battery/ power issue

[rede30]

I am helping out a friend, car is not in my possession. My friend left the lights on for four days in his 325ix. Battery drained, got a new one but after he plugged in the new battery the lights are still dim and car wont start. It will start with a jump and run great but doesn't have power to run lights or start the car after it stops.

My first instinct is to say the new battery is bad. If I was to rule this out do you guys have any thoughts on what could cause this? It is not really a charging issue since when the new battery was installed it did this

Can there be a major current draw when the car is on that makes nothing power up fully? What about the fusible link?

[jlevie]

Check the battery connections and make sure they are clean and tight. Also check to see if the new battery is fully charged (it might not be). A fully charged battery will show 12.7v.

The alternator may not be working properly. With a fully charged battery you should see ~13.5v at idle and ~14v at 2500rpm. Adding headlights and HVAC blower load, the system voltage should still be above 13.5v at 2500rpm.

[EuroSportChicago]

^ sums it up.

Once the car is started does it run as normal or is it still dim?

Take a multi-meter and check how many volts at the battery terminals while it is running.