elelctrical/Electronic circuit design teacher. It is ALWAYS easier, safer and more accurate to measure voltage and calculate current rather than measure current directly. If you are pinning your meter at 500mA you are in danger of damaging the meter and blowing its fuse. Going systematically through the fuses measuring Voltage at the test points is easier and safer than istalling an ammeter in series with the main battery cable and unplugging fuses. Plus that wiil not find a parasitic draw in the cable from battery to fuse box.

Dave

[Lotsaputts]

Thanks Dave. I do not let the ma meter stay connected. I use the probes in each hand and and release them instantly. So far so good. If none of the fuses exhibit the high reading I'll have to start wiggling the wires I can get at and have a friend at the battery to check each wiggle. My car storage 10/22-23 so if I find nothing I'll continue to disconnect the negative post while parked and pick it up in the spring. During that time I'll have the battery home and on a 2v tender.
Dave

[Lotsaputts]

So the plot thickens. I set up my jumpers so I could measure the drain current from the front and found 2 circuits. The major drain was #9 which feeds the radio, pegging the 500ma scale; reduced to 200 ma. Still not happy so I kept going and found #31 which dropped the current to 30ma after removing. Trouble is it feeds antitheft, clock, immoblizer, exhaust diagnosis and worst of all the instrument cluster. I can do without all of them except for the instrumentation. So more work needs to be done but not till next year. Any ideas would be appreciated. I'll just leave #31 out except when I go for a putt. Thank you for all the comments and suggestions; they were all helpful.
Dave

[Hoyt Clagwell]

Boy was my guess wrong. embarrassed.jpg Electrical troubleshooting is not my strong suit (sleeping is) but here's my take anyway. Most of that stuff, including the cluster, should not be powered when the ignition is turned off so could it be the ignition switch itself?

[bdiefAZ]

Do you have an alarm siren?

[Lotsaputts]

Do you have an alarm siren?

I don't know, Brian. That is not on the fuse list under the box cover so I'm guessing not. Hoyt's last comment is noteworthy. How can I test the ignition switch without pulling it?
Dave

[crashgordan]

following.

[khammack]

If you do need to pull the ignition switch here is a link walking you through the process. It also mentions electrical gremlins can be caused by the switch.

https://www.pelicanparts.com/BMW/tec...eplacement.htm

[DaveW3009]

A lot of circuits are powered when the ignitioin is off. Radio, entry system, immobilize etc. IiRC the constant ighnition off draw on an E46 is specd at around 50mA. Any number of failures or degradation of electronic components in these systems can increase the current substantially. Remember we are dealing with 20 - 25 year old components. When my instrument cluster went completely dark in my E46, I found out how much functional information passes thropugh the data busses in the cluster. Parts of the cluster are definetly powered when the ignition is off.

Dave

[Lotsaputts]

Dave, leaning on your background and experience, do you think fuses 9 and 31 showing excessive draw would be ignition switch related? I looked at Khammack's link to Pelican and the procedure to
change it is pretty daunting. I'd like to ensure the switch is the issue before changing it, but that won't happen until spring 2023. Guess I've got a lot of time to contemplate. Thanks to you both. Taking a leaf peepin' putt today. Peak color has arrived in this county. One of our spectacular wonders in paradise. Midnight tonite I turn into an 82-y.o. pumpkin.
Dave

[DaveW3009]

I would think it unlikely the ignition switch would cause leakage current in only two circuits. My suspicion, is that the 300 mA or so in the radio circuit is excessive and something in the rado has failed causing it. Radios have two 12 v power inputs, one powered off with the ignition,the other powered all the time keeping your station presets stored in memory. I bought a 2006 Outback that was only 6 years old and the PO had had to disconnect the always on input as it somwhow went excessive and drainws the battery in 2 weeks of un-use. Still have the car and the battery's been fine, expcept you have to retune the radio every day!

I would pull that fuse and see if that fixes the problem. That circuit might power something else that is need, so you might track down that powewr lead to the radio and try disconnecting it.

I'm in NE MA been trying to get a day to meander up to VT for foliage. Byabysitting grand kids has been getting in the way!

Dave

[sleeperz]

A couple of thoughts:

1) Lead acid batteries must have a maintenance charge on them whether used or not. See this article for an explanation of why. https://www.batterystuff.com/kb/arti...d-battery.html

2) Not all new batteries are perfect. It is possible you bought a battery with a bad cell in it. I used to test those with a hydrometer. There are other ways to do that now. https://www.youtube.com/watch?v=WzRs0L8Wi4g

I have also seen a bad voltage regulator on the alternator draw a battery down. This is actually a common problem on many cars I have serviced. If the battery tests ok, might check that. The Diodes can become defective and cause some leakage that draws down the battery.
HTH

[z3forlife]

Fuse 9 also powers the amp/s in the trunk. You can pull the head unit and disconnect the harness and remove the trunk liner and unplug the amp or amps if a late model that has the 2 amp system. The alarm module is behind the glove box for fuse 31

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