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  #1  
Old 02-10-2016, 04:42 PM
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Interesting Charging System Issue

So I have an idea that my 2008 4.8l X5 with about 82k miles may need a new Voltage regulator, but I thought I would toss out my symptoms to see if anyone else had a similar situation and also check to see if anyone has ever had a charging light come on when there was a charging problem on their E70.

Background.

1. I have been running an UltraGauge on my X5 to monitor Engine Coolant Temperature and Charging Voltage for about a year. One thing I like about the UltraGauge is it has an automatic "Sleep" mode that will wake when it sees an increase in the Voltage once the vehicle is started.

2. I started to notice some sporadic high Voltage threshold alarms from the UltraGauge that I had set at approximately 15.2 Volts, so I knew there may be a Voltage regulator problem this past Fall.

3. I then noticed from time to time my UltraGauge would not come out of "Sleep" mode on start up intermittently. I could then easily reach under the dash, unplug the OBDII connection for the UltraGauge, then plug it back in to "force" the UltraGauge to start. Then this is where the fun started. I would have a no charge situation.

4. I have been "managing" the no charge situation by watching the UltraGauge on start up and if the UltraGauge would not come out of "Sleep" mode, then I knew I had a charging problem. I typically could just shut down the engine and restart it and this would resolve the no charge situation. Given it is of course the middle of Winter, I have no interest in trying to remove the alternator in the sub-freezing temps and 2+ feet of snow we have recently been dealt.

So what has been puzzling throughout the 2 dozen or so no charge events over the past few months, not ONCE has there ever been any sort of charging system warning, error light or indicator to let me know there was a problem. If it was not for my UltraGauge, I would have been stranded somewhere due to a no charge situation.

I have a number or Pro level scan tools, plenty of meters, automotive scope meters, Amp probes, load testers, battery testers and even Carly for BMW an INPA. I am banking on the Voltage regulator being flaky so I have ordered a replacement, but again the puzzling thing is NO WARNING what so ever.

So I thought I would toss my case out to see if anyone has run into similar problems with a no charge situation with NO WARNING. Might be there is a design deficiency in these models where the are no indicators for a now charge situation. Maybe there is a bad connection or a bad ground that is causing no charge problems without any warnings. I am just blown away that there is NO WARNING when there is a no charge situation on my vehicle.

Maybe the problem will be the Voltage regulator and maybe when I replace it my problem will be resolved and there WILL BE a warning in the future if there is a no charge situation.

I have been just too busy, weather has been to crappy and I have not been highly motivated to resolve the problem yet because I have been able to "manage" the situation, but the no charge situation seems to be getting a bit more frequent and I may be outside freezing my hands trying to R&R the alternator in the next few weeks.

Does a no charge condition trigger any sort of warning on the early E70 models?

Or am I just the lucky one in this situation?

Thoughts, comments, similar experiences??
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Old 02-10-2016, 11:47 PM
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Sorry, another flaw of N62. Countless cars with no charging/intermittent charging condition and overcharging (up to 18V I have seen) with no warning whatsoever.
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Old 02-11-2016, 10:56 AM
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Thanks for the reply, I was wondering if this was a "feature" of the X5 or the newer CCC iDrive vehicles. Seems to me to be a BLATANT oversight.

So after I posted this, I needed to pick my wife up at the airport, arrived early and hung out with the radio going for about 20 minutes. She called and I started the car while speaking with her on the phone. I forgot to look at my UltraGauge!

So I roll up, pick up my wife and head out of the airport on a restricted access road that has a BUNCH of construction and most of the shoulders are taken away by Jersey Barriers.

Cruising along an I feel a jerk, then the iDrive pops up a message about the All Wheel Drive is in fault. I am thinking, great, one more thing to screw with. Still not putting 2 & 2 together yet because I am having my wife read exactly what is displayed on the iDrive screen. Drive a few more miles and then I happen to glance over to a dark UltraGauge. Crap, I know what is going on now.

So while I am thinking about where I can pull off with no shoulders or how far I need to drive to get off the limited access road, then things really start to happen. ABS warning pops up, then shortly there after Stability Control warning, followed by Active Suspension and the Airbag!! I hit the lottery.

So I am quickly realizing the battery is quickly avalanching and running out of power. I have got to pull off otherwise the engine may shut down and then I will be really screwed. Then all of the sudden I see a partial shoulder where construction vehicles can access their portion of the road, I decide to pull off. Not the best location, but as least I am not stuck in the middle of a travel lane.

Let the car idle for a moment, then decide to shut the engine off because this is really the only way to get the charging system working, or at least how I have been managing the situation when it comes up. Hit the start button, NOTHING. The the drama starts. Wife is none to pleased. "Why did you shut the engine off ..........." ! Oh well, can I do anything right?

So I just happen to carry one of the large MicroStart batteries in the vehicle that is about the size of a VHS tape. Grab that, pop the hood, hook up the MicroStart, attempt to start, something, but not enough. Give the MicroStart a few minutes on the battery, hit the start button and I am in business. So I wait a few moments, anxiously watching my UltraGauge and it boots up. This is GOOD. Once the UltraGauge is working, I see 14.8 Volts.

Scramble out and grab the MircroStart and close the hood, I am back in business. Having the MicroStart in the car = PRICELESS!!

So I can now see I need to design a simple LED charge indicator for my X5 since BMW has no idea how to notify the driver that there is a charging problem other than modules and subsystems that are shutting down or going into some error mode! Starting to wonder if this is an engine specific problem, a vehicle platform problem, out of day software for the DME or other modules in the car or what is going on.

Totally unacceptable. Granted I was aware of the problem and had another means to monitor it, but having a basic indicator for charging problems has been around for almost 100 years. I guess BMW figures BMW Assist is just supposed to automatically dial out and have a BMW Assist Operator tell you your car has a problem, assuming you subscribe to BMW Assist??

I will update the thread with what I find on the charging problem and if I come up with a simple charging indicator.
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Old 02-11-2016, 11:38 AM
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I had the exact same problem on my 08 4.8i right at 80k. I opted to have my alternator rebuilt. It was actually working when I took it in but several of the diodes had cracked ceramic insulators so considering the mileage I had them rebuild the whole thing, roughly $250 and I'm back in business for hopefully another 80k.
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Old 02-11-2016, 11:57 AM
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Here is how the system is supposed to work: voltage regulator is commanded by the DME over LIN bus-a few simple devices are connected, including the IBS. DME is supposed to evaluate the information from IBS and send commands to the voltage regulator. In case of something wrong the DME must send a message to the CCC/CIC to display a low voltage, but somehow this doesnt happen on N62 equipped cars.
I know this exact same problem occurs on a specific Mercedes 4 cylinder engines. No charging and no warning.
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Old 02-11-2016, 11:58 AM
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I am seeing an LED and resistor somewhere in my future!

Kind of funny/sad that the DME has a PID for the Charging Voltage but nothing is done with this PID!

The SES/CEL/MIL is better than NOTHING.
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Old 02-12-2016, 12:28 AM
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Although my only symptoms so far are:
-clock resets to zero and radio presets get erased every couple weeks
-sitting in the car with instruments active for a while and battery warning comes on.
I suspect if we did bigger trips with our 2007 4.8i we would have something like this happen.

At times when running the engine I have Measured the terminals of the battery at 14.8

How could the clock reset but we can still have enough juice to start the car. Perhaps an ultra-gauge is needed for the extra feedback on voltage per short trip in the car.
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Old 02-12-2016, 02:31 AM
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Sounds like either your battery is low due to charging issues or the battery may be bad.

I have lost the clock a few times usually due to the battery getting low and the cranking Voltage dropping too low upon starting. I have yet to lose radio stations.

I do occasionally put my battery on a "maintenance" charge due to how I sometimes use the vehicle. Too many start and stops in short distances along with occasional waiting for family members with the radio on.

I do not think I have ever seen a battery warning on my 2008 4.8l yet.

You may be suffering from an intermittent no charge situation that is draining the battery and leaving it chronically low, but may make enough short trips that charging starts on a later restart.
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Last edited by jfoj; 02-12-2016 at 07:43 AM.
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Old 02-14-2016, 10:10 PM
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Thinking of getting and ultra gauge to be able to diagnose and manage the situation, it sounds like the traditional wired unit gave you more feedback than a Bluetooth one would.
Also I could put a charger in the engine compartment, just to make it really easy to get a top notch charge on the battery, power outlet is right in front of its parking space.
Obviously willing to put a fix in place too if either voltage regulator or alternator diodes are the know fix. since we don't drive it much or on long trips I have time to get the right fix planned out.
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Old 02-14-2016, 10:21 PM
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I have plenty of Bluetooth devices and multiple Apps, but the beauty of the UltraGauge is it is hardwired, application specific and automatically sleeps and starts. If the UltraGauge does not start, then there is a charging problem. I can set either high or low threshold alarms for Voltage, Temperature, Fuel Level or for any other parameter the UltraGauge monitors.

I put a charger on the car maybe every 6 weeks depending on how I am using it. I am still floored that a no charge event in my case has NO indication. You will only know once the sub modules start to fault out, in my case it the as the All Wheel Drive system when into error.

Something like a bigger Battery Tender is not a bad thing to consider, not too large and they have quick connectors. The small wall wart Battery Tenders are incapable of doing a good job on larger batteries that are heavily discharged, so I would go with something larger like this unit - Battery Tender® 3Amp Power Plus!
Note it is has limited availability, Costco and Battery Tender Web Site.


I will hopefully have my Voltage regulator tomorrow or Tues, but with temps in the 20F range, not highly motivated to replace it until I have a some nicer weather.
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Last edited by jfoj; 02-15-2016 at 07:34 AM.
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