car has no +power

[bmw325csi]

hey guys, my car has no power. The only way it turns on is if i jump it from another car. After i disconnect the jumper cables and turn off the car the battery dies. i did a manual code check and it said "dme main relay". what is that, where is it? any ideas. i tried to charge my batt, i tried a diff batt too.

[whiltebeitel]

bad alternator?

[3toedshewie]

I think what you are looking for is a relay that is shaped like a cube and has 5 prongs, located on the drivers side in a black box just in front of the big fuse box with the clear lid, on my 92 vert the relay is the one most to the front of the car and is white in color. - let me know if this helps