Red battery light on.Help!
 

well, good thing i was close to home when I noticed the red battery light on...

turned around to hook it up to DIS and it gave me a bunch of odd errors like

-relay, heated rear window-faulty
-steering wheel column radial - transmission fault
-electronic braking-force distribution fault
-brake light, right, faulty

the car doesnt start anymore...

I know a low battery throws a bunch of electrical errors but the battery is one year old.

I'm thinking alternator? How can i be sure?
I read that an instantaneous red battery light is often an indicative of a broken accessory belt.

Haven't checked that yet...but i suppose you lose power steering, alternator ofcourse and water pump that leads to overheating...well i had power steering, didnt drive enough to overheat, etc

Ordering an alternator will take a while, ill be stuck in the house this weekend...not fun at all.

How hard is it to replace the alternator on a 4.8?I've only done it on my E39 530i and that was pretty simple.

If it turns out to be the alternator, other than replacing belts, what else can I do "while in there"?

thanks guys i really do appreciate all the help i can get.

Well I can't speak for the 4.8is but when my X threw the battery light it ended up being the alt. Checked the voltage with a muti-meter with the car running and everything seemed to be ok but only when in drive and running some accessories didn't the voltage drop to 11v. So must likely it's going to be the alt. All of those error codes are most likely caused by insufficient voltage.

if your battery is dead after a year then its probably the alternator. if you remove it bring it to most auto part stores and they can test it's output.

Be aware the auto parts store only does a "cold check".

I've had 2 alternators that checked ok cold, and would regulator fail when heated to under hood summer operating temps. Not the E53 alternator.

True. Charge your battery to keep form killing it. some don't come back to well if they sit too low for too long.

Ordering an alternator takes a while?! You can walk to the auto parts store on the corner and get one off the shelf. If the shelf is empty, they can have one the next day if you discover the shelf is empty early enough.

And,the battery light does not point to the battery because the light is really a Charging System Light. A picture of a battery is easier to understand than a picture of an alternator, which is the typical problem when the light comes on.

Guys, thanks a lot so far.Id like to avoid auto parts store for the very reason of inconsistency in their product quality.Bought a reman.unit for my E39, installed it, only to find out the pulley makes an awful sound...take it off, bring it back, get another, you can understand the frustration...
Rather go OE this time...

Could be the regulator. That was my fix. You can also take yours to be rebuilt. The job is fairly easy. Removal is also easy. Take out fan. Intake. Disconnect battery. Make sure you disconnect battery. Remove 3 bolts. Maybe remove pulley. I forget. But very straight forward job.

Hey Slick thx but if it is the regulator,might as well get a new alternator right?how much does it cost to rebuild them?
Does 550$ sound steep for the genuine BMW alternator from ECS?