Hi all! I need help here!

Recently my red battery light in instrument cluster lit up several times, each time it lit up, it only stayed for several minutes and went away. I used DIS to check the fault code today, it showed 7 times of 'overvoltage' (14.6V on alternator output, 13.8v battery) and 1 time no communication with DME.

Any idea on this? What is the problem? Is the alternator dying or the battery dying? Thanks for help!

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--2004 E53 X5 4.8is - ECE version; right hand drive; Located in Hong Kong; ext. black sapphire metallic; int. leather black; adaptive dynamic bi-xenon headlights; 16:9 onboard monitor w/o navigation; 20" genuine BMW Y-spoke 214 wheels with Bridgestone Dueler H/P Sport tires; Int. rear view mirror w/ compass.