The X is killing batteries Left and Right

[puddinboo]

sounds like alternator.

[crystalworks]

As suggested... you are going to have to monitor that alternator to narrow down your diagnosis.

[BMWX5CHI]

Originally Posted by jsoto

Ahh. This is where I'm stumped.
On the most recent, battery tender on battery. Fully charged.
Rested overnight, read 12.7 on the MM in the morning.
After breakdown, it appeared the + has some play in it. Minor, as it was tight, but not tight enough that I could not make it move.

With the said, theoretically, it should have been charging the battery ? The connection was good enough to start the car..in the morning. Before even doing the disassemble process, a amp clamp on the P was showing 45 amps declining downward when I boosted the terminals up front to start the car. BUT, with the shot battery, I can only conclude the vehicle was running off the battery the whole entire time during the 50-60 mile drive...

Take a look here. My X was draining the battery, thought it was a draw but ended up being the alt. hope this helps. GL.

http://www.xoutpost.com/bmw-sav-foru...in-solved.html

[fmugur]

Just a quick update. I just replaced the voltage regulator today and the alternator is back in business. Replacing only the brushes wasn't good enough in this instance. It seems like in some cases when the voltage regulator dies you can kill the battery with uncontrolled voltage/current.

[crystalworks]

^Glad you got it sorted. Yes, over voltage and under voltage can kill a battery for sure. Mine was swinging from 11.5v to 15.7v... no bueno.

I just put another alt. in there and called it a day. I've heard of varying success with new VR's only. Was a $240USD alt... though I see you are in the great white north so maybe a lot more up there? How much was the VR and brushes?

[fmugur]

A rebuilt alternator is $500-600 here and the VR was $100 with overnight shipping. The brushes were only $10. Last week when I did the brishes only it took me more than half a day although I have done the VR on the other X5 a couple of years back... forgot how, getting old
Today, I was done in half an hour including the VR swap. I also did the 330xi last week but much easier job and brushes only fixed the problem.

[crystalworks]

^Wow. Huge difference in price. Well, glad you got it all figured out. A randomly dying X can be a massive headache.

[jsoto]

Was you ALT light ever NOT on.
For the past 3 months, I have NEVER seen the bat. light on the cluster ever come up

[BMWX5CHI]

Originally Posted by jsoto

Was you ALT light ever NOT on.
For the past 3 months, I have NEVER seen the bat. light on the cluster ever come up

The light on my X would flicker a bit but wouldn't stay lit and would go away. Try this, apply your parking brake, put her in drive and turn on all accessories, wipers, lights, heater, ect. Then with a multimeter, check voltage. If it's any under 13v, I would think its your alt if i'm not mistaken. That's how I found out it was my alt.

[jsoto]

I had to step away from the problem child for a couple days but I'm back on the brainstorming.

Not doing any long driving , if not short driving until I have a clear plan....
Having it twice die out was not fun. I might have even have put her upforsale and the problem child stalled out on my on the freeway. Luckily it was local streets 2X.

I did monitor both V and A briefly while driving the car. Not via cluster unlock. I had my amp probe/mm connected while driving and did not see any anomolies.

Just thinking outloud but maybe when the Alt get's hot, then it starts acting up ?
I've been doing testing from cold/coldish starts......not really planning to drive.
Paid about $80 just in tolls on the last event, and another $20 tip to the driver.