M3 Charging Problems

[led]

My 99 M3 is not charging correctly. When I check the voltage at the battery in the trunk, with it running, I get 12.0-12.5. When I check it under the hood I get around 14.0, I also get around 14 at the lighter. Battery holds a charge for 3-4 days with regular use then i have to put the charger to it. Why would it be so much less back at he trunk

[marti5]

Because it loses current along the cables to the engine , apart from that I would deffo say its your alternator.

[saltshaker185]

check what kind of voltage you are getting off your alternator. sounds like its not doing its job of keeping the battery charged for you.

[led]

Found it, bad connector on one of the wires that connects to the block under the where you can jump start from. Connectors appeared ok but when you moved it the voltage back at the battery went up to 13.7. thanks for the input