Issue with charging system

[kyrix1st]

Mine turned out to be a dead alternator. Car electric system shut off on highway today. Use caution! Had to tow it home.

[kimiraikkonen]

Originally Posted by pbonsalb

Car should not die once running if alternator is good since it will provide power to run everything even if battery is no good.

Check your grounds. There are 2 under the motor on the sides. Bad grounds can screw up all sorts of things.

Hi. Do you have more info on the specific location of the 2? I have only heard of the one ground strap on the passenger side bottom (under the felt center piece and near the driveshaft.

Where is the 2nd one? Thanks in advance.

[BGBF18]

As pointed out by a few folks, OP is experiencing a weak alternator.

I struggled with this for about six months before replacing the alternator (Valeo, non-OEM - $400) and putting in a new battery (OEM - $400).

BMWs are weird in that they run off the battery, not the alternator. The alternator only charges the battery when it gets below a certain voltage or during a high draw. It saves fuel as the alternator "decouples" via a clutch so as to reduce parasitic drag.

Alternators fail gracefully and eventually cannot place a net positive charge on the battery, which is why this issue is so insidious and painful to diagnose.

A new battery, alternator and trickle charger will keep your electrical systems tip-top for years.

Blame Efficient Dynamics - look it up.

[ItsGary]

Originally Posted by BGBF18

As pointed out by a few folks, OP is experiencing a weak alternator.

I struggled with this for about six months before replacing the alternator (Valeo, non-OEM - $400) and putting in a new battery (OEM - $400).

BMWs are weird in that they run off the battery, not the alternator. The alternator only charges the battery when it gets below a certain voltage or during a high draw. It saves fuel as the alternator "decouples" via a clutch so as to reduce parasitic drag.

Alternators fail gracefully and eventually cannot place a net positive charge on the battery, which is why this issue is so insidious and painful to diagnose.

A new battery, alternator and trickle charger will keep your electrical systems tip-top for years.

Blame Efficient Dynamics - look it up.

Don't you have Efficient Dynamics if you have Start/Stop feature to save gas?

[BGBF18]

Originally Posted by ItsGary

Don't you have Efficient Dynamics if you have Start/Stop feature to save gas?

Yes, however all E9X M3s have Eff. Dyn. - with or without the S/S feature.

Eff. Dyn. is not exclusive to M cars and rather crosses into many series.

[Scrippy]

This is like the 4th post including my own in the last month for "battery discharge" and or failing alternators. My alternator failed 3 days ago as well. $1885.57 at my local dealership. Almost makes me wonder if BMW can disseminate values to our ecu's via an active connected drive smartphone plugged into the usb or snap in adapter with connected drive running? I know it sounds mega paranoid but this is a lot of RECENT posts regarding this lately.

[Helmsman]

$1885...!?! One get a reasonable used car for that kind of money ffs!

[Scrippy]

Originally Posted by Helmsman

$1885...!?! One get a reasonable used car for that kind of money ffs!

I would not want a car for 1,800 post age 25 lol. I had the dealer do it for the warranty only. It was a painful cost though especially when an alternator is only around $500.

[ajagostini]

Like some of you, I ended up at Lone Star Bavarian Service Shop (Fort Worth), and sunk $1,600 on a new alternator and battery. So far so good! I don’t know if it’s spychological or not, but the car feels stronge than before. Thank you guys for all the good input on this subject.

[ItsGary]

Originally Posted by ajagostini

Like some of you, I ended up at Lone Star Bavarian Service Shop (Fort Worth), and sunk $1,600 on a new alternator and battery. So far so good! I don’t know if it’s spychological or not, but the car feels stronge than before. Thank you guys for all the good input on this subject.

jesus thats a lot for those two things.

[ajagostini]

Originally Posted by Scrippy

This is like the 4th post including my own in the last month for "battery discharge" and or failing alternators. My alternator failed 3 days ago as well. $1885.57 at my local dealership. Almost makes me wonder if BMW can disseminate values to our ecu's via an active connected drive smartphone plugged into the usb or snap in adapter with connected drive running? I know it sounds mega paranoid but this is a lot of RECENT posts regarding this lately.

To follow up on your paranoia...i just got in my car and to my amazement, i was greeted by dsc fault, edc fault, increased emissions, and something about engine producing limited power. WTF?! I just replaced the battery in December...so i’m hoping is that again! I don’t think i could piss another couple of thousand dollars...any ideas?!

[Solo_M_Tech]

Originally Posted by ajagostini

To follow up on your paranoia...i just got in my car and to my amazement, i was greeted by dsc fault, edc fault, increased emissions, and something about engine producing limited power. WTF?! I just replaced the battery in December...so i'm hoping is that again! I don't think i could piss another couple of thousand dollars...any ideas?!

throttle actuator failure for sure. it failed one of its predrive checks.

[Scrippy]

Originally Posted by ajagostini

To follow up on your paranoia...i just got in my car and to my amazement, i was greeted by dsc fault, edc fault, increased emissions, and something about engine producing limited power. WTF?! I just replaced the battery in December...so i'm hoping is that again! I don't think i could piss another couple of thousand dollars...any ideas?!

I had my battery coded in on the first incident. The 2nd incident and they told me the alternator was bad. Both incidents threw about 6 errors on the idrive. All would go away after leaving the car off for a few minutes and then trying again. I just had the dealer do it since I didn't really have the time myself. I just know me and I'd prolly end up doing all my pulleys, water pump a coolant flush out of pure neurotic tendency.