Thanks for the confirmation of hard wired ultra gauge good luck with the regulator. How dear was the regulator ?

The regulator was around $120 through BMW online. Not cheap, but this is the 220 Amp regulator as my X5 has 4 Zone climate, which I assume means I have the heated rear seats and other HVAC loads.

Hopefully this is all I need and will resolve the problem, but I still need to see if I can make up my own simple charge indicator with a few resistors and an LED mounted somewhere. This is CRAZY that there is no indication for a basic Charging 101 failure. Seems to me someone really dropped the ball on the charge indicator for a total alternator failure.

Something at Bmw online was 120. Nice to learn. I looked up alternators at 5-600 and freaked out. Just ordered the ultra gauge.

If you want a good way to find decent prices on parts, use the BMW Master Parts catalog - BMW Parts Catalog, then get the part number(s) and plug them into this tool - BMW Part Number Price Comparison for Windows & Mac

I think you will like the UltraGauge. It takes a bit getting used to and setting up, but has a lot of cool features. Also reads OBDII codes, Readiness Monitors and can clear codes in addition to monitoring most standard OBDII info along with the Voltage at the OBDII port and you can set threshold alarms. Given how hot the 4.8l runs, setting an upper temperature threshold is probably wise. I actually run a HamburgTech 90C thermostat in my 4.8l as 108-110C is WAY too hot as far as I am concerned.

Given there is a problem with at least the V8 E70 and possibly other models that may not always alert the driver that there is a problem, for the small amount you pay for the UltraGauge it is well worth it.

I purchased the windshield mount, HIGHLY suggest this, I have the gauge just on above the dash on the far left side. Almost touching the dash. Reasonably easy to reach, easy to see, hard to see from outside of the vehicle.

Just run the cable down the left side of the dash, can be easily tucked in and then wrap the excess wire on the OBDII connector end. Plug the OBDII connector in and let the Gauge do its job.

You may exaggerate another N62 problem-the carbon build-up. They get a lot of that even with the stock t-stat, lowering the temp by 20C may get you in trouble quickly. I dont know if you have smog inspection there, but having non-functional SAS is not good if you do. The good news is that I am working on a SAS emulator which will make the life easier for many folks ;)

The later N62's like mine do not have a SAS/SAP system, or at least non CA vehicles do not have it.

I am amazed how quickly my N62 goes into Closed Loop on start up, it is often before my UltraGauge actually boots up. Sometimes like in 15 seconds or something crazy fast. The UltraGauge has a Open/Closed Loop symbol on the display full time so you can see what is going on.

Not sure when the N62 quit using the SAS/SAP system, may have been with the E70 chassis?

Bit am aware of the carbon problem even as far back as the S62 engines as well.

I did not know that. You may be good then.

I am having the same issue. It left my wife stranded in the turning lane on a major road. I plan to replace the alternator this weekend. It amazes me how this car seems to know everything except basic things like volts.

And I can tell you that you might have about 25-30 minutes of run time on a good battery before everything starts shutting down.

This is really something that I think needs to be reported to NHTSA as a problem because it is a dangerous problem that can render the vehicle incapacitated WITHOUT a specific warning about a charging problem or the engine shutting down.

You WILL get plenty of warnings about subsystems shutting down, but I even doubt there will be a warning when the engine finally shuts down.

Luckily I was able to find a spot on a road that had no shoulders due to construction and I decided to pull off probably just in time before the engine shut down. And if you read my account the battery was depleted enough that the engine would not restart and luckily I had my portable jumper battery and a BIG one at that.

The nice thing about the UltraGauge is if it does not come out of sleep mode, you likely have a no charge at start up, but it will not give you a specific warning unless you unplug the UG and then plug it back in, this will force a restart of the UG and if you have threshold alarms for Voltage, they will trigger. This is the only downfall.

I may just make up a low Voltage alarm in the long run because this is not something that you can rely on for a wife or teen to watch out for.

So to add to this mystery, which may or may not ever get "resolved", here is an update.

So I was waiting about 1 hour in the car for a family member yesterday with the radio on. I did make a point to turn off the Auto Headlights so the Angel Eyes/Parking Lights would not be on. Right about the 1 hour mark, I heard a chime, looked at the dash cluster and low and behold there was a Battery symbol. The iDrive display did indicate something about a Battery Discharge problem, do not recall the exact wording.

I was a bit worried that I would not be able to start the engine, but I figured I might as well try to start the engine and attempt to replenish the battery because I would likely be waiting a bit longer. I did have my super size MicroStart with me in case I needed it. Well the engine started, with a slight struggle, but not enough to loose the clock or any other settings.

So this does tell me there is some form of battery monitoring that does work in the vehicle, but it apparently only works for battery discharge when the engine is not running?

I have a new Voltage regulator waiting to be installed, weather has been too cold to fool with it so far. Since the weather has warmed a bit I have not had as many no charge problems at start up.

I will put the battery back on a maintenance charge and run a few tests to see if the battery is loosing its ability to hold as good as a charge as a youngster. I believe the battery has been replaced in the vehicle once, but I need to check the date and battery performance for good measure.

In the meantime I will research and think about how the battery charge circuit may work and alert the drive to a charging system problem as well as think about building my own simple charge system LED to monitor what is going on.

Not sure if the BMW system would be simple to modify or spoof, probably more of a programming issue that the average Joe cannot address.

I am sure there will be more to follow.