I have a bmw 3 series and have been having trouble with the car not starting. it has had a new battery and last week a new alternator but now seems to be worse

change alternator

I am having the same problem same car & year

did you ever find a solution?

have your charging system checked to make sure alternator is charging to specs, also make sure no light are left on, (trunk light ,glove box mirror light.it sounds like you may have a draw somewhere, may be alternator or something is on, hope this is helpful.

My 2003 325xi died on the highway a few weeks ago, and I thought it was the battery. It turned out to be the alternator, which was an expensive problem to repair. If your battery is new, it could be the alternator, or a problem with the electrical system. I find the BMWs to be too complicated electrically, which often leads to problems! I'd check your alternator...

first off never never never trust a tow truck driver they are idiots, it takes a BMW 15 mins to go into a sleep mode before a draw can be mesured, as for the dealership they should have caught that using the Midtronics batt/alt tester that is standard from BMW 2.5 years for a batt replacement is reasonable especially in a BMW based on the high demand on the electrical system, I just replaced an alt on an M54 enginge just today so they do go bad, have them give you a print out from the midtronics with your VIN on the printout showing your alt is bad and what the batt is.

I have the same car I had the same problem.If you have the correct battery for your car with the same problem you have a short or positive ground in your dash/electric fuel pump/fuse box also be carefull of how you take the key from the ignition and if they're old replace them.

a common fault for flat batteries reguardless of car band is the boot light.check that the boot light is turning off when the boot lid is closed.

sounds like your alternator....

Yes, you need a new alternator, and probably a new battery too since it gave up the ghost while slowly dieing from the bad alternator!

Good luck

Sounds like an alternator problem. A bad diode can drain the battery(feed back). Replace alternator and if battery is more than 3 years old replace it too. It takes 20 amps just to power the fuel injection. The Bosch alternator should be rated at 100 amps or better. Low output will affect everything you described. Perform an OBDII scan for a look at stored faults. Let the scan be a guide to any other problems that may be present