325i flat battery/battery light on dash on when ignition off

[flashpat]

Hi the battery in my 325i keeps going flat,I have replaced the battery but it hasent solved the problem.
The battery runs down to about 11.3 volts which wont start the car and when i jump start it and its running it measures 13.4 volts.
Also when i turn the car off and take the key out the red battery light on the dash stays on......?????
Any ideas???
Thanks folks

[manse73]

Alternater is giving up

[Brianmoooore]

Alternater is giving up

Alternator has given up. Diode has failed, allowing 12 volts + from the battery to reach the alternator side of the battery light, with the other side of the light being effectively earthed by various ignition switched circuits.

[daimlerman]

Alternater is giving up

Alternator has given up. Diode has failed, allowing 12 volts + from the battery to reach the alternator side of the battery light, with the other side of the light being effectively earthed by various ignition switched circuits.

Correct technical term;

The alternator is buggered.

[flashpat]

Thank you very much gents.
It well be a week or two until i get home to get it out and reconditioned .

im i better getting refirbed or buy a new one??????

[chippy1947]

hi i would go for a refurbished one from a reputable company they mostly do exchange unit

[Brianmoooore]

Second hand one will be fine - diode failure is unusual.
Just remove the regulator pack and check that the carbon brushes aren't so worn as to be on their last legs, and renew the pack if they are.