Alternator or Battery?

When I drive the car during the day I have no problems with power loss or any messages in the Idrive. When I drive at night, the interior lights flicker, the dynamic drive malfunction message comes up, the cigarette lighter does not work, the heated seats and steering wheel turn off and the idol is erratic. Also, when I am on the highway, you notice a sputter in the accelleration.

She's a 2005 with 116,500 miles. The battery is 2 1/2 years old. I am almost positive it is the original alternator.

Any ideas what this might be? If alternator, how much should I expect to pay at an Indy shop?

Thanks for the help

I'd go with the alternator. Many of the older owners (including me in my '04 645) had their alternator replaced with far less miles than you're currently at.

+1 alternator, at night time the load increases dramatically, also could be the regulator which if memory serves correct can be replaced separately !!!

I just had the same problem. My 04 645 has 50,200 miles. I had to replace the alternator and battery. The cost at the indy shop was $1200.00. All the other issues disappeared but I am getting a surge around 40 mph. It just came out of the shop on Friday.

The alternator alone was around $900. It was overcharging and ruined the battery which was over 4 years old.

I was quoted $290 for a 180 amp alternator. Autorepair estimator says its a 1.9 hour job @ $100 an hour the total job should come in around $500.

Am I missing something here? $1200??

Have the battery & alternator test at any auto parts house for free, then see what the test show. There is no sense in spending wasted money!

Good Luck!

Herb meant to say have battery and alternator TESTED for free.

It sounds like the alternator to me since the car cannot keep up with the heavy current draw when the headlights are on.

But you should have the alternator tested first, it could be a bad battery connection, the IVM module or a grounding issue.

If you have a multimeter you can test it yourself (or you can get one for $40 at Home Depot). Test the battery (car off) should be above 12 volts. Then test with car on (now you are testing the alternator) should be 13.5 or more. This is not as good as an actual load tester, but it is a good way to start if you have the tool.

Originally Posted by Yorgi

Herb meant to say have battery and alternator TESTED for free.

It sounds like the alternator to me since the car cannot keep up with the heavy current draw when the headlights are on.

But you should have the alternator tested first, it could be a bad battery connection, the IVM module or a grounding issue.

My 1st mistake in 2012!

I need to proof read my post better!