Please help me trouble shoot my Dash Battery lights

[j_lopez]

Folks, please help I need your expert advice to zero-in on my diagnosis. Please bare with me as I narrate my experience I believe it will help explain my problem and prognosis.

Day one- I was working on the X5 in repainting the leather, (BTW if any of you wanted to do your leather I highly recommend the leathertechworld.com) for a time all the interior and the rear lights at the rear lift gate are on. Also, the CD player (Rear) is also on, everything is dandy and good so, that evening I took the car for a car wash. After the wash on my way home, the battery lights (Dash) started to flash intermittently; Thinking I may just have wetted something, I ignored it, luckily that night it went away; So I thought since it fixed itself let it be. I have an onboard battery tender which charges the car (I use this when I am not using the car to trickle-charge the battery)

Day two- Started to work on repainting the leather again, but since it was such a nice day, we decided to take the X5 for a spin, on the road not too far from home the battery lights started flashing again. And again I ignored it thinking and feeling that all is okay. I started to loose power, the battery was flashing constantly this time, then the check engine, then the gear box, then the ABS. then the X5 died on the road.
I cranked the engine and all I can hear is the weak attempt of the starter to turn the engine over. => waited 5 minutes then cranked it again, it ran then I was able to drive it maybe a couple of hundred meters (Now going back home Anxiously!) then it died again, I boosted the car (I have a NOCO GB 30) it was able to run a couple of meters then it died again. Having watched a video on youtube were the NOCO was used as a substitute for the battery I tried that ( boosted the car and left my NOCO attached it and it worked for about a couple of hundred meters. Now that my booster is dead and my car won't start (Strater is cranking) I decided to walk home, get the other car and bought a new battery (Canadian Tire)
Having the new battery installed it lived again, was able to go home but on the way, the battery light intermittently flashes, on for a short while then off for a long pause. Thinking that the battery will charge by the time I get home I ignored it (Yeah I have that bad habit of ignoring things!)

Day 3- after being plugged overnight to the battery charger (the onboard that I have) I took the X5 to work in the morning, no lights (battery) all seems to be okay, but I can feel that I am a few horses low, and my engine is a bit noisy (probably because the X is not shifting properly) So I decided f*king shit this X5, let's go stretch your legs' so I ran the thing on the highway at above 100 km/h and alas the battery light came on again. In the afternoon after work, I drove it and there were no problems; I was able to get home but just like in the in the morning a few horses were missing in action.
So I said to myself let us Occam's razor this shoit and start diagnosis with the battery. I cleaned the terminals and then clamps then started the car, => took it for a test drive and for the first 5 minutes all the horses came back to action. Thinking that I have solved the problem, I wanted to test my hypothesis so I turned all of the accessories I can get my hands on, and...????? you guessed it -(lets say it together 1, 2 ,3 its the battery f*cking light and what else as an extra bonus, whilst turning my way towards home the X died in the middle of the road (Had I have a source of fire at that moment I swear I will burn the X to the ground (Just kidding I still love the car))

Okay Problem solving time
-Started by downloading all the trouble codes from the car- Totally useless because it's like all the codes imaginable is there- Waste of time
-Tested the voltage from the battery-
-Car off- Voltage reading is 12.98 - reading was taken after it was plugged to the onboard trickle charger
-Car ON- Voltage reading is 12.08, 12.14, 12.3, at 3 consecutive readings RPM is at 2,000

Okay since battery is new ( 3 days old) and seems to hold a good charge (Remember that car does not have problems starting when the battery has been rested or charged) I need to look at two things,

The Alternator or the belts which may not be spinning my alternator fast enough.

Examination of the belts (Which are also only 1 year old both serpentine and air conditioner) came out okay and tension is okay leads me to the alternator. By the way, I failed to mention that a strong burnt rubber smell has started to smell the same time this debacle started so I was expecting it was the belt but it was not.

Okay, what I need to know is that is the alternator definitively that is dead. before shelling 330 CAD at parts source.

My X5 is 207K kilometers and the original alternator is the one in question

All inputs are welcome. Thanks

[Joshdub]

I'd put my money on the charging system.

[80stech]

Yes, alternator would be a good guess.

[wpoll]

If you have only 12.x volts on the battery when the engine is running at 2,000rpm, something in the charging system is dead. Alternator brushes or regulator probably.

You should see around 13.5-14.5 volts with the engine at 2,000 rpm.

[StephenVA]

Chart of Voltage for battery at REST (engine off)

[LeiZ]

Your alternator is shot! Chances are the alternator bearing seized, and you don't get alternator roaring the whole time. Time to rebuild/replace that alternator.

GL


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[StephenVA]

Here is everything you need to know to test our vehicles starting and charging systems:

DIY how to test a BMW E39 battery & alternator (discussion) - Bimmerfest - BMW Forums