Help! Broken down in Idaho. I've got battery charging issues (e30 m3)

[synergy141]

Hey guys, I'm on my way back from Mfest and my car has broke down. The symptoms are the same as a failing alternator but I just got the alternator tested and its working fine. I tested the battery with a multimeter while running and it shows 9volts so it's definitely not getting a charge so it's something inbetween the Battery and alt. any ideas?

[MNE30]

Grounds? That's the only electrical gremlin I can think of.

I know on the M20 there is a big ground strap from the oil pan to the frame and one on the passenger side strut tower, first things I would check.

[BenM]

Belt tension or was the alternator tested in the car?

[oliver.r]

make sure the 2 blue wires are attached to the alternator and the ground wire isn't cracked.
double chek the fusable link in the positive line and check that its intact

[10Toes]

What is the voltage coming off the alternator when it is in the car and running?

[NeoMishMoo]

Are you around any stores and how much farther do you have to drive? You could always be ghetto like me and hook up a second battery via jumper cables and that should give you enough juice to get to where you're going. I had to do this when my alternator failed once, but I used a spare battery.

Turn off your stereo and all lights to get the most power out of your battery(s).

[Farbin Kaiber]

Where are you at?

[ReallyDirtyThirty]

Not sure what set-up the M3 uses, but a voltage regulator might be causing it. My alternator was charging like a champ until the voltage regulator took a crap. It happenned really quickly for me when this part failed.

[pandaboo911]

I vote bad battery..

if you're getting 13.8v or whatever at the alternator and 9v at the battery

[iansane]

What is the voltage coming off the alternator when it is in the car and running?

.

[fronton]

two quick and easy things to check:
A. your c101 plug next to the fuse box is tightly secured to between male and female. Mine was losely twisted apart and causing intermittent starting issues.
B. your main positive cable that runs from the battery along the passenger fender: make sure none of the copper is exposed to trunk metal. This can cause a short and not allow the starter enough power and drain your battery.

[Gregs///M]

First, 9V from a car battery is dead low. I would go ahead and say you have a dead battery, needing replacement. If the battery is near or greater than 5 years old, it dead.

[synergy141]

Found the issue, the metal cooling line that runs along the left side of the block came loose. The metal bracket snapped. This is the main alt ground commection.so I just re routed the alt ground wire to another bolt on the block temporarily .

[MNE30]

Found the issue, the metal cooling line that runs along the left side of the block came loose. The metal bracket snapped. This is the main alt ground commection.so I just re routed the alt ground wire to another bolt on the block temporarily .

Called it. Glad you found it!

[aPapester]

Welcome to idaho(: