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Topic Review (Newest First)

  • 01-30-2011, 05:01 PM
    Craig in Canada

    Re: Pic of my meter reading

    From things that I have seen, turning the ignition to "on" can result in 20+A. This would definitely blow any fuses in your meter (if it has any).

    Take a pic of your full meter face, not cut off like the last time. It sounds like you're connecting the meter inline properly, but you should be on the 10A DC range on the meter and have the red lead plugged into the separate "DC 10A" input plug that I suspect it has. Don't turn the ignition into the full "on" position. Reconnecting the battery through the meter will wake all of the accessory stuff on. When you turn on the ignition you'll have the entire ECU, transmission computer, t-stat heaters, mirror heat, nozzle heat, MAF hot wire, aux coolant pump and a million other electrical loads on. This isn't necessary and could put your meter in danger.

    I think I saw almost 5A with just the trunk lights, body computers and the CD changer checking for discs after reconnecting the battery through my DMM. Mine dropped off to about 2.6A for 16mins and then 24mA (0.024A) when asleep.
  • 01-30-2011, 03:24 PM

    Re: Pic of my meter reading

    Regarding how I do the battery load test. I could very well be doing it wrong, I don't have any notions of being a sparky.

    This is what I think is done:

    Disconnect the negative lead of the battery

    Put the DMM online between the negative battery post and the disconnected lead. Set DMM to amps.

    Turn ignition to position 2 without starting car, and then back to off. Meter should now read 'pre sleep' amperage for about 16 minutes, followed by a drop to 'sleep' amperage levels.

    I will try this again today.

    Michael1997 540i Automatic
  • 01-30-2011, 09:15 AM
    Craig in Canada

    Re: Pic of my meter reading

    Sorry I didn't see your post below where you used the DMM to measure ~14 volts while idling. That's way better than your test 13 numbers and the alt voltage looks OK.
  • 01-30-2011, 12:13 AM

    I had the same questions. That doesn't look right.

    Knoxville, TN
    BMWCCA #407627

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    1989 E30 325i (Alpine White) Retired
  • 01-29-2011, 09:39 PM
    Craig in Canada

    Re: Pic of my meter reading

    You're reading the meter properly, but that reading is highly questionable.

    I have just completed a "sleep test" of my car as well. I can tell you that pre-sleep the computers plus the trunk lights consumed 3A (3000mA) for 16 mins until the car went to sleep. My Fluke DMM has a 300mA and 10A range with separate plugs. They are fused for those values as well. Running more current would pop the fuse and the meter would read nothing (and no power would be conducted). I had to use the 10A range to ensure that pre-sleep wouldn't pop the fuse. This meant that precision was low when the car finally went to sleep (mine said 0024 mA).

    If your meter has a mA range, it is hopefully fused. I can guarantee you that the pre-sleep current should blow that fuse. I see your meter has a 10A range in a different colour, probably a different plug too for the reason I described on my meter (fusing). I expect that's the yellow "DC 10A" in the bottom left of the pic.

    Now, please don't take this the wrong way, but how EXACTLY are you connecting this meter to do this test? You need to be disconnecting the battery, putting the meter inline, and then running the entire car through the meter. This should be giving you off the scale readings. When I reconnect my battery I get a spark from all the crap powering up - CD changer starts, interior lighting etc...

    Further, like I said in my other post, if you have 12.1VDC at idle stop playing around with the sleep test and look harder at the alternator in my opinion.
  • 01-29-2011, 07:22 PM

    Saw your meter pic and it did read as you said (m)

    However some meters have higher internal resistances at low ma settings. In which case you should take the reading with the meter set on the 10 Amp scale.
    Your 20ma reading sounds fine. My M62 idles at 500 and reads ~12.2 at night with the lights and heat on. If I turn on the seat heat it drops a bit and then recovers. Raising the idle will bring it up to the low 13's.
    I still think it's your battery or a bad battery cable connection or engine to chassis connection. Have you checked those?
    Driving around at night doesn't do a lot for charging the battery.
    14.1 volts is really enough to charge six 2.2volt lead acid cells, ~13.2 volts. 14.5 would be a bit quicker.
  • 01-29-2011, 06:06 PM

    Looks like that to me.

    Ed in San Jose. BMW CCA member since 1987 (Nr. 62319). Golden Gate Chapter. '97 540i 6 speed. Build Date 3/97. Aspensilber over Aubergine leather.
  • 01-29-2011, 04:58 PM

    Pic of my meter reading

    Am i reading this wrong?

    is this not .11mA?

    1997 540i Automatic
  • 01-29-2011, 04:56 PM

    Re: Was that .02 mA, or 20 mA? 11.4 V is a dead>>

    Well, you could be right, but I am not really sure exactly what the instrument cluster display is showing during this 'test 13', I just was watching it looking for spikes or dips while I was driving and saw none.

    This morning I went out and measured voltages after sitting overnight. The car started right up and I got a constant 13.9 - 14.1 volts across the battery at an idle. I turned on the ac and all the lights and was still getting a constant 13.9 volts. I left the meter connected and turned off the car. The volts dropped immediately to 12.4V and after 30 seconds fell to 12.22 volts and sat there. I disconnected the negative lead, and got a reading of exactly 10mA of load. After 20 minutes the load was Still the same. See next post below for a pic of my meter, maybe I am reading it wrong.

    This is all with the FSU removed since last nite.

    While the car was running, I switched the meter to AC volts and did get readings which fluctuated between .02 and .04 volts. Not sure if ANYTHING non-zero is significant, or if .04 volts is essentially zero. If this small voltage indicates a bad diode or two, then perhaps this is the problem. 1997 540i Automatic
  • 01-29-2011, 03:42 PM
    Craig in Canada

    Re: More charging system woe information (long)

    12.1 while idling is not normal AT ALL. I get 14.0V while idling. I can turn everything there is on and it will still come back up to about 14.0V while idling. 13.4 will slowly charge the battery, but is still lower than it should be. Your alt isn't completely toast, but something is going on. Stop looking at the FSU and investigate the alternator.

    Now, the M62 can idle as low as 500rpm which is lower than my M52, that can contribute. What's the voltage look like if you turn the AC on?

    Also check the easy things and make sure your belt isn't slipping or something like that.

  • 01-29-2011, 03:10 PM

    Re: More charging system woe information (long)

    Last nite I did the 'unlock' of the instrument cluster and did a nitetime drive of about 20 minutes around my part of the city displaying the voltage on the instrument display (test 13, I believe).

    When idling, at a red light, voltage was about 12.1 volts. When moving above an idle, voltage was a constant 13.4 volts. Never saw any dropouts or spiking.

    I was doing searches and found a lot of write-ups on the 'intermittent FSU failures', so I pulled the FSU out last nite and will go a couple of days to see if it has any impact on my startups.

    I had my battery out of the car and tested on Autozone's bench tester twice. Both times took about 30 minutes and tested fine. Battery is less then 2 years old Will try Jim's suggested battery test tomorrow. Drive it around today, get home and disconnect the battery overnite and test the voltage tomorrow, loaded and unloaded.

    Thanks again for all the input, I hope to finger the culprit soon.

    Michael1997 540i Automatic
  • 01-28-2011, 11:32 PM

    The voltage will vary depending on the battery's (

    need to be charged. Mine reads about the same as yours but after it charges up from what the starter used it's back down to 13.4 or so.
  • 01-28-2011, 11:27 PM

    If your alternator is outputting 13.9 -14.1 volt (

    Your alternator is OK, your battery is the problem, it is not holding the charge.
    Drive it or put it on a battery charger so you know it is fully charged. Then disconnect the battery cables and measure the voltage after the cables are disconnected and then again in 24 hours. If it is below 12 volts it's your battery that is bad.
    You could also load test it to see if it stays above 12 volts by turning on the headlights (engine off) and reading the voltage after 2 minutes, below 12 volts and it's bad.
    I think you mean 20ma, not .02ma, right.
    My car has been sitting for over 3 weeks without being started and it reads 12.4 volts, I checked it the other day when I was working on a current mod. My battery is 2.5 years old.
  • 01-28-2011, 11:17 PM

    Was that .02 mA, or 20 mA? 11.4 V is a dead>>


    The general module shuts down the car after 16 minutes.

    Measure the AC voltage when the engine is running. S/b essentiall y zero. If you get a measurable voltage, it may very well be that one or more diodes are bad.

    My alt runs at 14.5 V.
    Ed in San Jose. BMW CCA member since 1987 (Nr. 62319). Golden Gate Chapter. '97 540i 6 speed. Build Date 3/97. Aspensilber over Aubergine leather.
  • 01-28-2011, 08:59 PM

    More charging system woe information (long)

    Here again regarding my starting woes. I was going to update the original post, but for some reason it is closed to further posting. Here is my original post text:
    ================================================== =====
    "So, I have had hard starting for a few days, so I went to my local Autozone and the battery checked out okay. Checking the alternator, he said the output was fine, but his little checker said an internal diode was bad inside the alternator.

    So I am guessing the voltage regulator is bad, and that it is inside the alternator. Do i just order a new alternator and replace the whole thing at once, or can the VR just be swapped out?

    From my searches, it seems like the '97 is a simpler swapout than later years, does anyone have a web writeup on the procedure? One post said to expect about 1.5 to 2 hours for the job."
    ================================================== ======
    I got lots of suggestions about things to check. I have been 'bandaiding' the situation by taking a long drive once a week or so, which seemed to fully charge the battery and give me 4 or 5 days of pretty good starting.

    I finally got around to buying a multimeter and did some of the suggested tests. Here is what I got:

    When car is off, battery voltage after sitting overnite was 11.4 V. The 'battery test function' of the multitester said my battery was good.

    I disconnected the negative lead and got a reading of .02mA. I think this indicates no significant battery load. I reconnected the battery and started her up.

    I got a constant reading of charging between 13.9 and 14.1 DC volts. I think this is satisfactory. I shut her down, disconnected the battery again to measure load and again got .02mA. Does disconnecting the battery shut down all the loads that are supposed to be there for the 17 minutes? If so, how do you measure them?

    Anyhow, if it is indeed a bad diode, I was told that this suggests that the same circuit that charges the battery when running allows discharging when the car is off. Do I have that right, and if so, how do you measure that?

    I now have the cash to replace the alternator, but hate to pay the $225 without confirming as much as I can that it is the problem.

    Sorry for the long post, thanks again for the help.

    Michael1997 540i Automatic

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